焊接工艺对海工钢热影响区组织与性能的影响  

Effect of welding process on microstructure and properties of heat affected zone of marine steel

作　　者：朱立光 马晨雨 王旗 郑亚旭 肖鹏程 郭志红[1,2] ZHU Li-guang;MA Chen-yu;WANG Qi;ZHENG Ya-xu;XIAO Peng-cheng;GUO Zhi-hong(School of Materials Science and Engineering,Hebei University of Science and Technology,Shijiazhuang 050018,Hebei,China;Hebei Key Laboratory of Hebei Materials Near-net Forming Technology,Shijiazhuang 050018,Hebei,China;College of Metallurgy and Energy,North China University of Science and Technology,Tangshan 063210,Hebei,China)

机构地区：[1]河北科技大学材料科学与工程学院,河北石家庄050018 [2]河北省材料近净成形技术重点实验室,河北石家庄050018 [3]华北理工大学冶金与能源学院,河北唐山063210

出　　处：《钢铁》2023年第2期137-146,共10页Iron and Steel

基　　金：国家区域联合基金重点资助项目(U21A20114);河北省重点研发资助项目(20311003D);河北省自然科学基金资助项目(E2021208017,E2019208308,E2021208006);河北省教育厅科研计划资助项目(QN2019029)。

摘　　要：采用镁处理的第三代氧化物冶金技术,通过铁水预处理→转炉→LF精炼→VD精炼→CC→TMCP工艺生产70 mm厚的EH420海工钢。为了研究“焊接道次”和“线能量”对热影响区(heat-affected zone,HAZ)组织以及性能的影响,对厚板进行大线能量焊接,焊接工艺分别为170 kJ/cm线能量的三丝埋弧两道焊和250 kJ/cm线能量的三丝埋弧单道焊。结果表明,与170 kJ/cm上表面相比,170 kJ/cm T/4处由于“两道次焊接”,原奥氏体晶粒尺寸由58.60μm增加到75.22μm;M-A组元数量接近,但岛状M-A组元平均尺寸由0.96μm增加到1.26μm,条状M-A组元平均尺寸由1.89μm增加到2.44μm;恶化了低温冲击韧性,-40℃平均冲击功由205 J降低为156 J。与170 kJ/cm上表面相比,250 kJ/cm上表面由于“线能量提高”,原奥氏体晶粒尺寸由58.60μm增加到74.75μm;M-A组元数量减少,但M-A组元尺寸明显增大,岛状M-A组元平均尺寸由0.96μm增加到1.52μm,条状M-A组元平均尺寸由1.89μm增加到2.87μm,恶化了低温冲击韧性,-40℃平均冲击功由205 J降低为187 J。经过大线能量焊接后,粗晶区中存在着以MgO为核心,Ti(N,C)附着在外围的复合夹杂物,该类夹杂物能够诱导针状铁素体(intracrystalline acicular ferrite,IAF)析出,对改善冲击韧性具有帮助作用。与170 kJ/cm T/4相比,250 kJ/cm上表面M-A组元尺寸相差不大,但数量保持在较低水平,因此250 kJ/cm上表面处冲击韧性较高。相较于多道次焊接,适当提高线能量、减少焊接道次,不仅能够提高冲击韧性,还能提高焊接效率。The third generation oxide metallurgy technology with Mg treatment is adopted to produce 70 mm thick EH420 marine steel through hot metal pretreatment→converter→LF refining→VD refining→CC→TMCP process.In order to study the effect of"welding pass"and"line energy"on the microstructure and properties of heat affected zone(HAZ),thick plates were welded with large line energy.The welding processes were three wire submerged arc two pass welding with 170 kJ/cm line energy and three wire submerged arc single pass welding with 250 kJ/cm line energy.The results show that compared with the upper surface of 170 kJ/cm,the original austenite grain size at 170 kJ/cm T/4 increases from 58.60μm to 75.22μm due to"two pass welding".The number of M-A components is close,but the average size of island M-A components increases from 0.96μm to 1.26μm,and the average size of strip M-A components increases from 1.89μm to 2.44μm.The impact toughness at low temperature is deteriorated,and the average impact energy at-40℃is reduced from 205 J to 156 J.Compared with the 170 kJ/cm upper surface,the original austenite grain size on the 250 kJ/cm upper surface increased from 58.60μm to 74.75μm due to the"increase of linear energy".The number of M-A components decreased,but the size of M-A components increased significantly.The average size of island M-A components increased from 0.96μm to 1.52μm,and the average size of strip M-A components increased from 1.89μm to 2.87μm,which worsened the low-temperature impact toughness,and the average impact energy at-40℃decreased from 205 J to 187 J.After high line energy welding,there are composite inclusions in the coarse-grained region with MgO as the core and Ti(N,C)attached to the periphery.These inclusions can induce the precipitation of acicular ferrite(IAF),which is helpful to improve the impact toughness.Compared with 170 kJ/cm T/4,the size of M-A components on the upper surface of 250 kJ/cm is similar,but the number remains low,so the impact toughness on the upper surface

关 键 词：焊接工艺 镁处理 热影响区 显微组织 冲击韧性 

分 类 号：TG142.1[一般工业技术—材料科学与工程] TG44[金属学及工艺—金属材料]