导　　师： 樊丁;张瑞华

学科专业： 080503

授予学位： 硕士

作　　者： ;

机构地区： 兰州理工大学

摘　　要： 近年来,高效节能的新型焊接方法成为国际焊接领域研究的热门课题之一。目前对活性焊接方法的研究表明,对于碳钢、不锈钢等钢材而言,活性元素氧可改变钢材熔池表面张力温度系数,从而使熔深增加。通过改变活性元素的引入方式,本文提出一种新的活性焊接法--激光辅助活性TIG焊,即LA-TIG焊/(Laser assisted Activating TIG Welding/)。该方法采用辅助激光在焊件表面制造一道很薄的氧化层取代活性剂的涂敷,然后进行TIG焊,同样可使焊缝熔深显著增加。 以SUS304奥氏体不锈钢/(0Cr18Ni9/)和Q235低碳钢作为对象,研究了主要工艺参数对激光辅助活性TIG焊焊缝熔深和熔宽的影响,并对不锈钢熔深增加机理进行了分析。 通过金相组织观察分析了氧化层对LA-TIG焊缝显微组织的影响,并通过力学性能等测试分析了LA-TIG焊缝的低温冲击韧性、抗腐蚀性能和硬度的变化。通过对焊缝进行化学成分分析,对比研究了传统TIG焊与LA-TIG焊缝化学成分的变化,从而进一步说明氧化层对LA-TIG焊焊缝性能的影响。试验结果表明,LA-TIG焊缝各项性能和化学成分与传统TIG焊很接近,可见,氧化层对焊缝组织和性能的影响不大。 在熔深增加机理方面,首先通过对电弧形态和焊接电压的分析,研究了电弧收缩对熔深增加的影响,其次,通过XPS测试研究了氧化层中的氧化物对表面张力的影响机理,并通过SEM和EDS分析研究了氧在焊缝熔池中的含量分布情况。通过计算氧化层中的含氧量,确定了氧含量与焊缝熔深的关系。结果表明,电弧收缩不是熔深增加的主要原因,氧作为活性元素可改变钢材熔池表面张力温度系数是焊缝熔深增加的主要机理。同时,氧在焊缝中的含量较低,主要存在于焊缝表面,进一步说明,氧化层对焊缝性能的影响很小。 LA-TIG焊所使用的活性剂中氧是以化合物的形式存在,氧对熔� Recently,study of high efficiency and energy saving new welding processes has become one of hot topic of the international welding fields.Recent study of activating welding showed that,the temperature coefficient of surface tension was changed by Oxygen was the main mechanism of increasing weld penetration for mild steel,stainless steel and other steel products.A new activating welding process has been put forward by changing the way of adding activating elements-LA-TIG welding/(Laser assisted Activating TIG Welding/).Before the TIG welding,using the assisted Laser to prepare a thin oxide layer instead of coating activating flux,the weld penetration also can increase. Taking the Q235 low-carbon and SUS304 austenitic stainless steel as investigation object,the influence of welding conditions of LA-TIG on welding penetration and welding width was investigated. The influence of oxide layer on weld microstructure was studied by metallographic analysis,and the low-temperature impact toughness,corrosion resistance and hardness were also tested.Through the weld chemical composition analysis,the chemical composition differences between the traditional TIG welding and LA-TIG welding were studied.The results showed that the mechanical properties and chemical compositions of LA-TIG welding were very close to traditional TIG welding,and the oxide layer had little effect on the microstructure and performance of LA- TIG weld. In terms of the mechanism of increasing weld depth,first,the effect of arc contraction on weld depth was studied through the analysis of arc shape and welding voltage.Second,the effect of oxides in oxide layer on surface tension was studied by XPS test.Third,the content distribution of oxygen in the welding pool was tested by SEM and EDS analysis.At last,the relationship between the weld penetration and oxygen content was studied by calculating the oxygen content of the surface of welding pool.The results showed that arc contraction was not the main reason for increasing weld penetration,th

关 键 词： 焊 激光 氧 熔深 表面张力温度系数

领　　域： [金属学及工艺]