ISSN 2321 3361 © 2021 IJESC

Research Article Volume 11 Issue No. 03

Experimental Investigation of Arc In Dissimilar Materials AISI 304 and Monel Alloy 400 Using Swarm Algorithm Mr.R.Prakash1, Agilan S 2, Barath A S 3, Deepak N 4 and Dhinesh Babu D5 Assistant Professor1, Students 2, 3, 4, 5 Kongunadu College of Engineering and Technology (Autonomous), Tamil Nadu, India1, 2, 3, 4, 5

Abstract: The nature of welding in the aeronautical industry is characterized by low unit production, high unit cost, extreme reliability and severe service conditions. These characteristics point towards more expensive and more concentrated heat sources such as plasma arc, laser beam and electron beam welding as the processes of choice for welding of critical components. Among various precision welding processes, Plasma has gained importance in small and medium scale industries manufacturing bellows , diaphragms etc because of less expensive and easy to operate. This project the works on Plasma Arc welding and associated phenomena such as welding voltage (WV), welding Current (WC), welding Time(WT) and nozzle to plate distance(NTPD) on important parameters in dissimilar materials AISI 304 And monel alloy 400 joints. The project focuses on weld quality characteristics like welded micro structure, hardness and impact of dissimilar welded joints

Keywords: Plasma Arc welding, welding voltage (WV), welding Current (WC), welding Time(WT) and nozzle to plate distance(NTPD), dissimilar materials AISI 304 And monel alloy 400

1. INTRODUCTION 1.1 WELDING

Welding is a metal joining process that is used for joining two or more similar metallic work pieces (or thermoplastics) by the application of heat.

It finds its application in a large number of industrial processes. Welding can be done either by melting and solidifying metals or by the application of pressure and heat. The quality and lifetime of weld can be improved by Figure 1.1 plasma arc welding Setup providing after-treatment to the weld. High Frequency Impact Treatment (HiFIT) is an example of after-treatment provided The plasma arc welding is method wherever a coalescence is to welded joints to improve their fatigue strength. Welding can generated with the temperature which is developed from a be used to produce five main joints. These joints can be sub- special setup between a alloy and the water- categorized. The five main welded joints are listed below: cooled nozzle (Non transferred ARC) or between a tungsten alloy electrode and the job (transferred ARC). In this type of  Lap Joint winding, there are three types of gas supplies being utilized  Butt Joint namely plasma gas, , and a back-purge gas.  Tee Joint Plasma gas supplies throughout the nozzle turn into ionized.  Edge Joint The shielding gas supplies throughout the external nozzle &  Corner Joint protects the join from the environment. Back-Purge gas is mainly used when particular materials are being used. 1.2 PLASMA ARC WELDING 1.2.1 Equipment used in Plasma ARC Welding The PAW (Plasma arc welding) method is related to GTAW (). This arc can be formed The equipment used in the PAW includes the following. among the metal as well as an electrode. The major difference  The power supply used in the PAW is a DC power among the PAW and GTAW is that in PAW, the is source, and the suitable voltage for this type of welding is capable in placing the electrode in the torch’s body; so this 70 volts otherwise above. will allow the PAW to be divided from the protecting gas.  The typical welding parameters are voltage, current, and Afterward, the plasma is fed throughout a nozzle which will gas flow rate. These parameter values can be ranges like compress the arc to force the plasma away at high speed as the current is 500A, voltage is 30V to 250V, the speed of well as temperature. cutting is: 0.1 to7.5 m/min, the thickness of the plate is up to 200mm, required power is 2KW to 200KW, the rate of

IJESC, March 2021 27824 http:// ijesc.org/ material removal is 150 cm3/min, and plas ma velocity is  PAW is used to coating otherwise welding on the 500m/sec turbine blade.  Current limiting resistors, as well as a high-frequency generator, are used for arc ignition. 1.3 MILD STEEL  The plasma torch includes an electrode as well as water- cooling arrangement, and these are used to save the Conquest Steel & Alloys is one of the best nozzle & the electrode’s lifespan from dissolving due to manufacturer, supplier, and exporter of high quality industrial the extreme heat generated while welding. products. We are a popular trader, wholesaler of mild Steel  The fixture is necessary to avoid atmospheric pollution Plates in all over the globe. We follow all standards and from the molten metal beneath bead. specifications and also in different types. We manufacture and  Shielding gas is used for protecting the arc region from supply our product according to customer’s demand. The MS the atmosphere PLATES are available in different types, thicknesses, lengths, radius, dimensions, diameters, and many more. There are 1.2.2 Plasma ARC Welding Types different types of plates are available like polished, hot rolled and cold rolled plates, and so on. The plates are used in Plasma arc welding is classified into two types such as various industries because of good workability, formability, easy to fabricate, durability, easy to install, mach inability, 1) Transferred PAW weld ability, etc. The transferred PAW method uses direct polarity DC current. And in this method, the tungsten electrode can be MILD STEEL PLATE SPECIFICATION: allied to the –ve terminal and the metal can be allied to the +ve Thickness: 5mm-150mm terminal. The arc produces among tungsten electrode as well Width: 1000mm-4500mm as work portion. In this kind of method, both arc and plasma Length: 3000mm-18000mm moved toward the work portion, which will enhance the Process: Hot-Rolled (HR) heating capacity of the method. This type of PAW can be used to join solid sheets. Carbon steel is steel in which the main interstitial alloying

constituent is carbon in the range of 0.12-2.0%.the American 2) Non-transferred PAW iron and steel institute (AISI) definition says. Steel is The Non-transferred PAW method used direct considered to be carbon steel when no minimum content is polarity DC current. And in this method the tungsten electrode specified or required for chromium, cobalt, molybdenum, can be connected to the –ve and the nozzle can be connected nickel niobium, titanium, tungsten, or any other element to be to the +ve pole. The arc generates among the nozzle as well as added to obtain a desired alloying effect. tungsten electrode within the torch, which will enhance the ionization of the gas within the torch. And the torch will 1.4 SWARM ALGORITHM transfer the ionized gas for further procedure. This type of

