Obtaining Excellent Mechanical Properties in an Ultrahigh-Strength Stainless Bearing Steel via Solution Treatment

Abstract

A novel versatile ultrahigh-strength stainless bearing steel was prepared by first solution treating the steel at temperatures between 1000 °C and 1100 °C for 1 h, followed by performing cryogenic treatment at −73 °C for 2 h, and tempering at 500 °C for 2 h, with the cryogenic and tempering treatments being repeated twice. The microstructures were characterized using multiscale techniques, and the mechanical properties were investigated using tensile testing, as well as via Rockwell hardness and impact toughness measurements. Tensile strength was found to be independent of solution temperature, with a value of about 1800 MPa. In contrast, yield strength decreased from 1530 MPa to 1033 MPa with increasing solution temperature, while tensile elongation increased from 15.3% to 20.5%. This resulted in an excellent combined product of tensile strength and elongation for steels initially treated at 1080 °C and 1100 °C, with values of 33.9 GPa·% and 37.0 GPa·%, respectively. Furthermore, the steels showed excellent impact toughness, increasing from 37.0 J to 86.2 J with increasing solution temperature. The microstructural and mechanical investigations reveal that the excellent mechanical properties and impact toughness are related to three factors, namely (i) a transformation-induced plasticity effect, mainly attributed to a high volume fraction of retained austenite, (ii) a high strengthening capacity arising from a high dislocation density, and (iii) a synergistic effect due to cobalt additions and the nanoprecipitation of M2C and M6C carbides.

Optimizing Stainless Steel Bearings: Enhancement of Stainless Steel Bearing Fatigue Life by Low-Temperature Forming

“…Extensive research has been done in the field of additive manufacturing, where one approach was to add a stainless steel layer to a base of less valuable steel, which leads to a hybrid steel-steel component. Also, the effects of treating stainless steel with a solution in order to make it more durable and therefore more suitable for bearing applications have been investigated [21].…”

Effect of Cold Rolling and Cryogenic Treatment on the Microstructure and Mechanical Properties of Fe–32Ni Alloy

“…The test results on W6 high-speed steel after cryogenic treatment at −150 • C for 12 h have shown that the formation of fine carbides, uniformly distributed in the steel, reduces the dislocation stress and ultimately affects the macroscopic residual stress [20]. In addition, cryogenic treatment is widely applied to stainless steels [21], magnesium alloys [22], titanium alloys [23] and others. Therefore, it is necessary to study the influence of rolling deformation and cryogenic treatment on microstructure and properties.…”