DOCSLIB.ORG

Metallographic Study of Phase Changes in Heat Treated Ductile Iron

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Metallographic Study of Phase Changes in Heat Treated Ductile Iron Scholars' Mine Masters Theses Student Theses and Dissertations 1970 Metallographic study of phase changes in heat treated ductile iron Mahendra Vadilal Desai Follow this and additional works at: https://scholarsmine.mst.edu/masters_theses Part of the Metallurgy Commons Department: Recommended Citation Desai, Mahendra Vadilal, "Metallographic study of phase changes in heat treated ductile iron" (1970). Masters Theses. 7073. https://scholarsmine.mst.edu/masters_theses/7073 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. METALLOGRAPHIC STUDY OF PHASE CHANGES IN HEAT TREATED DUCTILE IRON BY MAHENDRA VADILAL DESAI, 1943- A THESIS submitted to the faculty of UNIVERSITY OF MISSOURI - ROLLA in partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE IN METALLURGICAL ENGINEERING Rolla, Missouri 1970 T2321 141 pages c. I 183309 Approved by 11 ABSTRACT Continuous cast ductile iron samples were hardened. It was found that carbide dissolved in the austenite faster than graphite and that this material requires higher austen­ itizing temperatures and longer austenitizing time than steels. Tempered microstructures were affected by the prior austenitizing treatment and it appeared that the amount of carbon dissolved in the austenite determined the tempered microstructure. Several attempts to determine the austenite grain size indicated that it is not as easy to determine in ductile iron as in steels. Two techniques, heat etching and an iso­ thermal transformation method, were found to reveal prior austenite grain size. It was concluded that carbon precipitated directly as graphite from martensite in ductile iron rather than as com­ bined carbon the way it does in steels. The reason for direct precipitation of graphite from martensite was not ~o~. Repeated quenching and subsequent tempering might lead to the replacement of the primary graphite dispersion by a secondary graphite dispersion. This could alter properties but it did not appear to be a practical process because of the large number of quenching and tempering cycles required. A relationship between regular Rockwell C hardness and the matrix hardness was established which was in good 111 agreement with that in the literature. An approximate par­ tial isothermal transformation diagram is reported. tv ACKNOWLEDGEMENT The author wishes to express his gratitude to Dr. Fred Kisslinger for his guidance, advice, and assistance in the execution of this work and preparation of this thesis. The author is indebted to Wells Manufacturing Co., Skokie, Illinois, for their generosity in supplying con­ tinuous cast ductile iron for this investigation. The assistance and cooperation of the other faculty members and graduate students is gratefully acknowledged. v TA."3~ OF COt·!TEf1TS Page LIST OP PIGURES • • • • • • • • • • • vii LIST OP TABLES • • • • • • • • • • • xii I. I~JTfiODUC'l'IOJ: • • • • • • • • • • • • 1 II. LITERATURE REVIEW • • • • • • • • • • 2 III. EXPERIMENTAL PROCEDURE • • • • • • • • 6 A. '-•teria1 Studied • • • • • • • • • 8 B. Beat Treatil18 • • • • • • • • • • 9 c. Specimen Preparation • • • • • • • • 