材料期刊网

目的 研究540℃氮化温度下,QPQ处理对H13钢耐磨性的影响并选出最优氮化时间.方法 通过SEM、EDS、XRD分别测试了H13钢QPQ处理后渗层微观组织形貌、成分分布以及物相组成.采用HVS-1000显微硬度计、MFFT-R4000高速往复摩擦磨损试验,分别对H13钢基体与540℃下不同氮化时间QPQ处理试样的渗层厚度、硬度分布、耐磨性进行了分析研究.结果 QPQ处理后,H13钢由表面向心部依次形成均匀致密的Fe3O4氧化膜、高硬度的ε-Fe3N和CrN化合物层、α-Fe和Cr2N稳定扩散层.N原子均匀分布于渗层内部.显微硬度沿截面均呈良好梯度分布.在540℃×4 h氮化工艺下,渗层次表层硬度达到最大值(1173HV0.1),是基体(498HV0.1)的2.4倍左右,磨损量仅为基体的1/13.H13钢磨损表面存在严重犁沟效应与大量磨屑,表现为典型的磨粒磨损伴随少量粘着磨损.而QPQ处理试样磨损表面仅存在少量浅显划痕,并伴随轻微结疤状凹坑,为粘着磨损.结论 经QPQ处理,H13钢的耐磨性得到了显著提高,其中氮化工艺为540℃×4 h时所得的性能最优.

The work aims to study effects of QPQ treatment on wear resistance of H13 steel at the nitridation temperature of 540℃. The microstructure morphology, composition distribution and phase composition of H13 steel subject to treatment were tested with SEM, EDS and XRD respectively. HVS-1000 microhardness tester and MFFT-R4000 high speed-reciprocated-wear experiment were used to analyze and study nitride layer thickness, microhardness distribution and wear resistance of H13 steel substrate and samples subject to QPQ treatment for different nitridation duration at 540℃. After the QPQ treatment, the uni-form and dense (Fe3O4) oxide film, extreme hardε-Fe3N and CrN compound layer as well asα-Fe and Cr2N stable diffusion layer were formed successively on H13 steel from the surface to center. N atoms were uniformly distributed inside. The micro-hardness had favorable gradient distribution along the cross section. Provided with the nitridation process of 540℃×4 h, sub-surface microhardness of the layer reached the peak (1173HV0.1), 2.4 times higher than that of substrate (498HV0.1). Weight loss was only 1/13 of that of QPQ specimen. Serious plowing effect and plenty of wear debris, appearing to be typical abrasive wear accompanied with slight adhesive wear, were present on wear surface of H13 steel. Only adhesive wear appearing to be slight shallow scratches accompanied with few scar pits was present in the wear surface of QPQ treatment sample. After QPQ treat-ment, wear resistance of H13 steel is improved significantly, optimal performance is provided with nitridation process of 540℃×4 h.