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球铁的预处理分别采用900℃正火,900℃正火以及在不同温度回火,以获得不同含量的铁素体。QPQ(Quench淬火-Polish抛光-Quench淬火)复合盐浴处理工艺为:在580℃的氮化盐浴中氮化3h后再在370℃的氧化盐浴中氧化30min。用金相显微镜和X射线衍射仪研究了球铁QPQ复合盐浴处理工艺后的显微组织,用M200滑动磨损试验机研究了球铁经过不同工艺处理后的耐磨性。结果表明,QPQ复合盐浴处理后的渗层主要由Fe2N和Fe3O4组成;随着球铁中铁素体含量的增加,其渗层厚度增加。经过QPQ复合盐浴处理的球铁试样的耐磨性显著高于淬火加低温回火试样的耐磨性;有氧化层的耐磨性比仅仅有氮化物的耐磨性稍稍高一些。
Ductile iron pretreatment were normalized at 900 ℃, normalized at 900 ℃ and tempered at different temperatures to obtain ferrite with different contents. The QPQ (Quench Quench-Polish-Quench Quench) composite salt bath treatment was nitrided in a nitride bath at 580 ° C for 3 h followed by oxidation in a 370 ° C salt bath for 30 min. The microstructure of the QPQ composite salt bath was studied by metallographic microscope and X-ray diffractometer. The wear resistance of the ductile iron after different treatment was studied by M200 sliding wear tester. The results show that the infiltration layer of QPQ composite salt bath is mainly composed of Fe2N and Fe3O4. With the increase of ferrite content in ductile iron, the thickness of infiltrated layer increases. The wear resistance of the ductile iron specimens treated with QPQ composite salt bath was significantly higher than that of the quenched and tempered specimens. The wear resistance of the oxide layer was slightly higher than that of the nitride alone.