PAW can be used to join thin sheets. Swarm intelligence is the discipline that deals with

natural and artificial systems composed of many individuals 1.2.3 Advantages of PAW that coordinate using decentralized control and self- The advantages of PAW mainly include the following. organization. In particular, the discipline focuses on the  Power consumption is low collective behaviors that result from the local interactions of  Welding speed is high, so it can simply utilize to join the individuals with each other and with their environment. thick and hard work pieces. Examples of systems studied by swarm intelligence are  Penetration rate and strong arc are high. colonies of ants and termites, schools of fish, flocks of birds,  It can function at little amperage. herds of land animals. Some human artifacts also fall into the  The arc arrangement doesn’t affect by the distance domain of swarm intelligence, notably some multi-robot among tool as well as the work piece. systems, and also certain computer programs that are written  By using this method, the more steady arc can be to tackle optimization and data analysis problems. produced. 1.4.1 Taxonomy of Swarm Intelligence 1.2.4 Disadvantages of PAW The disadvantages of PAW mainly include the following. Swarm intelligence has a marked multidisciplinary  The process is noisy. character since systems with the above mentioned  Equipment cost is high. characteristics can be observed in a variety of domains.  High expertise labor required. Research in swarm intelligence can be classified according to  Radiation is more. different criteria.

1.2.5 Applications of PAW Natural vs. Artificial: It is customary to divide swarm The applications of PAW mainly include the following. intelligence research into two areas according to the nature of  PAW can be used in industries like aerospace as well the systems under analysis. We speak therefore as marine of natural swarm intelligence research, where biological  PAW is used to join stainless tubes and pipes systems are studied; and of artificial swarm intelligence,  This type of welding is mostly applicable for where human artifacts are studied. electronic industries.  PAW is mainly used to fix tools, mold and die. Scientific vs. Engineering: An alternative and somehow more informative classification of swarm intelligence research can be given based on the goals that are pursued: we can identify

IJESC, March 2021 27825 http:// ijesc.org/ a scientific and an engineering stream. The goal of the  the interactions among the individuals are based on scientific stream is to model swarm intelligence systems and simple behavioral rules that exploit only local information to single out and understand the mechanisms that allow a that the individuals exchange directly or via the system as a whole to behave in a coordinated way as a result environment (stigmergy); of local individual-individual and individual-environment  the overall behaviour of the system results from the interactions. interactions of individuals with each other and with their environment, that is, the group behavior self-organizes. NATURAL/SCIENTIFIC: The characterizing property of a swarm intelligence system is In a now classic experiment done in 1990, its ability to act in a coordinated way without the presence of a Deneubourg and his group showed that, when given the choice coordinator or of an external controller. Many examples can between two paths of different length joining the nest to a food be observed in nature of swarms that perform some collective source, a colony of ants has a high probability to collectively behavior without any individual controlling the group, or choose the shorter one. Deneubourg has shown that this being aware of the overall group behavior. Notwithstanding behavior can be explained via a simple probabilistic model in the lack of individuals in charge of the group, the swarm as a which each ant decides where to go by taking random whole can show an intelligent behavior. This is the result of decisions based on the intensity of pheromone perceived on the interaction of spatially neighboring individuals that act on the ground, the pheromone being deposited by the ants while the basis of simple rules. moving from the nest to the food source and back.

ARTIFICIAL/SCIENTIFIC: CLUSTERING BY A 1.4.3 Studies and Applications of Swarm Intelligence SWARM OF ROBOTS This section briefly presents a few examples of Several ant species cluster corpses to form scientific and engineering swarm intelligence studies. cemeteries. Deneubourg et al. (1991) were among the first to 1.4.3.1 Clustering Behavior of Ants propose a distributed probabilistic model to explain this clustering behavior. In their model, ants pick up and drop Ants build cemeteries by collecting dead bodies into items with probabilities that depend on information on corpse a single place in the nest. They also organize the spatial density which is locally available to the ants. Beckers et al. disposition of larvae into clusters with the younger, smaller (1994) have programmed a group of robots to implement a larvae in the cluster center and the older ones at its periphery. similar clustering behavior demonstrating in this way one of This clustering behavior has motivated a number of scientific the first swarm intelligence scientific oriented studies in which studies. Scientists have built simple probabilistic models of artificial agents were used. these behaviors and have tested them in simulation (Bonabeau et al. 1999). NATURAL/ENGINEERING: EXPLOITATION OF COLLECTIVE BEHAVIORS OF ANIMAL SOCIETIES 1.4.3.2 Nest Building Behavior of Wasps and Termites Wasps build nests with a highly complex internal A possible development of swarm intelligence is the structure that is well beyond the cognitive capabilities of a controlled exploitation of the collective behavior of animal single wasp. Termites build nests whose dimensions (they can societies. No example is available in this area of swarm reach many meters of diameter and height) are enormous intelligence although some promising research is currently in when compared to a single individual, which can measure as progress: For example, in the Leurre project, s mall insect-like little as a few millimeters. Scientists have been studying the robots are used as lures to influence the behavior of a group of coordination mechanisms that allow the construction of these cockroaches. The technology developed within this project structures and have proposed probabilistic models exploiting could be applied to various domains including agriculture and stigmergic communication to explain the insects' behavior cattle breeding. 1.4.3.3 Flocking and Schooling in Birds and Fish

