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AISI P21塑料模具钢具有均匀的显微组织、严格的织构和预强化的可焊性,是理想的镜面抛光的塑料模具的模芯和模腔的材料。本项研究把渗氮和氧氮化热处理用于AISI P21塑料模具钢,调整各种工艺参数来确定渗氮处理对表面特性的影响。制备的试样用光学显微镜分析渗氮层的显微组织和渗层厚度;用X射线衍射仪(XRD)测定结构;用三维表面轮廓测定仪分析表面形貌和粗糙度;用极化腐蚀仪评定耐腐蚀性。还用洛氏硬度计测硬度。分析测试结果表明:把AISI P21塑料模具钢进行渗氮处理能有效提高表面硬度,而氧氮化的表面层能增加耐腐蚀性。含氮的表面层虽然相当硬,却比较脆。生成如Fe3N and Fe4N的氮化铁,它们能保持塑料模具的精确形状和延长使用寿命。
With uniform microstructure, tight texture and pre-strengthened weldability, AISI P21 plastic tool steel is the ideal material for the core and cavity of mirror-finished plastic molds. In this study, nitriding and oxynitrided heat treatment were applied to AISI P21 plastic mold steel to adjust various process parameters to determine the effect of nitriding on surface properties. The prepared samples were analyzed for the microstructure and the thickness of the nitrided layer by an optical microscope; the structure was determined by X-ray diffractometer (XRD); the surface morphology and roughness were analyzed by a three-dimensional surface profilometer; Evaluation of corrosion resistance. Rockwell hardness also measured. Analysis and test results show that: Nitriding AISI P21 plastic mold steel can effectively improve the surface hardness, while the oxynitridation of the surface layer can increase the corrosion resistance. Although the nitrogen-containing surface layer is rather hard, it is relatively brittle. Iron nitrides, such as Fe3N and Fe4N, are produced that maintain the exact shape and extend the useful life of plastic molds.