摘要
AISI H13热作模具钢中碳氮化物的析出会对钢的强度、硬度、韧性及耐疲劳等性能产生不利影响。对电渣重熔含铌H13钢锻造棒材中尺寸大于1μm的异相形核析出相的特征进行分析,同时利用热力学软件Thermo-Calc对其形成过程进行合理的解释。棒材中存在的析出相包含3层结构,中心为氧化物核心,主要为氧化铝或镁铝尖晶石,中间层为富Ti-V的碳氮化物相,最外层为富Nb碳氮化物相。2类碳氮化物相成分分布较为集中,富Ti-V相的平均成分为(Ti_(0.477)V_(0.336)Nb_(0.187))C_xN_y,富Nb的平均成分为(Ti_(0.128)V_(0.255)Nb_(0.617))C_xN_y。钢中观察到的析出相的尺寸甚至可以达到10μm以上。Thermo-Calc计算表明,核心镁铝尖晶石及氧化铝在凝固前即已生成,凝固过程中,当固相率达到0.823时,富Ti相依附于氧化物首先析出,随后富V相、富Nb相依次析出。在随后的热处理中,富V相溶解于富Ti相中,形成棒材中观察到的3层(Ti,Nb,V)(C,N)相。
The precipitation of carbonitride in H13 hot working die steel would be detrimental to the strength, hardness, toughness and fatigue resistance properties of steel. The characteristics of heterogeneous precipitates （Ti,Nb,V）（C,N） with the size larger than 1μm in a Nb containing H13 forging bar pre-produced by electro-slag remelting （ESR） process were studied. The generation mechanism was analyzed through calculation by Thermo-Calc software. Most of the precipitates observed consisted of three-layer structures. The center was an oxide core which was mainly MgO- Al2O3 spinel or Al2O3, the middle layer was a Ti-V-rich （Ti,Nb,V）（C,N） phase and the outer layer was a Nb-rich （Ti, Nb,V）（C, N） layer. The normalized compositional distributions of Ti, Nb and V in the Ti-V-rich and Nb-rich layers were concentrated. The average composition of Ti-V-rich layer was （Ti0.477 Vo. 336 Nb0.187 ） C, Ny and that of Nb-rich layer was （Ti0. 128 V0. 255 N0. 617 ） C, Nu. The size of the heterogeneous precipitates could be up to 10μm. The generation mechanism of the precipitates could be well speculated through Tbermo-Calc calculation. The spinel and alumina have already existed in the liquid steel before solidification. During solidification the Ti-rich phase will firstly start to precipitate on the oxide when the solid fraction reaches 0.823. Then the V-rich phase and Nb-rich phase will precipitate successively. During the subsequent heat treatment process, the V-rich phase will be dissolved in Ti-rich phase, resulting in the appearance of large precipitate with three-layer structure.
出处
《炼钢》
CAS
北大核心
2016年第5期36-40,61,共6页
Steelmaking
