Microstructure and property of bearing steel with and without nitrogen addition were investigated by microstructural observation and hardness measurement after different heat treatment processing. Based on the microst...Microstructure and property of bearing steel with and without nitrogen addition were investigated by microstructural observation and hardness measurement after different heat treatment processing. Based on the microstructural observation of both 9Cr18 steel and X90N steel, it was found that nitrogen addition could effectively reduce the amount and size of coarse carbides and also refine the original austenite grain size. Due to addition of nitrogen, more austenite phase was found in X90N steel than in 9Cr18 steel. The retained austenite of X90N steel after quenching at 1050℃ could be reduced from about 60% to about 7 9% by cold treatment at -73℃ and subsequent tempering, and thus finally increased the hardness up to 60 HRC after low temperature tempering and to 63 HRC after high temperature tempering. Furthermore, both the wear and corrosion resistance of X90N steel were found much more superior than those of 9Cr18 steel, which was attributed to the addition of nitrogen. It was proposed at last that nitrogen alloying into the high chromium bearing steel was a promising way not only to refine the size of both carbides and austenite, but also to achieve high hardness, high wear property and improved corrosion resistance of the stainless bearing steel.展开更多
Microstructure, hardness and fatigue properties of X30N high nitrogen stainless bearing steel were investigated. It was found that nitrogen addition could effectively reduce the amount and size of coarse carbides. The...Microstructure, hardness and fatigue properties of X30N high nitrogen stainless bearing steel were investigated. It was found that nitrogen addition could effectively reduce the amount and size of coarse carbides. The original austenite grain size was obviously refined. Additionally, more retained austenite was found in X30N steel after quenching at 1050 ℃, which could be reduced from about 30% to about 6% by cold treatment at - 73 ℃ and subsequent tempering, and thus, the ultimate hardness was increased up to about 61 HRC with reduction of austenite and precipitation of carbonitrides. Furthermore, the rolling contact fatigue lives of X30N steel ate superior to those of 440C steel, which was attributed to the enhanced hardness and a certain retained austenite in the high nitrogen steel.展开更多
基金supported by National Natural Science Foundation of China (51371057)International Project Collaboration between CISRI (P.R.China) and COMTES FHT a.s (Czech Republic)
文摘Microstructure and property of bearing steel with and without nitrogen addition were investigated by microstructural observation and hardness measurement after different heat treatment processing. Based on the microstructural observation of both 9Cr18 steel and X90N steel, it was found that nitrogen addition could effectively reduce the amount and size of coarse carbides and also refine the original austenite grain size. Due to addition of nitrogen, more austenite phase was found in X90N steel than in 9Cr18 steel. The retained austenite of X90N steel after quenching at 1050℃ could be reduced from about 60% to about 7 9% by cold treatment at -73℃ and subsequent tempering, and thus finally increased the hardness up to 60 HRC after low temperature tempering and to 63 HRC after high temperature tempering. Furthermore, both the wear and corrosion resistance of X90N steel were found much more superior than those of 9Cr18 steel, which was attributed to the addition of nitrogen. It was proposed at last that nitrogen alloying into the high chromium bearing steel was a promising way not only to refine the size of both carbides and austenite, but also to achieve high hardness, high wear property and improved corrosion resistance of the stainless bearing steel.
基金This research is supported by the National Natural Science Foundation of China （No. 51371057）, the National Key Research and Development Plan （No. 2016YFB0300101） and Beijing Natural Science Foundation （No. 2182088）.
文摘Microstructure, hardness and fatigue properties of X30N high nitrogen stainless bearing steel were investigated. It was found that nitrogen addition could effectively reduce the amount and size of coarse carbides. The original austenite grain size was obviously refined. Additionally, more retained austenite was found in X30N steel after quenching at 1050 ℃, which could be reduced from about 30% to about 6% by cold treatment at - 73 ℃ and subsequent tempering, and thus, the ultimate hardness was increased up to about 61 HRC with reduction of austenite and precipitation of carbonitrides. Furthermore, the rolling contact fatigue lives of X30N steel ate superior to those of 440C steel, which was attributed to the enhanced hardness and a certain retained austenite in the high nitrogen steel.
文摘高硬度淬硬钢高速铣削过程具有高铣削速度和高加工表面硬度的特性,平稳高效的铣削能保证加工质量和精度,铣削振动的产生限制了硬态切削技术优越性的发挥。通过设计在不同加工工艺参数条件下涂层刀具高速铣削高硬度(HRC 48~68)淬硬钢试验,使用LMS Test 9A测试分析软件采集铣削振动信号,进行时域和频域分析,研究铣削振动与淬硬钢材料硬度、铣削工艺参数的关系。结果表明:淬硬钢工件材料硬度提高,将使涂层刀具前刀面与淬硬钢工件材料的摩擦增大,进给方向摩擦阻力增大,振动信号幅值增大;TiAl N和AlCrN涂层刀具铣削时产生的振动信号相对TiSiN和CrSiN涂层刀具偏小,涂层设计过程中Al元素的添加对抑制和减少淬硬钢铣削振动有积极作用;铣削工艺参数值的变化对刀具进给方向铣削振动的影响各不相同,其中铣削速度的变化使铣削振动产生一个振动极值点;为了获得较小的铣削振动幅值和较高的铣削效率,优先选择的铣削参数值应使铣削振动尽可能减小。