ARTIFICIAL/ENGINEERING: SWARM-BASED DATA ANALYSIS Flocking and schooling are examples of highly coordinated group behaviors exhibited by large groups of Engineers have used the models of the clustering birds and fish. Scientists have shown that these elegant behavior of ants as an inspiration for designing data swarm-level behaviors can be understood as the result of a mining algorithms. A seminal work in this direction was self-organized process where no leader is in charge and each undertaken by Lumer and Faieta in 1994. They defined an individual bases its movement decisions solely on locally artificial environment in which artificial ants pick up and drop available information: the distance, perceived speed, and data items with probabilities that are governed by the direction of movement of neighbors. similarities of other data items already present in their neighborhood. The same algorithm has also been used for 1.4.3.4 Ant Colony Optimization solving combinatorial optimization problems reformulated as clustering problems Ant colony optimization (Dorigo, Maniezzo and

Colorni 1991; Dorigo and Stützle 2004) is a population-based 1.4.2 Properties of a Swarm Intelligence System metaheuristic that can be used to find approximate solutions to The typical swarm intelligence system has the following difficult optimization problems. It is inspired by the above- properties: described foraging behavior of ant colonies. In ant colony  it is composed of many individuals; optimization (ACO), a set of software agents called "artificial ants" search for good solutions to a given optimization  the individuals are relatively homogeneous (i.e., they problem transformed into the problem of finding the minimum are either all identical or they belong to a few typologies); cost path on a weighted graph. IJESC, March 2021 27826 http:// ijesc.org/ 1.4.3.5 Particle Swarm Optimization employed an electric power supply to create an arc which melts the base metal to form a molten pool .The filler wire is Particle swarm optimization (Kennedy and Eberhart then either added automatically (GMAW) or manually 1995; Kennedy, Eberhart and Shi, 2001) is a population based (SMAW & GTAW) and The molten pool is allowed tocool. stochastic optimization technique for the solution of Finally, all of the methods use some type of flux or gas to continuous optimization problems. It is inspired by social create an insert environment in which the molten pool can behaviors in flocks of birds and schools of fish. In particle solidify without oxidizing. swarm optimization (PSO), a set of software agents called particles search for good solutions to a given continuous 3.2. Plasma Arc Welding (PAW) optimization problem 1.4.3.6 Swarm-based Network Management Plasma welding is very similar to TIG as the arc is The first swarm-based approaches to network formed between a pointed tungsten electrode and the work management were proposed in 1996 by Schoonderwoerd et piece. However, by positioning the electrode within the body al., and in 1998 by Di Caro and Dorigo. Schoonderwoerd et al. of the torch, the plasma arc can be separated from the proposed Ant-based Control (ABC), an algorithm for routing shielding gas envelope. Plasma is then forced through a fine- and load balancing in circuit-switched networks; Di Caro and bore copper nozzle which constricts the arc. Three operating Dorigo proposed Ant Net, an algorithm for routing in packet- modes can be produced by varying bore diameter and plasma switched networks. While ABC was a proof-of-concept, Ant gas flow rate: Net, which is an ACO algorithm, was compared to many state- of-the-art algorithms and its performance was found to be competitive especially in situation of highly dynamic and stochastic data traffic as can be observed in Internet-like networks.

1.4.3.7 Cooperative Behavior in Swarms of Robots There are a number of swarm behaviors observed in natural systems that have inspired innovative ways of solving problems by using swarms of robots. This is what is called swarm robotics. In other words, swarm robotics is the application of swarm intelligence principles to the control of swarms of robots. As with swarm intelligence systems in general, swarm robotics systems can have either a scientific or an engineering flavor.

