不同冶炼工艺生产H13钢中非金属夹杂物特征及其对力学性能的影响

Characteristics of Non-metallic Inclusions in H13 Steel Produced by Different Smelting Processes and Their Effect on Mechanical Properties

采用真空感应+真空自耗(VIM+VAR)、电弧炉+炉外精炼+真空脱气+保护气氛电渣重熔(EAF+LF+VD+PESR)、EAF+LF+VD以及EAF+LF+VD+电渣重熔(ESR)等4种工艺冶炼H13热作模具钢,并进行高温扩散、轧制、奥氏体化和回火处理,研究了不同冶炼工艺生产H13钢中非金属夹杂物特征及其对力学性能的影响。结果表明:4种冶炼工艺生产的试验钢回火组织均为回火马氏体+未溶碳化物+析出碳化物;VIM+VAR工艺生产的试验钢中非金属夹杂物含量最少且尺寸较小,该钢的洁净度较高,力学性能最佳;EAF+LF+VD工艺生产的试验钢中非金属夹杂物含量最高且尺寸大,其碳化物质点易发生破碎,该钢的塑性最低。细小且数量少的非金属夹杂物在拉伸过程中不易作为裂纹源加速材料断裂,因此较高的洁净度可以提高H13钢的力学性能。

H13 hot-working die steel was smelted by vacuum induction melting+vacuum arc remelting(VIM+VAR),electric arc furnace+ladle furnace+vacuum degasses+protective atmosphere electroslag remelting(EAF+LF+VD+PESR),EAF+LF+VD and EAF+LF+VD+electroslag remelting(ESR)processes,and then was treated with high temperature diffusion,rolling,austenitizing and tempering.The characteristics of non-metallic inclusions in H13 steel produced by different smelting processes and their effect on mechanical properties was studied.The results show that the tempered microstructure of the test steel produced by four smelting processes was composed of tempered martensite+undissolved carbide+precipitated carbide.The test steel produced by VIM+VAR process had the lowest content and small-sized non-metallic inclusions,indicating high cleanliness,which led to the best mechanical properties.The test steel produced by EAF+LF+VD process had the highest content and large size of non-metallic inclusions,and the carbide particle breakage appeared,resulting in the lowest plasticity of the steel.Small and few nonmetallic inclusions were not easy to be crack sources to accelerate material fracture during the tension process,so higher cleanliness could improve the mechanical properties of H13 steel.