Carbide Evolution Behavior of GCr15 Bearing Steel During Aging Process

被引：0
|
作者：
Liu Z. [1 ,2 ]
Li Y. [1 ,2 ]
Liu Y. [1 ]
Wang P. [1 ]
Li D. [1 ]
机构：
[1] Institute of Metal Research, Chinese Academy of Sciences, Shenyang
[2] School of Materials Science and Engineering, University of Science and Technology of China, Shenyang
来源：
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | 2024年 / 38卷 / 02期
关键词：
aging treatment; carbide evolution; cryogenic treatment; GCr15; Impact toughness; metallic materials;
D O I：
10.11901/1005.3093.2023.169
中图分类号：
学科分类号：
摘要：
The evolution behavior of carbides in GCr15 bearing steel and its influence on the impact toughness during long-term aging at 170oC have been investigated by means of SEM, TEM, and XRD, aiming to meet the requirements of vacuum dry pump bearings. The results demonstrate that after quenching at 840oC and the tempering at 230oC, the hardness of GCr15 steel remains above 59 HRC with minimal retained austenite, which is favorable to the enhancement of performance and dimensional stability for the steel at 170oC. During the aging process, carbon atom partitioning and carbide precipitation lead to a decrease in carbon concentration, lattice distortion and micro-zone stress strain of the matrix, while transitional carbides precipitate, coarsen and then transform into non-coherent cementite. The resultant effect of these microstructural variation is a reduction in material hardness, while the impact toughness initially increasing and then decreasing. However, the cooperative effect of the decarbonization of martensite and carbide type transformation makes hardness of steels remain stable or even increase a little in between 1000 h and 2000 h during the aging process. To improve the microstructure and performance stability during the aging process, cryogenic treatment was conducted after quenching. The introduction of high-density defects promotes effective carbon distribution during tempering and aging, which gives rise to uniform distribution and size control of fine carbides. Cryogenic treatment reduces the carbide growth rate from 298 nm3/h to 229.5 nm3/h, which delays the performance decline effectively and makes the GCr15 bearing steel satisfied with demands of vacuum dry pump bearings. © 2024 Chinese Journal of Materials Research. All rights reserved.
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页码：130 / 140
页数：10
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