2. PROBLEM IDENTIFICATIONS

Losses of life and property due to catastrophic failure Figure 3.1 Plasma Arc Welding (PAW) of structures are often traced to defective welds. However, major advances have taken place in welding science and Microplasma: 0.1to15A. technology in the last few decades. With the development of new methodologies at the crossroad of basic and applied The microplasma arc can be operated at very low welding sciences, the promise of science-based tailoring of currents. The columnar arc is stable even when arc length is composition, structure, and properties of the elements may be varied up to 20mm. fulfilled. This will require resolution of several contemporary issues and problems concerning the structure and properties of Medium current: 15to200A. the elements as well as intelligent control and automation of the welding processes. At higher currents, from 15 to 200A, the process characteristics of the plasma arc are similar to the TIG arc, but 3. INTRODUCTION TO WELDING because the plasma is constricted, the arc is stiffer. Although the plasma gas flow rate can be increased to improve weld A weld is made when separate pieces of material to be pool penetration, there is a risk of air and shielding gas joined combine and form one piece when heated to a entrainment through excessive turbulence in the gas shield. temperature high enough to cause softening or melting. Filler material is typically added to strengthen the joint. Welding is Keyhole plasma: over 100A. used extensively in all sectors or manufacturing, from earth moving equipment to the aerospace industry. Welding is a By increasing welding current and plasma gas flow, a very dependable, efficient and economic method for permanently powerful plasma beam is created which can achieve full joining similar metals. In other words, you can weld steel to penetration in a material, as in laser or electron beam welding. steel or aluminum to aluminum, but you cannot weld steel to During welding, the hole progressively cuts through the metal aluminum using traditional welding processes. with the molten weld pool flowing behind to form the weld bead under surface tension forces. This process can be used to 3.1 WELDING PROCESSES weld thicker material (up to 10mm of ) in a single pass. . The most popular processes are shielding metal arc welding (SMAW), (GMAW) and gas tungsten arc welding (GTAW). All of these methods IJESC, March 2021 27827 http:// ijesc.org/ 3.2.1 Power source Keyhole welding The plasma arc is normally operated with a DC, This has several advantages which can be exploited: drooping characteristic power source. Because its unique deep penetration and high welding speeds. Compared with the operating features are derived from the special torch TIG arc, it can penetrate plate thicknesses up to l0mm, but arrangement and separate plasma and shielding gas flows, a when welding using a single pass technique, it is more usual to plasma control console can be added on to a conventional TIG limit the thickness to 6mm. The normal methods is to use the power source. Purpose-built plasma systems are also available. keyhole mode with filler to ensure smooth weld bead profile The plasma arc is not readily stabilized with sine wave AC. (with no undercut). Arc resignation is difficult when there is a long electrode to work piece distance and the plasma is constricted, Moreover, excessive heating of the electrode during the positive half- 3.3 PROCEDURE FOR WELDING IN MILD STEEL cycle causes balling of the tip which can disturb arc stability. MIG welding is an arc welding process in which a

continuous solid wire electrode is fed through a welding gun 3.2.2 Arc starting and into the weld pool, joining the two base materials Although the arc is initiated using HF, it is first together. A shielding gas is also sent through the welding gun formed between the electrode and plasma nozzle. This 'pilot' and protects the weld pool from contamination. in fact, MIG arc is held within the body of the torch until required for stands for “Metal Inert Gas” the technical name for it is metal welding then it is transferred to the workpiece. The pilot arc arc welding (or GMAW),and the slang name for it is “wire system ensures reliable arc starting and, as the pilot arc is welding”.MIG welding process enables the home-hobby,aritist maintained between welds, it obviates the need for HF which , farmer/rancher, motorsports enthusiast or DIY welder to may cause electrical interference. make most types of fabrication and maintenance/repair welds on material from 24-gauge up to1/2-in.thick.in addition to 3.2.3 Electrode flexibility, many people turn to MIG welding because they’ve The electrode used for the plasma process is heard that is an easy process to learn. tungsten-2%thoria and the plasma nozzle is copper. The electrode tip diameter is not as critical as for TIG and should 3.3.1 Mild and Low Carbon Steel be maintained at around 30-60 degrees. The plasma nozzle bore diameter is critical and too small a bore diameter for the Mild steel also known as plain carbon steel is now current level and plasma gas flow rate will lead to excessive the most common form of steel because its price is relatively nozzle erosion or even melting. It is prudent to use the largest low while it provides material properties that are acceptable bore diameter for the operating current level. for many applications. Low carbon steel contains approximately 0.05%-0.25% carbon making it malleable and Note: too large a bore diameter, may give problems with arc ductile. stability and maintaining a keyhole. 3.2.4 Plasma and shielding gases 3.3.2 Higher-Carbon Steels

The normal combination of gases is argon for the Carbon steels which can successfully undergo heat- plasma gas, with argon plus 2 to 5% hydrogen for the treatment have a carbon content in the range of 0.30-1.70% by shielding gas. Helium can be used for plasma gas but because weight. Trace impurities of various other elements can have a it is hotter this reduces the current rating of the nozzle. significant effect on the quality of the resulting steel. Trace Helium's lower mass can also make the keyhole mode more amounts of sulfur in particular make the steel red-short, that is, difficult. brittle and crumbly at working temperature. Low-alloy carbon 3.2.5 Applications steel, such as A36 grade, contains about 0.05% sulfur and melts around 1,426-1,538 oC. Manganese is often added to Microplasma welding improve the harden ability of low-carbon steels. These Microplasma was traditionally used for welding thin additions turn the material into low-alloy steel by some sheets (down to 0.1 mm thickness), and wire and mesh definitions, but AISI’s definition carbon steel allows up to sections. The needle-like stiff arc minimizes arc wander and 1.65%manganese weight. distortion. Although the equivalent TIG arc is more diffuse, the newer transistorized (TIG) power sources can produce a 3.4 WELD AND OF very stable arc at low current levels. MILD STEEL Weld ability is defined as the capacity of a material to Medium current welding be welded under the imposed fabrication conditions into a specific, suitability designed structure and to perform When used in the melt mode this is an alternative to satisfactorily in the intended service. carbon steel is generally conventional TIG. The advantages are deeper penetration considered to be quite wieldable, particularly when the carbon (from higher plasma gas flow), and greater tolerance to content is below 0.35%, which it is by specification in all surface contamination including coatings (the electrode is available to weld carbon steel satisfactorily, with properties within the body of the torch). The major disadvantage lies in and composition comparable in the weld and the base the bulkiness of the torch, making manual welding more material. the term weld ability is also used in a narrower sense difficult. In mechanized welding, greater attention must be to mean the ease with which a material can be welded without paid to maintenance of the torch to ensure consistent cracking or other discontinuities. It is this meaning that is performance. more relevant to the welding qualification.

