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一、前言 4Cr5MoWVSi钢(美国钢号H_(12),日本为SKD_(62))是常用的典型热模具钢,具有良好的室温和高温力学性能,广泛用于挤压模、压铸模或热锻模等。该钢的正常淬火组织为马氏体,调质处理后为回火马氏体或回火索氏体。但是,对于大型模具,由于淬火时冷却速度较低,表面为马氏体,心部或接近于心部有可能形成贝氏体或屈氏体的混和组织。有关混合组织对4Cr5MoWVSi钢性能的影响很少有详细报导。热模具的主要失效类型是开裂,其基本过程是:①裂纹的形成;②在交变应力下裂纹的扩展;③当裂纹扩展到临界尺寸时,模具开裂。上述三个阶段均与材料的性能(如
I. Introduction 4Cr5MoWVSi steel (American steel H_ (12), Japan SKD_ (62)) is a typical hot die steel commonly used in the room temperature and high temperature mechanical properties, are widely used in extrusion die, die-casting mold or hot forging Die and so on. The normal quenching of the steel martensite, quenched and tempered martensite or tempered sorbite. However, for large molds, the bainite or troostite mixed structure may form due to the lower cooling rate on quenching, martensite on the surface, or near or at the heart. The impact of mixed organizations on the performance of 4Cr5MoWVSi steels is rarely reported in detail. The main failure mode of hot die is cracking, the basic process is: ① the formation of cracks; ② crack extension under alternating stress; ③ when the crack extends to the critical size, the mold cracking. The above three stages are related to the material properties (eg