退火及回火处理对含Ni塑料模具钢性能的影响

Effect of Ni on the Microstructure and Mechanical Property of Annealing and Tempering Pre-hardened Plastic Mould Steel

通过研究2种不同成分的预硬型塑料模具钢锻后砂冷、退火及回火等状态下组织及力学性能并进行分析,发现退火组织由粒状贝氏体+下贝氏体+马氏体组成,降低粒状贝氏体量有利于提高材料的韧性和延伸率。残余奥氏体含量较低,对提高韧性作用不大。回火后残余奥氏体几乎全部分解,软相减少,屈服强度提高。Ni的增加降低了马氏体硬度,提高了贝氏体和退火后回火组织硬度。残余奥氏体对硬度的影响不大。

The microstructure and mechanical property of pre-hardened plastic mould steel that had gotten forged and heated treatment were studied. The microstructure of annealed steel witch was composed of granular bainite, lower bainite and martensite. The toughness and the elongation were increased when the volume of granular bainite was reduced. The re-sidual austenite did not improve the toughness for the little content. The decomposition of residual austenite had resulted in the increasing of the yield strength. The hardness of martensite was reduced and meanwhile increased the hardness of bainite and tempering microstructure after anealling because of the increase of Ni. This possible reason is that the Ni lowered theprecipitation of carbide. The residual austenite was the important reason of hardness change.