13 D. Metal1ographic Studies • • • • • • • 13 B. Hardness Testa • • • • • • • • • • 13 IV. RBSULTS AND DISCUSSIONS • • • • • • • • lS A. Barden1118 ot Ductile Iron • • • • • • 15 B. Austenite Grain Size • • • • • • • • 34 1. Gradient Quench Method • • • • • • 41 2. Vilella•s ~ethod • • • • • • • • 43 ,. OXidation Method. • • • • • • • • 4S 4. Heat EtchiM • • • • • • • • • 47 s. Isothermal Transformation • • • • • ss 6. Variation ot Tempered Microstructures • s~; c. Precipitation of carbon from r:artensite • 62 1. 'l'emperi~ ot Quenched. Ducti1e Iron • • 6) •• Samples Tempered. at 12S0°F • • • 6) b. Samples Tempered. at 1000°P • • • 69 c. Samples T•pered. at 100° and 40oop. 72 d. Diaouaaion • • • • • • • • ?2 vi Pa~e 2. Tempering of Normalized Ductile Iron • • 7 5 :3· Isothermal Transformation of Ductile Iron 7R a. Isothermal Transformation at 1J00°F • 80 b. Isothermal Transformation at 1200°F • A4 c. Isothermal Transformation at 11ooop • 89 d. Isothermal Tr.nsformation at l000°F • 94 e. Isothermal Transformation at 900°F • 99 4. Discussion • • • • • • • • • • 104 D. Repeated Quenching and Tempering • • • • 117 E. Relationship Between the P.ardness Readings • 121 F. Isothermal Transformation Diagram • • • • 123 v. COr.!CLUSIONS • • • • • • • • • • • • • 125 BIBLIOGRAPHY • • • • • • • • • • • • 127 VITA • • • • • • • • • • • • • • • 129 vi1 Fi~. 1 As-received sample of ductile iron which shows spheroidal primary ~raphite in a ferritic ~atrix • • • • • • • • • • • • • 11 .riP:. 2 As-received sample of d.uctile iron l:hich shows spheroidal and vermicular ~rimary ~raphi- te in a ferritic matrix. • • • • • • • 11. FiF:• 3 As-quenched hardness as a function of aue.tel"- itizin~ temperature • • • • • • • • • 18 FiP.:e 4 The hardness of martensite as a function of carbon content. • • • • • • • • • • 20 5 As-quenched hardness as a function of austen­ itizi~ time for three different auRtenitizinr." temperatures • • • • • • • • • • • 23 Fi~. 6 Sample austenitized. at 1500°F for 2 hr., water quenched. and. tempered at 1250°F for 32 hr. • 26 Fi~. 7 Sanrple austenitized. at 1600°Ii' for 2 hr., l•rater quenched and tempered at 1250°1"' for 32 ~r. • 26 Fip-. 8 Sample austeni tized at 1700°1''0 for 2 hr., water quenched. and tempered at 1250 F for 32 hr. • 27 F'ig. 9 Sample austenitized at 1800°F for 2 hr., water quenched and tempered at 1250°F for 32 hr. • 27 10 Sample austenitized at 19000F for 2 hr., water quenched and. tempered at 1250°F for 32 hr. • 2P 11 Sample austenitized at 1550°F for 4 hr., water quenched and tempered at 1250°F for 2 hr. • 30 Fil!• 12 Sample austenitized at 1550°F for 10 hr., water quenched and tempered. at 125oo.r• for 2 hr. • 30 Fip-. 13 Sample austenitized at 1.5S0°F· :for 44 hr., water quenched and te111pered at 1250°F for 2 hr. • 31 F'if". 14 Sample austenitized at 1900°F :for 15 min., ~ater quenched and tempered at 1250°F :for 2 hr. • 31 15 Sample austeni tized at 1900°F; for 60 min., water quenched and tempered at 1250°F for 2 hr. • 32 16 Sample austenitized at 1900°F for 2 hr., water quenched and tempered at 1250°P tor 2 hr. • 32 v111 Pave Pi~. 17 Grain size as a fUnction or austenitizinr. temperature for a fine-~rained ty,e steol. • 35 Fig. lA Ductile iron sample of 0.2 inch diameter that had been v,radient que~ched from 17SC0 ~ • 42 Pip-. 