Influence of soaking time in deep cryogenic treatment on the microstructure and mechanical properties of low-alloy medium-carbon HY-TUF steel

Abstract

The influence of soaking time in deep cryogenic treatment on the tensile and impact properties of low-alloy medium-carbon HY-TUF steel was investigated in this study. Microstructural studies based on phase distribution mapping by electron backscatter diffraction show that the deep cryogenic process causes a decrease in the content of retained austenite and an increase in the volume fraction of η-carbide with increasing soaking time up to 48 h. The decrease in the content of retained austenite from ~1.23vol% to 0.48vol% suggests an isothermal martensitic transformation at 77 K. The η-type precipitates formed in deep cryogenic-treated martensite over 48 h have the Hirotsu and Nagakura orientation relation with the martensitic matrix. Furthermore, a high coherency between η-carbide and the martensitic matrix is observed by high-resolution transmission electron microscopy. The variations in macrohardness, yield strength, ultimate tensile strength, and ductility with soaking time in the deep cryogenic process show a peak/plateau trend.

Keywords

low alloy steel / medium carbon steel / cryogenic treatment / microstructure / mechanical properties / fractography

References

[1] Baldissera P., Delprete C. Deep cryogenic treatment: a bibliographic review. Open Mech. Eng. J., 2008, 2, 1.

[2] Molinari A., Pellizzari M., Gialanella S., Straffelini G., Stiasny K.H. Effect of deep cryogenic treatment on the mechanical properties of tool steels. J. Mater. Process. Technol., 2001, 118(1-3): 350.

[3] Collins D.N. Deep cryogenic treatment of tool steels: a review. Heat Treat. Met., 1996, 23(2): 40.

[4] Koneshlou M., Asl K.M., Khomamizadeh F. Effect of cryogenic treatment on microstructure, mechanical and wear behaviors of AISI H13 hot work tool steel. Cryogenics, 2011, 51(1): 55.

[5] Firouzdor V., Nejati E., Khomamizadeh F. Effect of deep cryogenic treatment on wear resistance and tool life of M2 HSS drill. J. Mater. Process. Technol., 2008, 206(1-3): 467.

[6] Lal D.M., Renganarayanan S., Kalanidhi A. Cryogenic treatment to augment wear resistance of tool and die steels. Cryogenics, 2001, 41(3): 149.

[7] Tyshchenko A.I., Theisen W., Oppenkowski A., Siebert S., Razumov O.N., Skoblik A.P., Sirosh V.A., Petrov Yu.N., Gavriljuk V.G. Low-temperature martensitic transformation and deep cryogenic treatment of a tool steel. Mater. Sci. Eng. A, 2010, 527(26): 7027.

[8] Zhirafar S., Rezaeian A., Pugh M. Effect of cryogenic treatment on the mechanical properties of 4340 steel. J. Mater. Process. Technol., 2007, 186(1-3): 298.

[9] Senthilkumar D., Rajendran I., Pellizzari M., Siiriainen J. Influence of shallow and deep cryogenic treatment on the residual state of stress of 4140 steel. J. Mater. Process. Technol., 2011, 211(3): 396.

[10] Klopp W. Aerospace Structural Metals Handbook, 1992 18.

[11] Zare A., Mansouri H., Hosseini S.R. Effect of deep cryogenic treatment on the microstructure and mechanical properties of HY-TUF steel. Metallogr. Microstruct. Anal, 2015, 4(3): 169.

[12] ASTM Standards, E8-04: Standard Test Methods for Tension Testing of Metallic Materials, American Society for Testing and Materials, West Conshohocken, Pennsylvania, USA, 2004.

[13] Zare A., Ekrami A. Influence of martensite volume fraction on tensile properties of triple phase ferrite–bainite–martensite steels. Mater. Sci. Eng. A, 2011, 530, 440.

[14] ASTM Standards, E23-09: Standard Test Method for Notched Bar Impact Testing of Metallic Materials, American Society for Testing and Materials, West Conshohocken, Pennsylvania, USA, 2009.

[15] Gavriljuk V.G., Theisen W., Sirosh V.V., Polshin E.V., Kortmann A., Mogilny G.S., Petrov Yu. N., Tarusin Ye. V. Low-temperature martensitic transformation in tool steels in relation to their deep cryogenic treatment. Acta Mater., 2013, 61(5): 1705.

[16] Vucko F., Bosch C., Delafosse D. Experimental investigations of internal and effective stresses during fatigue loading of high-strength steel. Mater. Sci. Eng. A, 2014, 597, 381.

[17] Sanctis M., Lovicu G.F. Property models for mixed microstructures in high strength microalloyed steels. Sixth Italian Conference Processing Engineering (ICheap-6), 2000 8.

[18] Thomson R., Miller M. Carbide precipitation in martensite during the early stages of tempering Cr-and Mo-containing low alloy steels. Acta Mater., 1998, 46(6): 2203.