温度对40Cr钢温挤压成形的摩擦--磨损性能影响

采用温挤压技术对40Cr钢进行成形试验,考察了不同温度下温挤压试样的摩擦-磨损行为.通过扫描电镜、能谱仪和X射线衍射仪分析了40Cr钢磨损后表面形貌、化学元素分布和物相组成,讨论了40Cr钢温挤压的磨损机理.结果表明,在挤压温度为550℃时试样晶粒尺寸细小,残余奥氏体含量较高,硬度最高,其磨损性能为最佳;而当温度为650℃和750℃时,晶粒尺寸较粗大,残余奥氏体含量降低.在5N载荷作用下,挤压温度为550℃时,摩擦因数为0.7667;当挤压温度达到650℃,摩擦因数为0.8587,提高了12.01%,磨损性能降低;750℃时,摩擦因数为0.8764,相比550℃提高了14.31%,磨损性能进一步变差;在550、650和750℃时,磨损形式主要为磨粒磨损.

Effects of temperature on the friction--wear properties of 40Cr steel by warm extrusion

A forming experiment of 40Cr steel was conducted by using a warm extrusion technology, and the friction- wear behavior of the samples at different extrusion temperatures were observed. The wear morphologies, distributions of chemical elements and phase compositions were analyzed by scanning electronic microscopy (SEM), energy diffusive spectrometry (EDS), and X-ray diffraction (XRD), respectively, and the wear mechanism of warm extrusion on 40Cr steel was discussed. The results show that the grains are samll by warm extrusion at 550℃, the content of retained austenite is higher, and the hardness is the highest, showing that the wear resistance is the best. The size of grains is bigger and the contents of retained austenite decrease at the extrusion temperature of 650℃ and 750℃. The coefficient of friction is 0. 7667 at the extrusion temperature of 550℃ under the load of 5 N, while that is 0. 8587 at the extrusion temperatures of 650℃, which increases by 12. 01%, and the wear performance decreases. At the extrusion temperature of 750℃, the coefficient of friction is 0. 8764, which increases by 14. 31% compared with 550℃, and the wear perform-ance is worse. The wear forms of the samples at 550, 650 and 750℃ are common abrasive wear.