19 Ductile iron sample shown in Figure lP 1~ the unetched condition • • • • • • • • 44 20 AISI 1042 steel sample F.radient quenc~ed fro• 21000P • • • • • • • • • • • • • 44 Fill'. 21 Prior austenite grain s1ze as revealed b7 V11ella•s Btch 1n AI8I 1042 steel sam~le austeD1t1zed at 1900°1'·, quenched am telt'l>ered at 4ooop ~or S min. • • • • • • • · • • P1g. 22 Vycor tube containin!l: ~etter, ductile iro" and 1~t 1ron s~les for heat etch • • • so 23 Ductile 1ron sample, heat etched at 160COI'· for 2 hr., showill@' aD austenite PTain slze of M 'J.'r. No. ?-8 • • • • • • • • • • • • • 52 24 Ductile 1ron sample, heat etched at 1700°P for 2 hr., show1nr an austenite Frain s1ze of .A..:-&1!·· No. 7-8 • • • • • • • • • • • • • 52 25 Ductile 1ron sample, heat etched at 1R00°P tor 2 hr., showiq an austenite ~in size of AS'l'}' lto. 7. • • • • • • • • • • • • • 53 26 Ductile iron sample, heat etcl'ted at 19ar.· O~· ~or 2 hr., show1tur an austenite ~ra1n size of Aai't' •Jo. 6. • • • • • • • • • • • • • S3 27 Isothermal transformation sample revea11~~~t austenite ~in size at 16oooF • • • • • S7 28 Isothermal transrormat1on s~ple reveal1n~ austenite ~1n s1ze at 1700 F • • • • • S? Pitre 29 Isotheratal transtomat1on sample revealinr. austenite gra1n s1ze at 1800°P • • • • • SP 30 Isothermal transformation sample reveal1n~ austenite eratn size at 190oop • • • • • P1~. 31 Sample austen1tized at 1700°F tor 2 hr. , water quenched &1l4 tempered at 12S0°P tor 32 hr. • 61 P1~. 32 S•ple austen1t1se4 at 19000p ~or 2 hr., water quenched and t perecl at 125oop ror 32 hr. • 61 1x Par.e Fig. 33 Sample austenit1zed at 1700°F for 2 hr. and. tempered at 1250°F for S min. • • • • • 65 Fig. )4 Sample austen1t1zed at 1700°F for 2 hr. an~ tempered at 125oop for 10 min. • • • • • 6S Fig. 35 Sample austen1tized at 17ooop for 2. hr. allcl tempered. at 12SOOF • for 2 5 min. • • • • • Pig. )6 Sample austenitized at 17000F for 2 hr. e.:td tetn!)ered at 1250°F for )0 min. • • • • • 66 Fig. '37 Sample austen1tized at 1700°F for 2 hr. and. tempered at 1250°F for 2 hr. • • • • • • 67 Fig. '38 Sample austeniti~ed at 17ooop for 2 hr. and tempered at lOooop for 8 hr. • • • • • • 71 Fig. '39 Sample austen1t1zed at 1700°F for 2 hr. and tempered at lOOOOF for 20 hr. • • • • • 71 Pig. 40 Sample austenitized at 1700°P for 2 hr. and tempered at 70oop for 8 hr. • • • • • • 74 Fig. 41 Sample austenitbzed. at 17000F for 2 hr. and. tempered at 400 F for 8 hr. • • • • • • 74 Fig . 42 Sample austenitized at 1800°F for 2 hr. and air cooled. • • • • • • • • • • • • 76 Fig. 4) Sample austenitized at 18oooF for 2 hr., air cooled and tempered. at 1250°F for 5 min. • • 76 Fig. 44 Sample austenitized at 1800°F for 2 hr., air cooled and tempered at 12S00F for )0 mi~. • 77 Fig. 45 Sample austenitized at 18000F for 2 hr., air cooled and tempered. at 12S0°F for 2 hr. • • 77 Pig. 46 Sample austenitized at 1800°F for 2 hr. and tumace cooled • • • • • • • • • • 79 Fig. 47 Hard.ness variation of isothermal transformat­ ion samples at various temperatures • • • 82 Pig. 48 Sample austenitized at 1800°F for )0 min. and held at 13ooop for )0 sec. • • • • • • 8) Fig. 49 Sample austenitized at 1800°F for )0 min. and held at 1'300°F for 1 mtn. • • • • • • • as Pig. so Sample austenitized at 1800°F for 30 min.
