应用稀土氧化物冶金技术改善高强钢焊接性能  

Enhanced Welding Properties of High Strength Steel via Rare Earth Oxide Metallurgy Technology

作　　者：陆斌 陈芙蓉[1] 智建国[2,3] 耿如明[4] LU Bin;CHEN Furong;ZHI Jianguo;GENG Ruming(School of Materials Science and Engineering,Inmer Mongolia University of Technology,Hohhot 010051,China;Inner Mongolia Baotou Steel Union Co.,Ltd.,Baotou 014010,China;Inmer Mongolia Enterprise Key Laboratory of RareEarth Steel Products Research and Development,Baotou 014010,China;State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing.Beijing 100083,China)

机构地区：[1]内蒙古工业大学材料科学与工程学院,呼和浩特010051 [2]内蒙古包钢钢联股份有限公司,包头014010 [3]内蒙古自治区稀土钢产品研发企业重点实验室,包头014010 [4]北京科技大学钢铁冶金新技术国家重点实验室,北京100083

出　　处：《金属学报》2020年第9期1206-1216,共11页Acta Metallurgica Sinica

摘　　要：在高强钢中加入5×10-6和23×10-6稀土Ce,研究了Ce对焊接热影响区冲击韧性、微观组织、原奥氏体晶粒以及焊接接头断口形貌的影响与机理。钢中含Ce量为5×10-6时,能在镁铝夹杂物外围生成少量CeAlO3夹杂物,但不能完全改性镁铝夹杂物,当Ce添加量达到23×10-6后,Ce能够完全改性MgO-Al2O3尖晶石,生成(CeCa)S+MgO-Al2O3+MnS稀土夹杂物。对含有Ce的高强钢板进行模拟焊接,结果表明,在4组不同焊接热输入条件下,钢中加入23×10-6Ce后,比钢中加入5×10-6Ce的钢焊接热影响区的Charpy冲击功有所提高。微观组织分析发现,23×10-6Ce含量的高强钢试样焊接热影响区断口形貌呈现韧窝状,韧性更好;当热输入从25 kJ/cm逐步提高到100 kJ/cm时,含5×10-6Ce的高强钢热影响区原奥氏体晶粒平均尺寸增加了75.6%;含23×10-6Ce的高强钢的原奥氏体晶粒平均尺寸增加了52.4%,即钢中Ce含量的增加抑制了焊接热影响区原奥氏体晶粒的长大。通过微观组织分析对比,说明稀土Ce在高强钢中起到了延迟焊接热影响区上贝氏体组织形成的作用,同时抑制焊接过程中原奥氏体晶粒的长大。利用高温共聚焦显微镜观察到了稀土夹杂物钉扎于原奥氏体晶界,抑制焊接过程中晶粒的长大,验证了稀土Ce对高强钢焊接热影响区性能改善的机理。本工作表明应用稀土氧化物冶金可以改善稀土高强钢的焊接性能。With the increase of the strength of steel plate, the welding performance of the steel decreases sharply and the welding crack susceptibility increases. The properties of welding heat-affected zone of high strength steel lower with increasing the welding heat input. The present work aims to improve the toughness of welding heat-affected zone by rare earth oxide metallurgy technology. The effect of 5×10-6 and 23×10-6 rare earth Ce on the impact toughness, microstructure, austenite grains of heataffected zone and fracture morphology of welded joint were studied. When the steel contains 5×10-6 rare earth Ce, the inclusions are MgO-Al2O3 spinels surrounded with a small amount of CeAlO3 inclusions. In the case of the steel with 23×10-6 Ce, Ce can completely modify MgO-Al2O3 inclusions, resulting in the formation of(Ce Ca)S+MgO-Al2O3+MnS complex inclusions. The simulation welding of high strength steel was performed. The results show that the Charpy impact energy of heat-affected zone of the steel with 23×10-6 Ce is higher at four different heat inputs, in comparison with the steel with 5×10-6 Ce. The microstructure analysis shows that the fracture morphology of heat-affected zone of the steel with 23×10-6 Ce appears dimples, which is an indication of a higher toughness. With increasing the heat input from 25 kJ/cm to 100 kJ/cm, the average grain size of the original austenite in the heat-affected zones of the steels with 5×10-6 Ce and 23×10-6 Ce was increased by 75.6% and 52.4%, respectively. It indicates that the growth of the original austenite grain during welding is suppressed with increasing the Ce content in the steel. Comparison of the microstructure shows that rare earth Ce can delay the formation of upper bainite structure in the heat-affected zone. Through the high temperature confocal microscope, it was observed that the rare earth inclusions pinned on the original austenite grain boundary, which can effectively restrain the grain growth during the welding process. It provides an evidence showing t

关 键 词：高强钢 热影响区 氧化物冶金 稀土 

分 类 号：TG457.11[金属学及工艺—焊接]