河北冶金

热挤压模具长期承受高温、交变热应力、高压摩擦耦合载荷，易出现热疲劳、磨损、塑性变形等失效，模具钢材质直接决定模具服役寿命。本文系统梳理国内热挤压模具钢产业发展现状，归纳模具典型服役工况、主要失效模式及高温强韧、抗冷热疲劳、耐磨抗黏结三大核心性能指标。依据合金总含量与适用温度区间，将国内商用热挤压模具钢划分为低合金基础型、中合金耐热型、高合金强耐热三大系列，分类整理5CrNiMo、H13、RM2等主流牌号化学成分、力学特性与适用挤压场景，对比各类钢服役优劣。综述国内高校、钢厂近年新型稀土微合金、硼氮强化热作模具钢研发成果，梳理R522、SDH、DH360Re等自研钢的性能提升幅度与应用优势。结合新能源汽车、航空高端挤压产业需求，预判行业将向超高温强韧材质、长寿命低成本钢种、精密纯净材料三大方向升级；提出稀土/硼复合微合金化、超纯净冶炼、一体化全流程服务是核心技术路径，完善“成分设计-热处理-表面强化-寿命评估-修复”全链条方案可显著延长模具服役周期，可为挤压制造企业选材、新型模具钢开发及质量优化提供理论参考与工程依据。

Hot extrusion dies are subjected to coupled loads of high temperature, cyclic thermal stress and high pressure friction for a long service period. They are prone to failure forms including thermal fatigue, wear and plastic deformation. The material property of die steel directly determines the service life of dies. This paper systematically sorts out the industrial development status of domestic hot extrusion die steels. Typical service conditions and main failure modes of dies are summarized. Three core performance indicators are concluded. These indicators cover high temperature strength toughness, thermal cold fatigue resistance and wear adhesion resistance. According to the total alloy content and applicable temperature range, domestic commercial hot extrusion die steels are divided into three series. The three categories are low alloy basic type, medium alloy heat resistant type and high alloy extra heat resistant type. The chemical composition, mechanical properties and applicable extrusion scenarios of mainstream grades such as 5CrNiMo, H13 and RM2 are sorted out by category. The service advantages and disadvantages of different steel grades are compared. Recent research achievements of novel rare earth microalloyed and boron nitrogen strengthened hot work die steels developed by domestic universities and steelmakers are reviewed. The performance improvement range and application superiority of self developed steels including R522, SDH and DH360Re are summarized. In view of the market demands from new energy vehicle and high end aerospace extrusion industries, three major upgrading trends of this industry are predicted. The development directions are ultra high temperature strength toughness materials, long life and low cost steels and high purity precision materials. Rare earth/boron composite microalloying, ultra clean smelting and integrated whole process service are proposed as the core technical routes. A complete solution chain of "composition design heat treatment surface strengthening life evaluation repair" can significantly prolong the service cycle of dies. This study can provide theoretical reference and engineering basis for material selection of extrusion manufacturers, new type die steel development and quality optimization.