IJESC, March 2021 27828 http:// ijesc.org/ 3.5 ALLOYING ELEMENTS IN MILD STEELS Tungsten (W) Used in small amounts, tungsten combines with the free Alloying elements are added to effect changes in the carbides in steel during heat treatment, to produce high wear properties of steels. The basis of this section is to cover some resistance with little or no loss of toughness. High amounts the different alloying elements added to the basis system of combined with chromium gives steel a property known as red iron an carbon, and what they do to change the properties of hardness effectiveness of steel. As I’ve already started, the presence of carbon in iron is Copper (C) necessary to make steel. Carbon is essential to the formation The addition of copper in amounts of 0.2 to 0.5 percent of commentate (as well as other carbides), and to the primarily improves steels resistance to atmospheric corrosion. formation of pearlite, spheroidite, bainite, and iron-carbon It should be noted that with respect to martens tic, with martens tic being the hardest of the micro- knife steels, copper has a detrimental effect to surface quality structure, and the structure sought after by knife makers. and to hot-working behavior due to migration into the grain The steels of interest to knife makers generally boundaries of the steel. contain between 0.5 and 1.5% carbon. They are described follows: Niobium (Nb) o Low carbon: under 0.4% In low carbon alloy steels Niobium lowers the o Medium carbon: 0.4-0.6% transition temperature and aids in a fine grain structure. o High carbon: 0.7-1.5% Niobium retards tempering and can decrease the harden ability of steel because it forms very stable carbides. This can mean a Carbon is the single most important alloying element in steel. reduction in the amount of carbon dissolved into the austenite during heat treating. 3.6 EFFECTS OF ALLOYING AND IMPURITIES IN CARBON STEELS Boron (B) Boron can significantly increase the harden ability of Manganese (Mn) steel without loss of ductility. Its effectiveness is most Manganese slightly increases the strength of ferrite, and noticeable at lower carbon levels. The addition of boron is also increases the hardness penetration of steel in the quench usually in very small amounts ranging from 0.0005 to 0.003 by decreasing the critical quenching speed. This also makes percent. the steel more stable in the quench. Titanium (Ti) Chromium (Cr) This element, when used in conjunction with Boron, As with manganese, chromium has a tendency to increase increases the effectiveness of the Boron in the harden ability hardness penetration. This element has many interesting of steel. effects on steel. When 5 percent chromium or more is used in conjunction with manganese, the critical quenching speed is 3.7 MONEL METAL reduced to the point that the steel becomes air hardening. Monel 400 is a nickel-copper alloy (about 67% Ni – Chromium can also increase the toughness of steel, as well as 23% Cu) that is resistant to sea water and steam at high the wear resistance. Probably one of the most well-known temperatures as well as to salt and caustic solutions. Alloy 400 effects of chromium on steel is the tendency to resist staining is a solid solution alloy that can only be hardened by cold and corrosion.. working. This nickel alloy exhibits characteristics like good corrosion resistance, good weld ability and high strength. Silicon (Si)

Silicon is used as a deoxidizer in the manufacture of 3.7.1 Characteristics of Monel 400 steel. It slightly increases the strength of ferrite, and when Resistant to seawater and steam at high temperatures used in conjunction with other alloys can help increase the  Excellent resistance to rapidly flowing brackish water toughness and hardness penetration of steel. or seawater

 Excellent resistance to stress corrosion cracking in Nickel (Ni) Nickel increases the strength of ferrite, therefore most freshwaters increasing the strength of the steel. It is used in low alloy  Particularly resistant to hydrochloric and hydrofluoric steels to increase toughness and harden ability. Nickel also acids when they are de-aerated tends to help reduce distortion and cracking during the  Offers some resistance to hydrochloric and sulfuric quenching phase of heat treatment acids at modest temperatures and concentrations, but is seldom the material of choice for these acids Molybdenum (Mo)  Excellent resistance to neutral and alkaline salt Molybdenum increases the hardness penetration of  Resistance to chloride induced stress corrosion steel, slows the critical quenching speed, and increases high cracking temperature tensile strength.  Good mechanical properties from sub-zero temperatures up to 1020° F Vanadium (Va)  High resistance to alkalis Vanadium helps control grain growth during heat C Mn S Si Ni Cu Fe treatment. By inhibiting grain growth it helps increase the toughness and strength of the steel. .3 2. .0 .5 63 28. 2. 0 max 00 24 0 max .0 min 0-34.0 50 max max max