Load more

Recommended publications
  • Wear Behavior of Austempered and Quenched and Tempered Gray Cast Irons Under Similar Hardness
    metals Article Wear Behavior of Austempered and Quenched and Tempered Gray Cast Irons under Similar Hardness 1,2 2 2 2, , Bingxu Wang , Xue Han , Gary C. Barber and Yuming Pan * y 1 Faculty of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China; [email protected] 2 Automotive Tribology Center, Department of Mechanical Engineering, School of Engineering and Computer Science, Oakland University, Rochester, MI 48309, USA; [email protected] (X.H.); [email protected] (G.C.B.) * Correspondence: [email protected] Current address: 201 N. Squirrel Rd Apt 1204, Auburn Hills, MI 48326, USA. y Received: 14 November 2019; Accepted: 4 December 2019; Published: 8 December 2019 Abstract: In this research, an austempering heat treatment was applied on gray cast iron using various austempering temperatures ranging from 232 ◦C to 371 ◦C and holding times ranging from 1 min to 120 min. The microstructure and hardness were examined using optical microscopy and a Rockwell hardness tester. Rotational ball-on-disk sliding wear tests were carried out to investigate the wear behavior of austempered gray cast iron samples and to compare with conventional quenched and tempered gray cast iron samples under equivalent hardness. For the austempered samples, it was found that acicular ferrite and carbon saturated austenite were formed in the matrix. The ferritic platelets became coarse when increasing the austempering temperature or extending the holding time. Hardness decreased due to a decreasing amount of martensite in the matrix. In wear tests, austempered gray cast iron samples showed slightly higher wear resistance than quenched and tempered samples under similar hardness while using the austempering temperatures of 232 ◦C, 260 ◦C, 288 ◦C, and 316 ◦C and distinctly better wear resistance while using the austempering temperatures of 343 ◦C and 371 ◦C.
    [Show full text]
  • ITP Metal Casting: Advanced Melting Technologies
    Advanced Melting Technologies: Energy Saving Concepts and Opportunities for the Metal Casting Industry November 2005 BCS, Incorporated 5550 Sterrett Place, Suite 306 Columbia, MD 21044 www.bcs-hq.com Advanced Melting Technologies: Energy Saving Concepts and Opportunities for the Metal Casting Industry Prepared for ITP Metal Casting by BCS, Incorporated November 2005 Acknowledgments This study was a collaborative effort by a team of researchers from University of Missouri–Rolla, Case Western Reserve University, and Carnegie Mellon University with BCS, Incorporated as the project coordinator and lead. The research findings for the nonferrous casting industry were contributed by Dr. Jack Wallace and Dr. David Schwam, while the ferrous melting technologies were addressed by Dr. Kent Peaslee and Dr. Richard Fruehan. BCS, Incorporated researched independently to provide an overview of the melting process and the U.S. metal casting industry. The final report was prepared by Robert D. Naranjo, Ji-Yea Kwon, Rajita Majumdar, and William T. Choate of BCS, Incorporated. We also gratefully acknowledge the support of the U.S. Department of Energy and Cast Metal Coalition (CMC) in conducting this study. Disclaimer This report was prepared as an account of work sponsored by an Agency of the United States Government. Neither the United States Government nor any Agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any Agency thereof.
    [Show full text]
  • 2000 Stainless Steels: an Introduction to Their Metallurgy and Corrosion
    Dairy, Food and Environmental Sanitation, Vol. 20, No. 7, Pages 506-517 Copyright© International Association for Food Protection, 6200 Aurora Ave., Suite 200W, Des Moines, IA 50322 Stainless Steels: An Introduction to Their Metallurgy and Corrosion Resistance Roger A. Covert and Arthur H. Tuthill* and why they sometimes do not. In most cases, selection of the proper stainless steel leads to satisfactory performance. COMPOSITION, NOMEN- CLATURE AND GENERAL PROPERTIES Most metals are mixtures of a primary metallic element and one or more intentionally added other ele- This article has been peer-reviewed by two professionals. ments. These mixtures of elements are called alloys. Stainless steels are alloys, as are brasses (copper + zinc), bronzes (copper + tin), the many alu- INTRODUCTION better understanding of stainless minum alloys, and many other me- Worldwide, in industry, in busi- steels, especially to the non-metal- tallic materials. In general, solid ness and in the home, metals called lurgist. metals and alloys consist of randomly stainless steels are used daily. It is Industries are concerned with oriented grains that have a well-de- important to understand what these integrity of equipment and product fined crystalline structure, or lattice, materials are and why they behave purity. To achieve these, stainless within the grains. In stainless steels, the way they do. This is especially steels are often the economical and the crystalline structures within the true because the word “stainless” is practical materials of choice for pro- grains have been given names such as itself somewhat of a misnomer; these cess equipment. However, before ferrite, austenite, martensite, or a materials can stain and can corrode intelligent decisions can be made mixture of two or more of these.
