Cover
Vol. 17 No. 2 (2017)

Published: September 30, 2017

Pages: 1-8

Original Article

Effect of Retained Austenite on the Micro-structure and Mechanical Properties of AI-SI4340 High Strength Low Alloy Steel (HSLA steel) Using Magnetic Saturation Measurement and X-Ray Diffraction methods

Nagham. M Abdulkareem 1 Murtadha A. Jabbar 1
1 Department of Mechanical Engineering University of Basra Collage of Engineering
History
  • Received: June 30, 2017
  • Available Online: September 30, 2017
DOI

https://doi.org/10.33971/bjes.17.2.1

Abstract

Retained Austenite (RA) has great deal with the me- chanical properties of high strength low alloy steel. Therefore, in this paper, Retained Austenite volume fractions have been evaluated in AISI4340 alloy steel using two well-known meth- ods, X-Ray diffraction (XRD) and magnetic measurement methods. The specimens were heat treated using different heat- ing temperature and different cooling rate (different quenching media). A comparison between the results of two methods proved that there results were approximately Identical .The results show that Retained Austenite formation increase as heating (Austenizing ) temperature increase for the same quenching media ,as well as ,it increases by increasing cooling rate . The maximum amount of Retained Austenite found as (27.2 Wt %) which recognized when the specimens heated up to 1000˚C then quenched in Water while the minimum amount of Retained Austenite found as ( 7.06 wt%) when the specimens heated up to ( 800 ˚C) then quenched in Sand. Hardness tests using Vickers and Rockwell methods were used and the results show that hardness values decreased with increasing heating temperatures and the maximum Vickers micro-hardness and Rockwell hardness numbers were equal to (121.8HRB) and ( 516.35 HV) which were detected when heating up of the speci- mens were up to 800 ˚C then quenched in water. Tensile tests show that increasing cooling rate lead to increasing in Strength due to increasing of hardness which in turn, leads to increase in yielding points and ultimate strengths. Retained austenite effects on microstructure were investigated using scanning electron microscopy (SEM) and optical microscopy and the results show that at low cooling rate the microstructure consist of bainite and/or martensite phase with small amount of re- tained austenite, while, increasing heating temperature and cooling rate results in microstructure consist of martensite and retained austenite phases.

Keywords

References

  1. Nathan Pappas, "Calculating Retained Austenite in Steel Post Magnetic Processing Using X-Ray Diffraction", B.S. Undergraduate Mathematics Exchange, Vol. 4, No. 1, PP. 8-14, 2006.
  2. Robert W. Cahn and Peter Haasen, "Physical Metallur- gy", Fourth edition, Vol.3, Elsevier Science B.V, PP. 681-746, 1996 .
  3. L. Zhao , N.H. van Dijk , E. Bruck , J. Sietsma and S. van der Zwaag, "Magnetic and X-ray diffraction meas- urements for the determination of retained austenite in TRIP steels" , Materials Science and Engineering A313 , PP.145–152, 2001.
  4. N.H. van Dijk , A.M. Butt ,L. Zhao , J. Sietsma , S.E. Offerman ,J.P. Wright and S. van der Zwaag , " Ther- mal stability of retained austenite in TRIP steels stud- ied by synchrotron X-ray diffraction during cooling" Acta Materialia , PP.5439–5447, 2005.
  5. Felipe Lucas Sicupira, Maria Jos´e R. Sandim, Hugo R.Z. Sandim, Dagoberto Brand˜ao Santos and Reny Angela Renzetti , "Quantification of retained austenite by X-ray diffraction and saturation magnetization in a Supermartensitic stainless steel", Elsevier Inc. , Vol- ume 115 , PP. 90-96 , 2016 .
  6. Ryu H.B., Speer J.G. and Wise J.P. , " Effect of the thermo mechanical processing on the retained aus- tenite content in a Si – Mn transformation – induced plasticity steel ", A Metallurgical and Materials Trans- actions, Vol. 33, PP. 2811 – 2816, 2002.
  7. ASTM , "standard test methods, practices, terminology for chemical analysis of steel products" , Annual Book of ASTM standard A751 – 01, ASTM Interna- tional , 2001.
  8. ASTM, "standard test methods and definition for me- chanical testing of steel products" , Annual Book of ASTM standard A370 – 02, ASTM International , 2002.
  9. ASTM , "Standard practice for x – ray determination of retained austenite is steel with near random crystallo- graphic orientation" , Annual Book of ASTM stand- ard E975 – 3, ASTM International , 2007.
  10. ASM Hand book , "Heat treating" , American Society for Metals , Vol.4, Metals Park, Ohio, USA, 2002.
  11. J. D. Makinson, W. N. Weins, and R. J. De Angelis, "The Substructure of Austenite And Martensite Through a Carburized Surface," Ad- vances in X-Ray Analysis, 34, PP. 483-491,1990.
  12. Joseph Lucas, "Re magnetization of Magnetos", Lucas Quality Equipment, section D-6, Vol.2, PP.1-8, 1952.
  13. Askeland D.R. and Phule P.P. , "The science and en- gineering of materials" , fourth Edition , Brooks/Cole, a division of Thomson learning , 2003.
  14. ASTM , "standard test methods, practices, terminology for chemical analysis of steel products" , Annual Book of ASTM standard A751 – 01, ASTM International , 2001.
  15. ASTM , " Standard Test Methods for Rockwell Hard- ness of Metallic Materials" , Annual Book of ASTM standard E18-17, ASTM International , 2015.
  16. ASTM , " Standard Test Methods for Vickers Hardness and Knoop Hardness of Metallic Materials" , Annual Book of ASTM standard E92-82, ASTM International , 2003 .
  17. ASTM , " Standard Guide for Preparation of Metallo- graphic Specimens" , Annual Book of ASTM standard E3-11, ASTM International , 2011.
  18. ASTM , " Standard Practice for Microetching Metals and Alloys" , Annual Book of ASTM standard E407- 07, ASTM International , 2015.
  19. AJUS , C. TAVARES , S.S.M. SILVA , M.R. CORTE and R.R.A., " Magnetic properties and retained austenite quantification in SAE 4340 steel", Revista Matéria, v. 14, n. 3, PP. 993 – 999, 2009.
  20. Murtadha A. Jabbar, " Effect of Retained Austenite on Tensile Strength and Hardness of Low Alloy Steels Using Artificial Neural Networks", University of Bas- ra, Department of Mechanical Engineering , PP. 1-75 , 2010.
  21. Z.Samadi Shahreza1, G. Dini and A. Taherizadeh, " Improving the Microstructure, Mechanical and Mag- netic Properties of AISI 4340 Steel Using the Heat Treatment Process " , International Journal of ISSI, Vol.10 ,No.2, PP. 18-22. 2013.
  22. William D. Callister and David G. Rethwisch , " Mate- rials Science and engineering an introduction", seventh Edition , John Wily and Sons Inc. , PP. 252-303.
  23. Online Metal.com, "4340 - alloy round bar air melt".
  24. Yang-Yu Su , Liu-Ho Chiu , Tao-Liang Chuang , Chien-Lung Huang , Cheng-Yen Wu and Kuan-Chueh Liao , "Retained austenite amount determination com- parison in JIS SKD11 steel using quantitative Metal- lography and X-ray diffraction methods ", Advanced Materials Research , Vols. 482-484 , PP. 1165-1168 , 2012.