BHW35钢埋弧焊接头组织及高温力学性能研究
Research on Microstructure and Mechnical Properties at High Temperature of BHW35 Steel Welded Joint by SAW
王香云1,2，王文先1，王保东3，母蕊莲4
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作者单位：（1. 太原理工大学 材料科学与工程学院, 山西 太原030024; 2. 太原锅炉集团有限公司, 山西 太原030021; 3. 山西中通高技术公司, 山西 太谷030008； 4. 中国船舶重工集团第十二研究所，陕西 兴平 713102）
中文关键字：BHW35钢；焊接工艺；金相组织；高温力学性能；冲击韧度；断口分析
英文关键字：BHW35 steel; welding process; metallograph; mechanical properties at high temperature； impact toughness； fractograph
中文摘要：采用埋弧自动焊, 选用H10Mn2NiMoA+HJ350焊材匹配正火+回火+消应力退火(简称A方法)、H08Mn2MoA+HJ350焊材匹配消应力退火(简称B方法)两种方法制得BHW35钢厚壁焊接接头，分别进行了弯曲、冲击及拉伸试验，以及断口、金相组织及化学成分分析。探明A方法焊缝组织为粒状贝氏体+铁素体，HAZ为回火索氏体+贝氏体+铁素体； B方法焊缝组织为粒状贝氏体+索氏体+块、针状铁素体，HAZ为回火贝氏体+回火索氏体+沿晶屈氏体。母材组织为回火索氏体+贝氏体+铁素体。B方法晶粒较粗大，晶粒度差别亦大。两方法工艺及力学性能良好，室温下B方法接头强度高于A方法，而韧性低于A方法，冲击断口存在准解理+韧窝混合断裂特征，HAZ的韧性高于焊缝金属。高温下B方法接头强度降低比率较大，由于屈强比高，抗裂纹扩展破断能力不及A方法。该试验研究对BHW35钢高温高压工作环境下焊接结构的应用具有重要的理论价值和现实意义。
英文摘要：Using the methods of automatic submerged-arc welding, the BHW35 thick-wall welded joint was made. Welding wires includ H10Mn2NiMoA and H08Mn2MoA matched with two postweld heat-treatment systems individual shortened method A and method B. The experiment applied mechanical properties of bend, tension and impact on the welded joint and base metal, furthermore, its metallograph and SEM fractograph of impact fracture were analyzed. The results indicate that method A welding seam metallograph consist of granular bainite and ferrolites. The microstructure of HAZ is sorbite, bainite and ferrolites. The method B welding seam metallograph consist of granular bainite, sorbite and ferrolites. The microstructure of HAZ is temper bainite, sorbite, and intergranular troostite. The base metal metallograph consist of tempereted sorbite, bainite and ferrolites. The grain size of methods B is coarsening, at room temperature the interval of grain degree is larger. The welding process and properties of both method are satisfied. The strength of welded joint by method B is better than that by method A, and toughness is lower than that by method A. SEM fractograph indicate that the impact fracture by method B exhibit quasi-cleavage and ductile dimple, that by method A all exhibit ductile dimple. The impact toughness in HAZ is better than that in welding seam. The strength reduced ratio of welded joint in method B is higher than method A at high temperature. Due to higher yield ratio, the ability of crack extended resistance of welded joint by method B are lower than that by method A. This study has significant theoretical and applied value on welding structure of BHW35 steel at the high temperature and pressure environment.