Effect of Heat Treatment and Cryogenics On
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Eastern-European Journal of Enterprise Technologies ISSN 1729-3774 2/12 ( 92 ) 2018 UDC 664.6:664.95 Описано результати досліджень мож- DOI: 10.15587/1729-4061.2018.129013 ливостей підвищення механічних власти- востей чавунів з кулястим графітом марки FCD-50 шляхом комбінованої термічної оброб- EFFECT OF HEAT ки. Запропоновано схему багатоступінчастої термічної обробки, характерною особливістю TREATMENT AND якої є операція охолодження у рідкому азоті. Використання такої схеми дозволяє отрима- CRYOGENICS ON ти підвищені характеристики твердості HRC. Дослідженням мікроструктури чавунів, обро- HARDNESS OF блених за такою схемою, доведена ефектив- ність кріогенного етапу термічної обробки та DUCTILE CAST IRON визначено її раціональні режими. Ключові слова: FCD-50, чавун з кулястим MICROSTRUCTURE графітом, термічна обробка, криогенна оброб- ка, твердість, мікроструктура (FCD-50) Suriansyah Sabarudin Master Описаны результаты исследований воз- Department of Mechanical Engineering можностей повышения механических свойств University of Widyagama Malang чугунов с шаровидным графитом марки FCD- Jalan. Borobudur., 35, Malang, Indonesia, 65128 50 путем комбинированной термической обра- Е-mail: [email protected] ботки. Предложена схема многоступенчатой Pratikto термической обработки, характерной особен- Doctorate, Professor* ностью которой является операция охлаж- Е-mail: [email protected] дения в жидком азоте. Использование такой Agus Suprapto схемы позволяет получить повышенные харак- Doctorate, Professor теристики твердости HRC. Исследованием Department of Mechanical Engineering микроструктуры чугунов, обработанных по University of Merdeka Malang такой схеме, доказана эффективность крио- Jalan. Terusan Raya Dieng, 62-64, Malang, Indonesia, 65146 генного этапа термической обработки и опре- Е-mail: [email protected] делены ее рациональные режимы. Ключевые слова: FCD-50, чугун с шаровид- Yudy Surya Irawan ным графитом, термическая обработка, кри- Doctorate* огенная обработка, твердость, микрострук- Е-mail: [email protected] тура *Department of Mechanical Engineering University of Brawijaya Malang Jalan. Mayjend Haryono, 167, Malang, Indonesia, 65145 1. Introduction 2. Literature review and problem statement Ductile cast iron, also known as nodular cast iron, sphe- This study is supported by several previous studies, includ- roidal graphite iron (S.G. iron) and spherulitic iron, has the ing a two-step austempering process, the process is carried out best mechanical properties when compared to other types of by heating at a temperature of 900 °C, holding for 60 minutes. cast iron. When compared to steel, however, the mechanical All specimens were cooled at 260 °C for 10 minutes. In the properties of cast iron fall short. For both motor vehicles and subsequent process, the specimens were reheated at different production machinery, component–component machines temperatures of 280 °C, 310 °C and 340 °C held respectively have been developed as indicated by field data. The com- for 60 minutes and 120 minutes. The highest yield for me- ponents of these machines that contain cast iron graphite chanical properties (toughness) is achieved when heating at round include gears, shafts, piston rings, and cylinder liners a temperature of 280 °C, while the highest tensile strength is and heads. Similarly, when agricultural lands and planta- obtained at a heating temperature of 340 °C with each holding tions are transformed into residential areas and multi-story for 60 minutes [1]. The nodular cast iron (NCI) was investi- buildings, the construction requires a significant amount of gated according to its mechanical properties. The result of aus- reinforcing steel, which is the predominant role of steel in tempering two-step heat treatment on mechanical properties the construction of buildings and housing. Improved ductile obtained a higher value than one step. The optimum value of cast iron can be used as a steel partner to meet the need for mechanical properties occurred at tensile strength and hard- reinforcing steel. ness at 340 °C austempered temperature with a holding time 20 Suriansyah Sabarudin, Pratikto, Agus Suprapto, Yudy Surya Irawan, 2018 Materials Science of 60 min and followed by a lower austempered temperature, 4. Materials and Methods 310 °C, and 280 °C. The impact toughness value decreased at 340 °C austempered temperature with a 60-minute holding The aim of this study was to improve the mechanical time [2]. The purpose of this study was to investigate the effect properties of ductile cast iron (FCD-50). The test equipment of cryogenic, martemper and temperament cooling and cryo- was prepared in several laboratories and included 2 electric genic cooling directly on