Developing bearing steels combining hydrogen resistance and improved hardness

作者：Szost B A; Vegter R H; Rivera Diaz del Castillo P E J^*

来源：Materials & Design, 2013, 43: 499-506.

DOI：10.1016/j.matdes.2012.07.030

• Hydrogen embrittlement
• Precipitation
• Steel
• Nanostructured materials

Thermodynamic and kinetic computational modelling are combined to conceive a hydrogen resistant bearing steel. Existing hydrogen resistant steels are not appropriate for bearings due to their low hardness. The proposed microstructure combines a martensitic matrix in which fine cementite precipitates impart strength, and V4C3 nano-scaled particles acting as hydrogen traps. It is demonstrated that the conflicting objectives of ultra-hardness and hydrogen resistance can be concealed by: (1) Adding 0.5 wt.% V to 100Cr6, which allows to preserve existing steel production technology. (2) Following a novel heat treatment procedure consisting of austenitisation (and a subsequent temperature spike to dissolve coarse V4C3), followed by tempering at 600 degrees C where V4C3 particles form (and a subsequent temperature spike to dissolve coarse cementite), followed by quench and tempering at 215 degrees C, where fine cementite strengthening particles form. The enhanced trapping capacity of the new steel is demonstrated via thermal desorption; the presence of the desired microstructure after heat treatment is proved via transmission electron microscopy. Concomitant with the trapping ability, a significant hardness increase was observed; this was ascribed to the controlled V4C3 precipitation.

• 出版日期2013-1