    [Show full text]
  • Role of Austenitization Temperature on Structure Homogeneity and Transformation Kinetics in Austempered Ductile Iron
    Metals and Materials International https://doi.org/10.1007/s12540-019-00245-y Role of Austenitization Temperature on Structure Homogeneity and Transformation Kinetics in Austempered Ductile Iron M. Górny1 · G. Angella2 · E. Tyrała1 · M. Kawalec1 · S. Paź1 · A. Kmita3 Received: 17 December 2018 / Accepted: 14 January 2019 © The Author(s) 2019 Abstract This paper considers the important factors of the production of high-strength ADI (Austempered Ductile Iron); namely, the austenitization stage during heat treatment. The two series of ADI with diferent initial microstructures were taken into consideration in this work. Experiments were carried out for castings with a 25-mm-walled thickness. Variable techniques (OM, SEM, dilatometry, DSC, Variable Magnetic Field, hardness, and impact strength measurements) were used for investi- gations of the infuence of austenitization time on austempering transformation kinetics and structure in austempered ductile iron. The outcome of this work indicates that the austenitizing temperature has a very signifcant impact on structure homo- geneity and the resultant mechanical properties. It has been shown that the homogeneity of the metallic matrix of the ADI microstructure strongly depends on the austenitizing temperature and the initial microstructure of the spheroidal cast irons (mainly through the number of graphite nodules). In addition, this work shows the role of the austenitization temperature on the formation of Mg–Cu precipitations in ADI. Keywords Metals · Casting · ADI · Heat treatment · Mg2Cu particles 1 Introduction light/heavy trucks, construction and mining equipment, railroad, agricultural, gears and crankshafts, and brackets, Austempered ductile iron (ADI) belongs to the spheroidal among others [5–7]. In the literature, numerous papers have graphite cast iron (SGI) family, which is subjected to heat been published on ADI: particularly, on the numerical sim- treatment; i.e., austenitization and austempering.
    [Show full text]
  • Preparation and Mechanical Behavior of Ultra-High Strength Low-Carbon Steel
    materials Article Preparation and Mechanical Behavior of Ultra-High Strength Low-Carbon Steel Zhiqing Lv 1,2,*, Lihua Qian 1, Shuai Liu 1, Le Zhan 1 and Siji Qin 1 1 Key Laboratory of Advanced Forging & Stamping Technology and Science, Ministry of Education of China Yanshan University, Qinhuangdao 066004, China; [email protected] (L.Q.); [email protected] (S.L.); [email protected] (L.Z.); [email protected] (S.Q.) 2 State Key Laboratory of Metastable Material Science and Technology, Yanshan University, Qinhuangdao 066004, China * Correspondence: [email protected] Received: 16 December 2019; Accepted: 14 January 2020; Published: 18 January 2020 Abstract: The low-carbon steel (~0.12 wt%) with complete martensite structure, obtained by quenching, was cold rolled to get the high-strength steel sheets. Then, the mechanical properties of the sheets were measured at different angles to the rolling direction, and the microstructural evolution of low-carbon martensite with cold rolling reduction was observed. The results show that the hardness and the strength gradually increase with increasing rolling reduction, while the elongation and impact toughness obviously decrease. The strength of the sheets with the same rolling reduction are different at the angles of 0◦, 45◦, and 90◦ to the rolling direction. The tensile strength (elongation) along the rolling direction is higher than that in the other two directions, but the differences between them are not obvious. When the aging was performed at a low temperature, the strength of the initial martensite and deformed martensite increased with increasing aging time during the early stages of aging, followed by a gradual decrease with further aging.