hardness and cast iron microorgan- kitchen units, 2 liquid nitrogen containers and some sup- isms (FC-20). The results of this trial show that the indirect porting equipment. To determine whether the mechanical test of FC-20 (As-cast) shows a decrease in hardness while the properties of the ductile cast iron specimens increased after FC-20 (AS-cast) test results directly cool the liquid nitrogen the ACTDI process, the researchers measured hardness with increasing hardness. The mechanical properties of As- and observed the microstructures of the samples [6]. The Cast, its hardness is 86.65 HRB on the indirect treatment of ACTDI process resulted in increased hardness and micro- decreased hardness. Indirect hardness treatment increased structure changes in ductile cast iron (FCD-50) as listed in from 123.6 HRB to 126.6 HRB. So if calculated carefully, the hardness data table (Table 1). there is an increase >40 % for hardness [3]. The research with Cast iron is included in the ferrous metals, which are Cryogenic and Temperature treatment was done on carbide used widely in the automotive industry. The properties of chisel at AL-6061. The purpose of this study is to determine cast iron include better vibration dampers of steel, machin- the wear and tear that occurs both on cutting chisel of As-Cast ing capability, wear resistance and hardness [7]. In addition, and cut chisel of modifications. The results of this research are: during the formation process cast iron has advantages in the deeper the cutting result, the worsening edge of cutting terms of depreciation. Shrinkage for cast iron is 0.5–2.0 %, chisel is getting bigger, the result of the cutting tool (carbide whereas for steel it is 3.0–5.0 %. In addition, cast iron is chisel) from the Cryogenic treatment results, better in wear much less expensive than steel. Until now cast iron can be resistance. Similarly, carbide chains with cryogenic + temper classified into five. treatment are also better resulted in wear resistance compared This type of cast iron is produced during the casting pro- to As-Cast carbide chisels, the buildup of grains of AL-6061 is cess with rapid cooling, and its microstructure is composed thinner than that of As-Cast carbide [4]. In this study, the steel primarily of cementite (Fe3C). It is, therefore, very fragile was processed by an austempering method with a temperature and cannot be applied except as raw material for malleable of 325 °C and produced specimen with high toughness as for cast iron with a small load. its microstructure is bainitic perlite, this research is assisted This type of cast iron is produced by casting with metal by observation of crystallography, TEM, and SEM [5]. A study melting using the cupula furnace, and its characteristics of Austen ductile iron (ADI) was carried out, in which the are better than those of white cast iron because the micro- microstructure was studied. In austempered temperatures, the structure is different. The microstructure contains graphite , results of this study are as-cast microstructure changes that perlite and perrit e. One characteristic of the microstructure result in improved crack propagation performance due to the in cast iron that can weaken it and reduce tensile strength reduction of eutectic carbide and the relatively high amount is the flake shape of the graphite, which makes cast iron of austenite due to heat treatment [6]. The specimens studied brittle. Despite these weaknesses, however, cast iron of this were Austempered Austen iron with the austempering process type still has advantages, including ( 1) a high damping ca- at 450 °C, from which the coating process proceeded and pacity (damping vibration) , (2) the capacity to enter into the produced tensile properties and increased fatigue properties cavity in a complicated form at the time of casting, (3) the [7]. This study resulted in austempering time on optimum relatively lower price , (4) ease of machining, (5) compressive mechanical properties of austempered materials at 315 and strength (which is higher than its tensile strength), (6) abil- 350 °C of 240 and 180 min. Further results are austempering ity to withstand heat up to 4,000 °C, (7) better resistance at 350 °C, compared with austempering at 315 °C, obtaining to corrosion compared to ordinary steel constructions, ( 8) higher ductility and less toughness and strength and hardness. low shrinkage (0.5–2 % ), and (9) ability to withstand wear The best mechanical properties are at the bottom of block (friction), because graphite can serve as a lubricant . Y [8]. In this study, we discussed the influence of chemical This type of cast iron has better quality than grey cast elements on heat treatment on the Austempered Ductile Iron iron. This type of cast iron is produced by the heat treatment (ADI)