Fracture Assessment of Martempered and Quenched and Tempered Alloy Steel
The failure analyst is often put in the position to answer whether a fracture is “abnormal” for a material or whether a material was properly heat treated. In particular, the authors have been consulted regarding low alloy steels on two specific points.
The first common question is whether a steel has been martempered per a specification, rather than quenched and tempered (Q&T), and whether the heat treatment contributed to a fracture. Martempering (sometimes termed marquenching) is a commercially available heat treatment process that quenches the material to an intermediate temperature just above the martensite start temperature, Ms, and then air cools through the martensitic transformation range to room temperature [1, 2, 3, 4]. It is important to air cool through the transformation range since rapid cooling through this range is predicted to produce residual stress patterns similar to those produced by a direct quench and negate any advantages of the process . Modified...
KeywordsIntergranular Fracture Austempering Transverse Crack High Carbon Steel Microvoid Coalescence
- 1.Krauss, G.: Steels: Heat Treatment and Processing Principles, pp. 266–268. ASM International, Materials Park, OH (1990)Google Scholar
- 2.Smith, W.F.: Structure and Properties of Engineering Alloys, 2nd edn., pp. 78–79. McGraw-Hill, New York (1993)Google Scholar
- 3.Chandler, H. (ed.): Heat Treater’s Guide: Practices and Procedures for Irons and Steels, pp. 101–104. ASM International, Materials Park, OH (1995)Google Scholar
- 4.Weber, H., Laird, W.J.: Martempering of steel. In: ASM Metals Handbook, pp. 137–138. ASM International, Materials Park, OH (1991)Google Scholar
- 6.Shepherd, B.F.: Martempering steel limitations of hardness penetration. Prod. Eng. 16(8), 515–517 (1945)Google Scholar
- 7.Shepherd, B.F.: Mechanical and metallurgical advantages of martempering steel. Prod. Eng. 16(7), 438–441 (1945)Google Scholar
- 8.Keough, J.R., Laird, W.J., Godding, A.D.: Austempering of steel. In: ASM Metals Handbook, vol. 4, Heat Treating, p. 152. ASM International, Materials Park, OH (1991)Google Scholar
- 9.Miller, B.A.: Overload failures. In: ASM Metals Handbook, vol. 11, Failure Analysis and Prevention, p. 692. ASM International, Materials Park, OH (2002)Google Scholar
- 11.Davis, J.R. (ed.): ASM Metals Handbook, vol. 12, Fractography, pp. 291–350. ASM International, Materials Park, OH (1987)Google Scholar
- 12.Chandler, H. (ed.): Heat Treater’s Guide: Practices and Procedures for Irons and Steels, pp. 319–327. ASM International, Materials Park, OH (1995)Google Scholar