IJESC, March 2021 27829 http:// ijesc.org/ 3.7.2 Corrosion Resistant Monel 400 any standard design into a robust one. Simply put, DOE helps This nickel alloy is attacked in sulfur-bearing gases to pin point the sensitive parts and sensitive areas in designs above approximately 700° F and molten sulfur attacks the that cause problems and produce robust and higher yield alloy at temperatures over approximately 500° F. designs prior going into production. Monel 400 offers about the same corrosion resistance as nickel but with higher maximum working pressures and temperatures 4.2.1 DOE Problem Areas and at a lower cost due to its superior ability to be machined. There are four general engineering problem areas in 3.7.3 Applications is Monel 400 Used which DOE may be applied.  Marine engineering  Chemical and hydrocarbon processing equipment  Comparative  Gasoline and freshwater tanks  Screening/Characterizing  Crude petroleum stills  Modeling  De-aerating heaters  Optimizing  Boiler feed water heaters and other heat exchangers  Valves, pumps, shafts, fittings, and fasteners 4.2.2 Orthogonal Array  Industrial heat exchangers  Chlorinated solvents In mathematics, in area of combinational designs, an orthogonal array is tuple” (array) whose entries come from a 3.7.4 Fabrication with Monel 400 fixed finite set of symbols (typically, 1, 2, …, n}), arranged in  Alloy 400 can easily be welded by gas-tungsten arc, gas such a way that there is an integert so that for every equation metal arc or shielded metal arc processes using of t columns of the table, all ordered t=tuples of the symbols, appropriate filler metals. There is no need for post weld formed by equating the entries in each row restricted to these heat treatment, however, thorough cleaning after welding columns, appear the same number of times. The number t is is critical for optimum corrosion resistance, otherwise called the strength of the orthogonal array. Here is a tuple there is the risk of contamination and embrittlement. example of an orthogonal array with symbol set {1, 2}:

 Finished fabrications can be produced to a wide range of mechanical properties when proper control of the amount

of hot or cold working and the selection of appropriate

thermal treatments is done.

 Like most other nickel alloys, Monel 400 is typically

tough to machine and will work harden. However,

excellent results can e obtained if you make the correct

choices for tooling and .

4. OPTIMIZATION

In a typical optimization problem, the goal is to find the values of controllable factors determining the behavior of a Figure 4.1 Orthogonal array system (e.g., a physical production process, an investment scheme) that maximize weld bead width and height. The Notice that the four ordered pairs (2-tuples) formed by simplest problems involve functions (systems) of a single the rows restricted to first and third columns, namely (1, 1), (2, variable (input factor) and may be solved with differential 1), (1, 2), and (2, 2) are all the possible ordered pairs of the calculus. two element set and each appears exactly once. The second

and third columns would give, (1, 1), (2, 1), (2, 2), and (1, 2); 4.1 SWARM ALGORITHM again, all possible ordered pairs each appearing once.

In the early of 1990s, several studies regarding the 4.2.3 L9 Orthogonal Array social behavior of animal groups were developed. These studies showed that some animals belonging to a certain Orthogonal array testing is a black box testing group, that is, birds and fishes, are able to share information technique that is systematic, statistical way of software testing. among their group, and such capability confers these animals a It is used when the number of inputs to the system is relatively great survival advantage. Inspired by these works, Kennedy small, but too large to allow for exhaustive testing of every and Eberhart proposed in 1995 the PSO algorithm, a met possible input to the systems. It is particularly effective in heuristic algorithm that is appropriate to optimize nonlinear finding errors associated with faulty logic within computer continuous functions. The author derived the algorithm software systems. Orthogonal arrays can be applied in user inspired by the concept of swarm intelligence, often seen in interface testing, system testing, regression testing and animal groups, such as flocks and shoals. performance testing. The permutations of factors levels

comprising an angle treatment are so chosen that their 4.2 DESIGN OF EXPERIMENTS responses are uncorrelated and therefore such treatment gives

a unique piece of information. The net effects of organizing Design of Experiments (DOE) techniques enables the experiments in such treatments are that the same piece of designers to determine simultaneously the individual and information is rethread in the minimum number of interactive effects of many factors that could affect the output experiments. results in any design. DOE also provides a full insight of interaction between design elements; therefore, it helps turn

IJESC, March 2021 27830 http:// ijesc.org/ suitable allowances are taken using welding so that it can be machined to dimension required for making weld joints.

Figure 4.2 L9 orthogonal arrays

4.2.4 PARAMETERS SELECTED The parameters are selected wire feed rate, voltage and current with 3 levels of values with varying welding speeds. The selected parameters are optimized in L9 orthogonal array generated using MINITAB 2010 software.

INPUT PARAMETERS Figure 5.1 plasma arc welding work piece S.N 1 2 3 O PARAMETERS 5.2 CHEMICAL PROPERTIES 1 WV(volts) 30 35 40 1) Element 2) Weight 2 WC(m/min) 6.2 8.6 9.14 Iron 66.74 - 71.24% (Balance)

3 TIME(Sec) 42 48 50 Chromium 17.5 - 19.5%

4 NTPD(mm) 13 15 18 Nickel 8 - 10.5% Manganese 2%

Table 4.1 Input parameters Silicon 1%

Nitrogen 0.11% S.NO X1 X2 X3 X4 Carbon 0.07% 1 1 1 1 1 Phosphorus 0.05%

2 1 2 2 2 Sulphur 0.03%

3 1 3 3 3 Table 5.1 Chemical composition of AISI 304

4 2 1 2 3 Element Weight 5 2 2 3 1 Nickel, Ni Remainder 6 2 3 1 2 Copper, Cu 28-34

7 3 1 3 2 Iron, Fe 2.5 max

8 3 2 1 3 Manganese, Mn 2 max

9 3 3 2 1 Silicon, Si 0.5 max

Carbon, C 0.3 max Table 4.2 L9 Orthogonal array coded value Sulphur, S 0.024 5.EXPERIMENTAL PROCEDURE

5.1 MATERIALS Table 5.2 Chemical composition of Monel 400 Alloy (UNS This project the works on Plasma Arc welding N04400) process dissimilar materials AISI 304 And monel alloy 400 joints. Three plate of dimension 100mm x 50mm x 5 mm with

IJESC, March 2021 27831 http:// ijesc.org/ The electrode used for the plasma process is tungsten-2%thoria and the plasma nozzle is copper. The electrode tip diameter is not as critical as for TIG and should be maintained at around 30-60 degrees. The plasma nozzle bore diameter is critical and too small a bore diameter for the current level and plasma gas flow rate will lead to excessive nozzle erosion or even melting. It is prudent to use the largest bore diameter for the operating current level.