    [Show full text]
  • Structure/Property Relationships in Irons and Steels Bruce L
    Copyright © 1998 ASM International® Metals Handbook Desk Edition, Second Edition All rights reserved. J.R. Davis, Editor, p 153-173 www.asminternational.org Structure/Property Relationships in Irons and Steels Bruce L. Bramfitt, Homer Research Laboratories, Bethlehem Steel Corporation Basis of Material Selection ............................................... 153 Role of Microstructure .................................................. 155 Ferrite ............................................................. 156 Pearlite ............................................................ 158 Ferrite-Pearl ite ....................................................... 160 Bainite ............................................................ 162 Martensite .................................... ...................... 164 Austenite ........................................................... 169 Ferrite-Cementite ..................................................... 170 Ferrite-Martensite .................................................... 171 Ferrite-Austenite ..................................................... 171 Graphite ........................................................... 172 Cementite .......................................................... 172 This Section was adapted from Materials 5election and Design, Volume 20, ASM Handbook, 1997, pages 357-382. Additional information can also be found in the Sections on cast irons and steels which immediately follow in this Handbook and by consulting the index. THE PROPERTIES of irons and steels
    [Show full text]
  • Chapter 12: Phase Transformations
    Chapter 12: Phase Transformations ISSUES TO ADDRESS... • Transforming one phase into another takes time. Fe Fe C Eutectoid 3 γ transformation (cementite) (Austenite) + α C FCC (ferrite) (BCC) • How does the rate of transformation depend on time and temperature ? • Is it possible to slow down transformations so that non-equilibrium structures are formed? • Are the mechanical properties of non-equilibrium structures more desirable than equilibrium ones? AMSE 205 Spring ‘2016 Chapter 12 - 1 Phase Transformations Nucleation – nuclei (seeds) act as templates on which crystals grow – for nucleus to form rate of addition of atoms to nucleus must be faster than rate of loss – once nucleated, growth proceeds until equilibrium is attained Driving force to nucleate increases as we increase ΔT – supercooling (eutectic, eutectoid) – superheating (peritectic) Small supercooling slow nucleation rate - few nuclei - large crystals Large supercooling rapid nucleation rate - many nuclei - small crystals AMSE 205 Spring ‘2016 Chapter 12 - 2 Solidification: Nucleation Types • Homogeneous nucleation – nuclei form in the bulk of liquid metal – requires considerable supercooling (typically 80-300 °C) • Heterogeneous nucleation – much easier since stable “nucleating surface” is already present — e.g., mold wall, impurities in liquid phase – only very slight supercooling (0.1-10 °C) AMSE 205 Spring ‘2016 Chapter 12 - 3 Homogeneous Nucleation & Energy Effects Surface Free Energy- destabilizes the nuclei (it takes energy to make an interface) γ = surface tension ΔGT = Total Free Energy = ΔGS + ΔGV Volume (Bulk) Free Energy – stabilizes the nuclei (releases energy) r* = critical nucleus: for r < r* nuclei shrink; for r > r* nuclei grow (to reduce energy) Adapted from Fig.12.2(b), Callister & Rethwisch 9e.
