中文摘要：

H13热作模具钢在1303 K淬火后,用金相显微镜观察不同部位的组织及变化规律,用碳膜萃取复型,通过透射电镜、电子衍射和能谱分析碳化物类型,统计碳化物的析出量和平均尺寸,考察各部位碳化物对屈服强度的贡献.结果表明,H13钢经淬火后由珠光体变为马氏体和残余奥氏体,碳化物主要为V8C7和Cr23C6.由钢锭芯部到1/2R（R为钢锭半径）处,碳化物平均尺寸决定强化贡献,而由1/2R处到钢锭表面,碳化物含量决定强化贡献.随析出物增多和粒度减小,钢强度、韧性均有提高.

英文摘要：

Thermodynamic calculation of H13 steel during solidification in solid phase is carried out to define the precipitate temperature of V8C7（1 545.7 K） and Cr23C6（1 055.3 K）.After 1 373 K quenching of die H13 steel,the microstructure and variation in H13 steel are observed with optical microscope.Through deploying carbon extraction replica technique,using TEM,electron diffraction and EDS,the amount,average size and type of carbides are analyzed,and the contribution of three parts of steel to yield strength is explored.The results show that the microstructure in H13 steel after quenching is changed from pearlite to martensite and residual austenite.The precipitates mainly include V8C7 and Cr23C6.From the center to 1/2 radius of ingot,the average size of carbides determines the strengthening contribution.From 1/2 radius to surface,the volume fraction of carbides determines the strengthening contribution.The overall mechanical properties of H13 steel become excellent as the number of precipitates increases and particle sizes become smaller.