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本文研究了球墨铸铁曲轴经正火、中频淬火、等温淬火、气体软氮化处理的组织、内应力与机械性能的关系,据以论证上述强化工艺的合理性。曲轴的平面弯曲疲劳试验表明:与正火态相比,经570℃气体碳氮共渗4小时处理,疲劳强度提高了68%;280℃等温淬火可提高48%;轴颈中频淬火强化只能提高耐磨性,由于淬火热影响区的弱化和园角处表层的残余拉应力的不利影响,其疲劳强度低于正火曲轴。与尿素热分解软氮化工艺相比,通氨滴醇软氮化工艺具有更好的强化效果。
In this paper, the relationship between the structure, internal stress and mechanical properties of nodular cast iron crankshaft by normalizing, medium frequency quenching, austempering, gas nitrocarburizing was studied. The rationality of the above strengthening process was demonstrated. The plane bending fatigue test of crankshaft shows that the fatigue strength increases by 68% compared with the normalized state after gas carbonitriding at 570 ℃ for 4 hours, while the isothermal quenching at 280 ℃ can be increased by 48% Improve the wear resistance, the fatigue strength is lower than that of the normalized crankshaft due to the weakening of the quenching heat-affected zone and the residual tensile stress of the surface layer at the corner. Compared with the urea thermal decomposition nitrocarburizing process, the ammonia ammoniacal nitriding process has a better strengthening effect.