Note: too large a bore diameter, may give problems with arc stability and maintaining a keyhole.

Figure 5.4 Sample Preparations for Testing

5.8 WELD BEAD MEASUREMENTS

Figure 5.2 Tungsten Electrode

5.5 PLASMA AND SHIELDING GASES The normal combination of gases is argon for the plasma gas, with argon plus 2 to 5% hydrogen for the Figure 5.5 weld bead measurements shielding gas. Helium can be used for plasma gas but because it is hotter this reduces the current rating of the nozzle. 5.8.1 Vernier Caliper Helium's lower mass can also make the keyhole mode more A vernier scale is device that lets the user measure difficult. more precisely that could be done unaided when reading a uniformly divided straight or circular measurement scale. It is 5.6 WELD PREPARATION a scale that indicates where the measurement lies in between Weld preparation may be carried out by abrasive two of the marks on the main scale. Venire are common on cutting or machining. Seam edges(groove faces) prepared by sextants used in navigation, scientific instruments used to abrasive cutting shall be finished by machining (e.g. grinding) conduct experiments, machinists machining tools used to work if a detrimental effect on the welded joint as a result of the materials to fine tolerances, and on theodolites used cutting operation cannot be ruled out.

Figure 5.6Vernier caliper

5.8.2 Height Gauge The height gauge is a measuring device used either of determining the height of object, or for marking of items to be worked on. These measuring tools are used in or metallurgy to either set or measure vertical distance to find Figure 5.3 Welding Materials the height of people in which context they are called stadiometers. Height gauge may also be used to measure the 5.7 SAMPLE PREPARATION FOR TESTING height of an object by using the underside of the scriber as the datum. This adjustment allows different scribers or probes to After welding the welded material to be prepared by be used, as well as adjusting for any errors in a damaged or testing in micro hardness testing and optical microscope (OM) sharpened probe. testing. In that purpose the specimen to be prepared by using cutter, in the size 100mm x50mm x 5mm for OM test and 100mm x 50mm x 5mm for micro hardness testing respectively. The prepared samples are polished

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Figure 5.7 Vernier height gauges

5.9 TESTING

5.9.1 Microstructure Testing Figure 5.9 Vickers hardness testing A microscope is in principle nothing else than a simple lens system for magnifying small objects. The first The term micro hardness test usually refers to static lens, called the objective, has a short focal length (a few mm), indentations made with loads not exceeding 1 kgf. The This information can then be used to improve material indenter is either the Vickers diamond pyramid or the processing and properties which form the foundation of elongated diamond pyramid. materials science and engineering and creates an image of the object in the intermediate image plane. This image in turn can 6. RESULT AND DISCUSSION be looked at with another lens, the eye-piece, which can provide further magnification. 6.1 MATHEMATICAL MODELING The first order mathematical model was developed using design expert software and subsequently statistical analysis was carried out. For three variables, the quadratic response ‘y’ is described in the form of the following equation

2 Y=bo+∑ bixi +∑ bi xix +∑ bii xi

Where bo is the intercept term, bi is the linear term, bii is the quadratic term and is the interaction term in the present study, the response, i.e penetration

The regression equation is

Height = 11.1 + 1.30 x1 + 0.325 x2 - 0.213 X3 - 0.262 Width = 4.88 - 0.467 + 0.317 - 0.283 X4 X1 X2 + 0.117 Figure 5.8 Microstructure testing X3 X4

6.3 MAIN EFFECT PLOTS 5.9.2 Chemical Etching

There are two types of mechanis m: physical etching and relies on momentum transfer from particles hitting and eroding the surface and wet/dry etching. The removal of material from a substrate by chemical reaction or by ion bombardment is referred as an etch process. The material that is not masked is removed resulting in patterned regions. The rate of material removal is known as etch rate and is the thickness removed per unit time (nm/min).for high production throughput, we need etch rates above 50nm/min. depending on the etch process material, the etching can occur in both horizontal and vertical direction.

5.9.3 Vickers Hardness Testing

Micro indentation hardness testing, more commonly Figure 6.1 Residual plots for height (but incorrectly) called micro hardness testing, is widely used to study fine scale changes in hardness, either intentional or accidental. Heat theatres have utilized the technique for many years to evaluate the success of surface hardening treatment or to detect and access decarburization.

