FEATURE ADVANCED MATERIALS & PROCESSES | MAY/JUJNE 2024 44 many plants begin at 95°C for oil quenching, or at ~175°C for salt quenching, and progressively increase the temperature until the best combination of hardness and distortion is obtained. Time in the martempering bath depends on section thickness and on the type, temperature, and degree of agitation of the quenching medium. Because the object of martempering is to develop a martensitic structure with low thermal and transformation stresses, there is no need to hold the steel in the martempering bath for extended periods. Excessive holding lowers final hardness because it permits transformation to products other than martensite. In addition, stabilization may occur in medium-alloy steels that are held for extended periods at the martempering temperature. ~HTPro For more information: Lauralice C.F. Canale, associate professor, Universidade de Sao Paulo, lfcanale@sc.usp.br. References 1. H.E. Boyer and P.R. Cary, Chap. 4, Molten Quenching Methods: Martempering and Austempering, Quenching and Control of Distortion, ASM International, p 71–88, 1988. 2. P. Vamsi Krishna, et al., Effect of Austempering and Martempering on the Properties of AISI 52100 Steel, ISRN Tribol., Vol 2013, 2013, doi.org/10.5402/2013/515484. 3. S. Skidmore, Salt Bath Quenching—A Review, Heat Treat. Met., Vol 2, p 34-38, 1986. 4. D.H. Herring, Secrets of Effective Hot Oil Quenching, Ind. Heat., April 4, 2006. 5. J.R. Keough, Austempered Steel, ASM Handbook, Vol 4A, Steel Heat Treating Fundamentals and Processes, p 352–361, 2013, doi.org/10.31399/asm.hb.v04a.a0005810. 6. H. Webster and W.J. Laird, Martempering of Steel, ASM Handbook, Vol 4, Heat Treating, ASM International, p 137–151, 1991. thermcraftinc.com • (336) 784-4800 Industrial& Laboratory Furnaces, Ovens& Heaters • Batch or Continuous Processing • Durable Construction • Standard or Fully Customizable • Up to 1800ºC, 3272ºF • Single or Multi-Zone • PLC Controls Available • Made in the USA Since 1971 thermcraftinc.com • (336) 784-4800 7 HeatTreatingDirectory.com Simplify Your Search for Vendors Find the right solutions for your business. Search for products, research companies, connect with suppliers, and make confident purchasing decisions all in one place.
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