Surface Durability of Developed Cr-Mo-Si Steel under Rolling-Sliding Contact

Abstract

To develop case-carburized gears with high loading capacity, the surface durability of a developed Cr-Mo-Si steel (with 1 mass% Si added in the chemical composition) was studied. Initially, the fatigue tests of case-carburized Cr-Mo-Si steel and Cr-Mo steel melted in a hypoxia vacuum were carried out using a two-roller contact fatigue tester. Next, the changes in the surface failure, surface roughness and sectional hardness distribution of the test rollers were examined using a scanning electron microscope, a surface roughness measuring instrument and a penetrometer, respectively. In the case of Cr-Mo-Si steel test rollers under rolling-sliding contact, the following results are obtained in comparison with Cr-Mo steel test rollers: micro pitting area ratio is lower under a medium load, the pits do not occur under a heavy load, and the value of surface variation is lower. Therefore, it is clear that the developed Cr-Mo-Si steel can be applied to case-carburized gear materials under a heavy load.

Keywords

• gear
• roller
• material
• alloy steel
• carburizing
• surface failure
• surface durability
• surface roughness
• hardness