强化研磨喷射压力对GCr15轴承钢应力腐蚀性能的影响

Effect of Strengthened Grinding Jet Pressure on Stress Corrosion Properties of GCr15 Bearing Steel

为研究GCr15轴承钢在腐蚀环境与应力联合作用下的失效行为及强化研磨对其应力腐蚀性能的影响,以喷射压力为参数变量,对强化研磨加工后的试样材料在NaCl溶液中进行慢应变速率拉伸实验,并对其断口进行SEM形貌观测,分析不同喷射压力加工后试样应力腐蚀敏感性。结果表明:空白组应力腐蚀敏感性为0.28,经不同喷射压力加工后分别为0.241、0.212、0.177、0.145、0.131,表现出随着喷射压力增大而减小的趋势;其中强化研磨加工后试样损失力学性能程度降低,喷射压力为0.8 MPa时损失的力学性能最少,抗拉强度降低171.8 MPa,延伸率减少0.8%;GCr15轴承钢发生应力腐蚀断裂的类型为沿晶断裂。与空白组相比,加工后试样断口形貌中准解理平面数量减少,韧窝数量增多,脆化程度降低。强化研磨加工后在材料表层引入残余压应力,晶粒细化形成致密强化层,缓解应力集中并阻碍裂纹的萌生扩展,导致腐蚀介质难以侵入基体产生腐蚀。因此GCr15轴承钢材料应力腐蚀抗性在机械应力强化和微观组织强化共同作用下得到综合提升。

In order to study the failure behavior of GCr15 bearing steel under the combined action of corrosive environment and stress and the effect of enhanced grinding on its stress corrosion performance.Taking the injection pressure as the parameter variable,a slow strain rate tensile test was carried out on the sample material after strengthening grinding in NaCl solution,and the fracture surface was observed by SEM,and the stress corrosion stress corrosion susceptibility of the sample after different injection pressure processing was analyzed.The results show that the stress corrosion susceptibility of the blank group is 0.28,and it is 0.241,0.212,0.177,0.145,and 0.131 after processing by different injection pressures,showing a decreasing trend with the increase of injection pressure.The degree of loss of mechanical properties is reduced.When the injection pressure is 0.8 MPa,the loss of mechanical properties is the least,the tensile strength is reduced by 171.8 MPa,and the elongation is reduced by 0.8%;the type of stress corrosion cracking of GCr15 bearing steel is intergranular fracture.Compared with the blank group,the number of quasi-cleavage planes in the fracture morphology of the samples after processing decreased,the number of dimples increased,and the degree of embrittlement decreased.After the enhanced grinding process,residual compressive stress is introduced into the surface of the material,and the grains are refined to form a dense and strengthened layer,which relieves stress concentration and hinders the initiation and expansion of cracks,making it difficult for corrosive media to invade the matrix and cause corrosion.Therefore,the stress corrosion resistance of GCr15 bearing steel is comprehensively improved under the combined action of mechanical stress strengthening and microstructure strengthening.