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用35CrMo 钢做缺口疲劳试棒,分别进行了液氨离子氮化处理(氮化层厚为0.3mm)和气体氮化处理(氮化层厚0.50mm)随后进行了缺口疲劳对比试验。结果前者的缺口疲劳极限为σ_(-1k)=54kgf/mm~2,后者为σ_(-1k)=50kgf/mm~2。这可能是:①离子氮化处理的致密的化合层抑制或推迟疲劳裂纹的产生和扩展;②离子氮化处理所产生的表面残余压应力比气体氮化的大。对于表面强化的零件,由于负荷性质、应力状态和工件形状的不同,其失效过程及硬化层各种组织在失效时所起的作用也不一
With 35CrMo steel as notch fatigue test bar, liquid ammonia ion nitriding (nitrided layer thickness of 0.3mm) and gas nitriding (nitrided layer thickness of 0.50mm) were followed by a notch fatigue test. Results For the former, the notched fatigue limit is σ _ (-1k) = 54kgf / mm ~ 2 and the latter is σ _ (-1k) = 50kgf / mm ~ 2. This may be: (1) dense nitrocarburized composite layer inhibits or postpone the generation and expansion of fatigue cracks; (2) the residual compressive stress generated by ion nitriding is larger than that of gas nitriding. For surface strengthened parts, due to the nature of the load, the stress state and the shape of the workpiece, the failure process and hardened layer of various organizations in the failure of a role