热轧H13钢硬度不均匀性的分析

 对H13钢试样进行了退火试验，对退火前后试样进行了硬度测试及扫描电镜和能谱分析。分析了H13钢热轧材硬度不均匀性的形成原因。结果表明，低倍“黑斑”区域硬度平均值为91.43HRB，比正常区域高7.53%；“黑斑”区域主要由“白斑”和“黑色质点”组成，“白斑”化学成分主要是铁，“黑色质点”主要成分为合金碳化物；H13钢试样经退火后，原“黑斑”区域硬度明显降低，从190.2HB下降到168.26HB，退火后“黑色质点”尺寸变小，其碳质量分数大幅度降低，从80%下降到15%；H13钢热轧材硬度不均匀主要是由于钢液凝固过程中成分不均匀所致。

Analysis of the Hardness Inhomogeneity in Hot-Rolled Product of H13 Steel

Annealing experiment was performed,and the samples before and after annealed were studied by SEM(Scanning Electron Microscope) and EDS(Energy Disperse spectroscopy).The hardness of samples was tested.The reasons causing the hardness inhomogeneity in hot-rolled product of H13 steel were analyzed.The results show that the hardness of freckle area is 91.43 HRB,7.53% higher than the hardness of normal area.The freckle area is mainly comprised of white spot and black particle,the main chemical composition of white spot is iron and the black particle is alloy carbide.After the H13 samples were annealed,the hardness of freckle area decreased obviously,from 190.2 HB to 168.26 HB.The size of black particle is smaller,and its carbon percentage content decreased significantly,from 80% to 15%.The hardness inhomogeneity in hot-rolled product of H13 steel is mainly due to non-uniform composition of molten steel during the casting solidification process.