N和O元素引入对GPCA-TIG焊焊缝冲击韧性的影响  

Effects of introductions of oxygen and nitrogen elements on impact toughness of gas pool coupled activating TIG weld metal

作　　者：黄勇[1] 郭卫[1] 王艳磊[1] HUANG Yong;GUO Wei;WANG Yanlei(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology,Lanzhou,730050,China)

机构地区：[1]兰州理工大学,省部共建有色金属先进加工与再利用国家重点实验室,兰州730050

出　　处：《焊接学报》2022年第5期83-89,I0008,I0009,共9页Transactions of The China Welding Institution

基　　金：国家自然科学基金资助项目(51265029)。

摘　　要：通过外层气体引入O和N元素,气体熔池耦合活性TIG焊(gas pool coupled activating TIG welding)可以实现深熔深、高质量和连续焊接.为了研究清楚O和N元素引入对焊缝冲击韧性的影响规律和机理,针对SUS304不锈钢分别测试了外层气体为O_(2),N_(2)和O_(2)+N_(2)时的焊缝低温冲击韧性,并从焊缝组织成分、析出物种类及形态以及晶粒取向等方面分析了其影响机理.结果表明,外层气体引入对GPCA-TIG焊焊缝低温冲击韧性影响较大,单独引入O_(2)时将明显降低,单独引入N_(2)时降低较少,而同时引入O_(2)和N_(2)将增加焊缝金属低温冲击韧性.O和N元素同时引入增强GPCA-TIG焊缝金属低温冲击韧性的机理主要在于:焊缝组织较细,金属中的O和N元素含量和所形成的非金属夹杂物的增加程度和铁素体数量的下降程度都较少,却增加了奥氏体晶粒大角度晶界数量以及铁素体晶粒与奥氏体晶粒之间位向关系的匹配性,从而使得裂纹不易扩展,韧性增强.Through introducing oxygen and nitrogen elements from the outer gas of gas pool coupled activating TIG(GPCA-TIG)welding,deep penetration,high quantity and continuous welding are accessible.In order to obtain the dependence and mechanism of weld metal impact toughness on the introduced oxygen and nitrogen elements,GPCA-TIG welding for stainless steel SUS304 with the outer gases oxygen,nitrogen and nitrogen-oxygen gas mixture respectively were performed to gauge low temperature impact toughness of the weld metal.Then,a series of testing experiments including weld microstructure and chemical composition,nonmetallic inclusion and grain orientation were conducted.The results reveal that,the introduction of oxygen makes the low temperature impact toughness of weld metal decease obviously,nitrogen decease a little,while the low temperature impact toughness of weld metal can be increased a little conversely when oxygen and nitrogen are synchronously introduced.The main mechanism is proven that the synchronous introduction of oxygen and nitrogen elements leads to fine grain of weld microstructure,less increases of the contents of oxygen and nitrogen elements and the nonmetallic inclusions,much decrease of ferrite number in weld metal.Meanwhile,the high angle grain boundary number in austenite crystal and the matching property of grain orientations between ferrite and austenite are improved.All of these result in difficult cracking propagation and higher toughness.

关 键 词：不锈钢 O元素 N元素 气体熔池耦合活性TIG焊 冲击韧性 

分 类 号：TG401[金属学及工艺—焊接]