    [Show full text]
  • Comparison of Wear Performance of Austempered and Quench-Tempered Gray Cast Irons Enhanced by Laser Hardening Treatment
    applied sciences Article Comparison of Wear Performance of Austempered and Quench-Tempered Gray Cast Irons Enhanced by Laser Hardening Treatment Bingxu Wang 1,2,*, Gary C. Barber 2, Rui Wang 2,3 and Yuming Pan 2 1 Faculty of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, #928 No.2 Street, High Education Zone, Hangzhou 310018, China 2 Department of Mechanical Engineering, School of Engineering and Computer Science, Oakland University, Rochester, MI 48309, USA; [email protected] (G.C.B.); [email protected] (R.W.); [email protected] (Y.P.) 3 College of Modern Science and Technology, China Jiliang University, Hangzhou 310018, China * Correspondence: [email protected] Received: 30 March 2020; Accepted: 26 April 2020; Published: 27 April 2020 Abstract: The current research studied the effects of laser surface hardening treatment on the phase transformation and wear properties of gray cast irons heat treated by austempering or quench-tempering, respectively. Three austempering temperatures of 232 ◦C, 288 ◦C, and 343 ◦C with a constant holding duration of 120 min and three tempering temperatures of 316 ◦C, 399 ◦C, and 482 ◦C with a constant holding duration of 60 min were utilized to prepare austempered and quench-tempered gray cast iron specimens with equivalent macro-hardness values. A ball-on-flat reciprocating wear test configuration was used to investigate the wear resistance of austempered and quench-tempered gray cast iron specimens before and after applying laser surface-hardening treatment. The phase transformation, hardness, mass loss, and worn surfaces were evaluated. There were four zones in the matrix of the laser-hardened austempered gray cast iron.
    [Show full text]
  • Cast Irons$ KB Rundman, Michigan Technological University, Houghton, MI, USA F Iacoviello, Università Di Cassino E Del Lazio Meridionale, DICEM, Cassino (FR), Italy
    Cast Irons$ KB Rundman, Michigan Technological University, Houghton, MI, USA F Iacoviello, Università di Cassino e del Lazio Meridionale, DICEM, Cassino (FR), Italy r 2016 Elsevier Inc. All rights reserved. 1 Metallurgy of Cast Iron 1 2 Solidification of a Hypoeutectic Gray Iron Alloy With CE¼4.0 3 3 Matrix Microstructures in Graphitic Cast Irons – Cooling Below the Eutectic 3 4 Microstructure and Mechanical Properties of Gray Cast Iron 4 5 Effect of Carbon Equivalent 5 6 Effect of Matrix Microstructure 5 7 Effect of Alloying Elements 5 8 Classes of Gray Cast Irons and Brinell Hardness 5 9 Ductile Cast Iron 5 10 Production of Ductile Iron 6 11 Solidification and Microstructures of Hypereutectic Ductile Cast Irons 6 12 Mechanical Properties of Ductile Cast Iron 7 13 As-cast and Quenched and Tempered Grades of Ductile Iron 8 14 Malleable Cast Iron, Processing, Microstructure, and Mechanical Properties 8 15 Compacted Graphite Iron 9 16 Austempered Ductile Cast Iron 9 17 The Metastable Phase Diagram and Stabilized Austenite 9 18 Control of Mechanical Properties of ADI 10 19 Conclusion 10 References 11 Further Reading 11 Cast irons have played an important role in the development of the human species. They have been produced in various compositions for thousands of years. Most often they have been used in the as-cast form to satisfy structural and shape requirements. The mechanical and physical properties of cast irons have been enhanced through understanding of the funda- mental relationships between microstructure (phases, microconstituents, and the distribution of those constituents) and the process variables of iron composition, heat treatment, and the introduction of significant additives in molten metal processing.
    [Show full text]
  • The Effect of Tempering on the Microstructure and Mechanical
    applied sciences Article The Effect of Tempering on the Microstructure and Mechanical Properties of a Novel 0.4C Press-Hardening Steel Oskari Haiko 1,* , Antti Kaijalainen 1 , Sakari Pallaspuro 1 , Jaakko Hannula 1, David Porter 1, Tommi Liimatainen 2 and Jukka Kömi 1 1 Materials and Mechanical Engineering, Centre for Advanced Steels Research, University of Oulu, 90014 Oulu, Finland; antti.kaijalainen@oulu.fi (A.K.); sakari.pallaspuro@oulu.fi (S.P.); jaakko.hannula@oulu.fi (J.H.); david.porter@oulu.fi (D.P.); jukka.komi@oulu.fi (J.K.) 2 Raahe Works, SSAB Europe, 92100 Raahe, Finland; [email protected] * Correspondence: oskari.haiko@oulu.fi Received: 12 September 2019; Accepted: 4 October 2019; Published: 10 October 2019 Featured Application: Potential wear-resistant steel for harsh environments in agricultural sector, i.e., chisel ploughs and disc harrows. Abstract: In this paper, the effects of different tempering temperatures on a recently developed ultrahigh-strength steel with 0.4 wt.% carbon content were studied. The steel is designed to be used in press-hardening for different wear applications, which require high surface hardness (650 HV/58 HRC). Hot-rolled steel sheet from a hot strip mill was austenitized, water quenched and subjected to 2-h tempering at different temperatures ranging from 150 ◦C to 400 ◦C. Mechanical properties, microstructure, dislocation densities, and fracture surfaces of the steels were characterized. Tensile strength greater than 2200 MPa and hardness above 650 HV/58 HRC were measured for the as-quenched variant. Tempering decreased the tensile strength and hardness, but yield strength increased with low-temperature tempering (150 ◦C and 200 ◦C).