IJESC, March 2021 27833 http:// ijesc.org/ For Sample A2: The result of sample A2 and test results are shown below,

Welding Wire feed Welding

voltage rate speed NTPD

SAMPLE (cm/m

(V ) (m/mm) m) (mm)

A2 30 8.6 48 15

Table 6.2 welding parameters for sample A2

Figure 6.2 Main effect plots for means(height)

Fig 6.5 parent metal of sample A2 with 100x magnification

6.5 RESULTS FOR VICKERS HARDNESS TESTING Figure 6.3 Main effects plot for SN ratio The micro hardness was measured using Vickers’s 6.4 RESULTS FOR MICROSTRUCTURE TESTING hardness machine at 500g load applied for 15s at various locations in each specimen. The technical specifications of the Austenitic Stainless Steel is widely used in variety Vickers’s hardness machine are, of industries. In order to check out the structure of the material microstructure is considered to be one of the most important 6.6 GRAPHICAL REPRESENTATION mechanical properties. Microstructure of parent material after welding, heat affected zone, and welded zone of four samples are shown below respectively. The results for the microstructure of weld metal mild steel 304 represent the smaller grain size. For Sample A1:

The result of sample A1 and test results are shown below

Welding Wire feed Welding SAMPL voltage rate speed NTPD E (V ) (m/mm) (cm/mm) (mm)

A1 30 6.2 42 13 Figure 6.6 Hardness test sample 1

Table 6.1 welding parameters for sample A

Figure 6.7 Hardness test sample 2 Fig 6.4 parent metal of sample A1 with 500x magnification

IJESC, March 2021 27834 http:// ijesc.org/ bead profile of the selected optimum experiments output. From this project work the optimum experiments 6 and 8 and bead overlap percentage 60% were identified.

8.REFERENCE

[1] Patricio F. Mendez, Thomas W.Eagar, Welding Processes for Aeronatics, Advanced Materials & Processes, May 2019.

[2] Jean Marie Fortain, Plas ma welding evolution & challenges, Air Liquide CTAS, Welding and Cutting Research Figure 6.8 Hardness test sample 3 Center, 95315 Cergy Pontoise France. Feb 2018.

[3] Kimiyuki Nishiguchi and Kazumasa Tashiro,(1970) , Series Arcing in Plasma Arc Welding, Japan welding society, pp 59-69.

[4] K.Tsuchiya, K.Kishimoto, T.Matsunaga, E.Nakano,(1973), Plasma Arc Welding for thick plate (part-1), Japan welding society, pp 554-566.

[5] Kunio Narita, (1975), Plas ma arc welding of pipelines: A study to optimize welding conditions for horizontal fixed joints of mild steel pipes, Int. J. Pres. Ves. & Piping 3: pp 233-266.

Figure.6.9 Comparison of hardness for three samples [6] V. I. Astakhin, A. S. Bychkov, V. A. Konovalov and  Due to the increase of Wire feed rate, Welding R. M. Meirov, (1977), Plas ma Arc Welding of Aluminium voltage, Welding speed, and NTPD there is an alloy cryogenic piping, Japan welding society, No.2, pp 26-28. Increase and Decrease of the Hardness. [7] Katsunori Inoue and De-Fu He,(1984), Penetartion– Self-Asaptive Free Frequency Pulsed Plasma Arc Welding  In the sample A1 the Hardness value falls and Process Controlled with Photocell Sensor, Transactions of due to the increase of weld bead overlap the hardness value raises. JWRI, Vol. 13,No. 1:pp 7-11.

[8] T. S. Baker, (1985), Fatigue crack propagation and  In the sample A2 the Hardness value raises at the fracture toughness of plasma arc welded Ti-6AL-4V alloy, weld bead overlap of 50% to 80% Royal aircraft establishment, Technical report no: 85066.

 In the sample A3 the Hardness value lowers [9] T. Ishida, (1987), Interfacial phenomena of plasma at the 10 to 30% and from 40 to 70% weld arc welding of mild steel and aluminum, Journal of materials bead overlap the Hardness value raises science, 22 : pp 1061- 1066.

7. CONCLUSION [10] S. C. Tam, L. E. Lindgren and L. J. Yang, (1989),

Computer simulation of tempaerture fields in mechanized It was understood from the earlier works that most of plasma arc welding, Journal of Mechanical working the works in Plasma Arc Welding and associated phenomena technology,19:pp 23-33. are towards modeling of plasma arc, temperature & heat transformation and process parameter optimization to get the [11] John W, McKelliget,(1990), Numerical computation desired weld quality. Very few works had happened especially of coupled heat transfer, fluid flow and electromagnetism: The in Micro Plasma Arc Welding of thin sheets. A three-level, Inductivity coupled plasma torch, Advanced computational four-factors are welding voltage, wire feed rate, welding speed methods in heat transfer, vol.3. and nozzle to plate distance experimental runs are conducted.

The swarm algorithm L9 design matrix used to develop of [12] John W, McKelliget, (1992), A mathematical model mathematical models to predict the clad bead geometry for of the spheroidization of porous agglomerate particles in dissimilar materials AISI 304 And monel alloy 400 PAW. The thermal plasma torches, Thermal Plasma Applications in predicted results using mathematical models are very close to Materials and Metallurgical Processing”, pp. 337-349. the experimental results which are shown in the scatter plots.

Weld bead width (w) and height of reinforcement (h) increase [13] Russell G. Keanini, (1993), Simuataion of weld pool with increase in wire feed rate. Weld bead width and height of flow and capillary interface shapes associated with the plasma reinforcement decrease with the increase in welding speed. arc welding process, Finite Elemets in Analysis and Design Weld bead width and height of reinforcement increase with 15:pp 83-92. increase in nozzle-to-plate distance. Height of reinforcement increases with the increase in the wire feed rate for all values of welding speed. The microstructure shows the depth of weld

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