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为探索珠光体基体稀土镁球墨铸铁经气体软氮化后高频淬火的复合强化效果,本文首先研究了复合处理工艺对其表层组织、相结构及硬度分布的影响,在此基础上对比了球铁四种处理工艺(正火、正火十软氮化、正火+高频淬火、正火+软氮化+高频淬火)的磨损性能和疲劳抗力。试验结果表明,球铁经软氮化高频淬火复合处理的强化效果显著。复合处理与单独软氮化和单独高频淬火相比,表层可得到极细的含氮马氏体,可进一步提高表层硬度值;在适当的奥氏体化加热条件下的硬化层深度增加并改善硬度梯度;在有润滑条件下复合处理具有最佳的耐磨性,在无润滑条件下只有在高接触应力时复合处理才显示其耐磨的优越性;在适当的硬化层深度下,球铁复合处理具有最高的缺口疲劳强度,比正火软氮化和高频淬火态分别提高61%、19.3%和11.4%。
In order to explore the composite strengthening effect of the pearlite matrix rare earth magnesium nodular iron cast by gas nitrocarburizing after high frequency quenching, this paper first studied the impact of composite treatment process on the surface microstructure, phase structure and hardness distribution, on this basis, compared the ball Iron four kinds of processing technology (normalizing, normalizing Ten soft nitriding, normalizing + high frequency quenching, normalizing + soft nitriding + high frequency quenching) wear resistance and fatigue resistance. The test results show that the strengthening effect of ductile iron by nitrocarburizing and high frequency quenching is remarkable. Compounded treatment Ultrafine nitrogen-containing martensite was obtained on the surface as compared with either nitrocarburizing alone or induction hardening alone, which further increased the surface hardness; the depth of the hardened layer increased under suitable austenitizing heating Improve the hardness gradient; composite treatment in the lubrication conditions have the best wear resistance, under no lubrication conditions only in high contact stress composite treatment showed its superior wear resistance; at the appropriate depth of the hardened layer, the ball The iron composite treatment has the highest notch fatigue strength, which is 61%, 19.3% and 11.4% higher than that of normalized soft nitriding and high frequency quenched respectively.