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利用Gleeble3800型热力模拟试验机对40Cr试样进行热压缩试验,得到不同温度和应变速率下的应力-应变曲线。用XRD、SEM和OM对热压缩后试样表面物相和金相形貌进行表征,分析了不同温度和不同应变速率下,热压缩对试样表面组织性能的影响。结果表明:变形抗力与应变速率成正比,与试验温度成反比,残留奥氏体含量同样遵循此规律;650℃时表面以片状珠光体为主,750℃时表面组织以马氏体和贝氏体为主,随着温度升高,材料表面出现轻微氧化;在650℃时可获得约350 MPa的平均残余应力,且在同一温度下,应变速率的提高有利于提高表面残余应力,这将有利于提高材料的抗疲劳性能。
The 40Cr samples were subjected to hot compression tests using the Gleeble 3800 thermal simulation machine to obtain the stress-strain curves at different temperatures and strain rates. The phase and microstructure of the sample after hot compression were characterized by XRD, SEM and OM. The effect of thermal compression on the microstructure and properties of the sample was analyzed under different temperatures and different strain rates. The results show that the deformation resistance is proportional to the strain rate and inversely proportional to the test temperature. The residual austenite content also follows this rule. The surface is dominated by lamellar pearlite at 650 ℃. The martensite and shell at 750 ℃ With the increase of temperature, the surface of the material appears slight oxidation. The average residual stress of about 350 MPa can be obtained at 650 ℃, and at the same temperature, the increase of strain rate is helpful to improve the surface residual stress Help to improve the material’s fatigue resistance.