合金元素对热作模具钢高温强度的影响及新型压铸模用钢的研制

The Effect of Alloying Elements on High-Temperature Strengthand the Development of Hot Work Tool Steel for Die-Casting Die

在工作过程中由于循环热负荷引起的热疲劳裂纹是压铸模具钢的常见问题之一,对于模具材料始终保持良好的高温强度和韧性是材料设计的目标。通过采用100公斤VIM冶炼不同Cr、Mo和V含量的钢锭,研究了碳化物形成对性能的影响。结果表明,为了设计具有良好的抗软化性能的新材料,提高M_(2)C型碳化物数量具有明显的效果,另一方面,材料的韧性随着M_(6)C、M_(2)C和MC型碳化物数量的增加而降低。从这些结果来看,合理控制Mo和V含量是兼顾高温强度和韧性的关键。另外,随着V含量的增加和Mo含量的减少,M_(2)C碳化物的含量呈上升趋势。在此基础上,通过优化合金设计,从控制析出碳化物类型和数量的角度出发,开发研制了QDX-HARMOTEX热作模具钢。QDX-HARMOTEX钢具有良好的韧性和抗软化性,并具有优良的抗热疲劳裂纹性。

Heat checking,caused by cyclic thermal load during the operation,is one of the common damages to diecasting dies.It is ideal for die steels to retain well-balanced high-temperature strength and toughness for good resistance to heat checking.In this report,the effect of carbide-forming elements on these properties was investigated by use of several 100kg VIM ingots of steels with varied Cr,Mo and V.As a result,in order to design the steel with good softening resistance,it is effective to increase the amount of M_(2)C carbide.On the other hand,toughness tends to decrease with increases of the total amounts of M_(6)C,M_(2)C and MC types of carbide.From these results,controlling the amounts of Mo and V is critical taking consideration of both high-temperature strength and toughness.In addition,it was found that the amount of M_(2)C carbides tends to increase with an increase of V content and with a decrease of Mo content.Based on the above knowledge,hot-work tool steel QDX-HARMOTEX is developed from the.standpoint of controlling types and amounts of precipitated carbides by optimization of alloy design.With its excellent toughness and sofening resistance,QDX-HARMOTEX demonstrates excellent heat checking resistance.