大型LNG储罐用9Ni钢焊接工艺与机理分析研究.doc

摘要 PAGE LIV 大型LNG储罐用9Ni钢焊接工艺与机理研究 摘 要 本文针对大型液化天然气（LNG）储罐对9Ni钢的焊接需求，系统研究了9Ni钢的焊条电弧焊（SMAW）、钨极氩弧焊（GTAW）和埋弧焊（SAW）的焊接工艺与机理。利用光学显微镜、扫描电镜及能谱分析、强度测试和硬度测试等方法，分别研究了9Ni钢焊接接头的界面显微组织和力学性能。通过研究工艺参数对接头微观组织和力学性能的影响，优化了焊接工艺，阐明了接头不同特征区域的断口特性。通过对比分析三种焊接方法在大型LNG储罐生产中的适用性，确定底板和壁板不同位置焊缝需要选择的最佳焊接方法。通过对比分析三种焊接方法可知：大型LNG储罐的现场焊接方法最好采用以上三种方法的组合，其中，底板的平位置焊缝最好采用焊条电弧焊或钨极氩弧焊方法；壁板的横位置焊缝最好采用埋弧焊方法；壁板的立位置焊缝最好采用焊条电弧焊或钨极氩弧焊方法的多层多道焊；而底板与壁板的接缝是平角缝，最好采用埋弧焊方法。 关键词：9Ni钢；焊接方法；界面结构；力学性能 Large LNG tanks with steel welding and 9 Ni mechanism research ABSTRACT This article in view of the large liquefied natural gas (LNG) of 9 Ni tanks of steel welding demand, the systematic study of the steel electrode 9 Ni electric arc welding (SMAW), tungsten extremely argon arc welding (GTAW) and submerged arc welding (SAW) of the welding process and mechanism. Use of optical microscopy, scanning electron microscope and energy spectrum analysis, strength and hardness testing methods of test, are studied and Ni steel welding joint microstructure of interface and mechanical properties. Through the research process parameters on the joint microstructure and mechanical properties of the influence, the optimization of welding technology, and expounds the characteristics of different region joint fracture characteristics. Through the comparison and analysis of the three welding method in large LNG tanks the applicability of production, to determine the bottom and wall plate weld need to choose different positions of the best welding method. Through the comparison and analysis of the three kinds of welding method it is to know that the large LNG storage tank welding method had better use the combination of three kinds of methods, among them, the flat bottom position had better use the electric arc welding electrode or tungsten extremely argon arc welding methods; Wall plate of horizontal position weld had better use submerged arc welding methods; Wall plate made of weld had better use electrode position electric arc welding or tun