    [Show full text]
  • The Role of Alloying Elements on the Fabricability of Austenitic Stainless Steel
    The Role of Alloying Elements on the Fabricability of Austenitic Stainless Steel John C. Tverberg, P.E. Metals and Materials Consulting Engineers Mukwonago, Wisconsin How many times have fabrication problems developed when a new coil or a new heat of steel is put in production? The problems can be tearing, cracking, scratching, poorer weld penetration, poor electropolished surface or a host of other problems. The usual procedure to determine the source of the problem is a hardness test, tensile test, and metallographic cross section and to review the mill test reports. Sometimes the source of the problem is spotted, but most often nothing out of the ordinary is found. In these cases the problem lies in the composition of the steel even when the alloy is within the specified composition of the steel. Alloy Design Austenitic stainless steels are designed to give corrosion resistance in many environments, resistance to hydrogen and 885º F (475º C) embrittlement, good strength, good ductility and low hardness. In its simplest form stainless steel is iron with 12% minimum chromium. This is what makes stainless steel rust resistant and allows the passive film to develop. Stainless steel exists in three metallurgical conditions depending on composition and heat treatment: ferritic, martensitic and austenitic. These names refer to the crystallographic structure: ferrite is body-centered cubic, austenite is face-centered cubic and martensite is a distorted tetragonal which is the distorted face-centered cubic structure being changed into a body-centered structure. The characteristics of these structures are tabulated in Table I and are illustrated in Figure 1.
    [Show full text]
  • Effect of Melting Process and Aluminium Content on the Microstructure and Mechanical Properties of Fe–Al Alloys
    ISIJ International, Vol. 50 (2010), No. 10, pp. 1483–1487 Effect of Melting Process and Aluminium Content on the Microstructure and Mechanical Properties of Fe–Al Alloys Shivkumar KHAPLE, R. G. BALIGIDAD, M. SANKAR and V. V. Satya PRASAD Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad, 500058 India. E-mail: [email protected] (Received on January 4, 2010; accepted on July 1, 2010) This paper presents the effect of air induction melting with flux cover (AIMFC) versus vacuum induction melting (VIM) on the recovery of alloying element, reduction of impurities, workability and mechanical prop- erties of Fe–(7–16mass%)Al alloys. Three Fe–Al alloy ingots containing 7, 9 and 16 mass% Al were prepared by both AIMFC and VIM. All these ingots were hot-forged and hot-rolled at 1 373 K and were further charac- terized with respect to chemical composition, microstructure and mechanical properties. The recovery of aluminium as well as reduction of oxygen during both AIMFC and VIM is excellent. AIMFC ingots exhibit low level of sulphur and high concentration of hydrogen as compared to VIM ingots. VIM ingots of all the three alloys were successfully hot worked. However, AIMFC ingots of only those Fe–Al alloys containing lower concentration of aluminium could be hot worked. The tensile properties of hot-rolled Fe–7mass%Al alloy produced by AIMFC and VIM are comparable. The present study clearly demonstrates that it is feasible to produce sound ingots of low carbon Fe–7mass%Al alloy by AIMFC process with properties comparable to the alloy produced by VIM. KEY WORDS: air inducting melting with flux cover; vacuum induction melting; Fe–Al alloy; microstructure; mechanical properties.
    [Show full text]