【作者】 宁玫； 李志群； 韩永明； 孙梅红； 杨翠丽； 芦居桂； 于潜；

【Author】 Ning Mei;Li Zhiqun;Han Yongming;Sun Meihong;Yang Cuili;Lu Jugui;Yu Qian;Technology Center of Tianjin Pipe Group Corporation;

【机构】 天津钢管集团股份有限公司技术中心；

【摘要】 限动芯棒的工作环境极为恶劣,需要在高温下承受很大的复杂循环应力,其冲击性能,尤其是横向冲击性能是影响其使用寿命的重要因素。借助于光学显微镜和扫描电镜,分析研究了进口和国产H13芯棒的组织差异,结果表明:进口芯棒组织均匀,晶粒细小,横向冲击性能较高。而国产芯棒存在严重的枝晶偏析和带状偏析、偏析带中有较多块状共晶碳化物和碳氮化物、晶界存在二次碳化物、基体晶粒相对较大等是导致其横向冲击性能偏低的主要原因。建议该厂采用炉外精炼、保护气氛电渣重熔、高温均质化处理、超细化处理、多向锻造等技术提高钢的纯净度,削减碳化物带状偏析,均匀及细化组织及碳化物,从而提高H13芯棒的横向冲击性能及热疲劳性能。更多还原

【Abstract】 The impact property, especially in transverse direction, of the retained mandrel is the important factor which can severely affect its service-span, due to its tough service environment and the complicated periodical stresses endured at high temperature. By means of optical microscopy and SEM, the microstructural differences of imported and domestic H13 retained mandrel are analyzed. The analysis results show that, the imported mandrel has uniform microstructure, very fine grains and high transverse impact property, whereas severe dendritic segregations, band segregations, lumpy eutectic carbides and carbonitrides found in segregation bands, proeutectoid carbides found in grain boundaries, coarse grain size, and etc, can be found in domestic mandrels, which can be the major reasons of the low impact property in transverse direction. It’s suggested that the increase of the purity of steel, the reduction of banding segregations of carbides, and homogeneous fine microstructure and carbides can improve the transverse impact property and thermal fatigue performance, by means of the technologies, such as secondary refining, electroslag remelting under gases, high temperature homogenization treatment, superfining treatment, multiple forging process, and etc.更多还原