超大电流焊接时药皮不易脱落的不锈钢焊条

Stainless steel electrodes with un-released coating for ultra high current welding

采用平板堆焊、工艺参数实测对比、宏观观测分析等试验方法,研究超大电流焊接时不锈钢焊条药皮与焊芯间形成的熔化组织特性、药皮温升脱落机理,以及控制药皮脱落原理,实测了专用焊条的药皮抗脱落性和综合工艺性等指标。结果表明,新型专用不锈钢焊条在超大电流下焊接时,后段焊条药皮部分区域被熔化,生成的蜂窝状组织与焊芯氧化层形成牢固结合层。随焊接电流超大化增加,新型专用A焊条药皮抗脱落性优于对比用C焊条,关键原因是前者药皮在高温时形成的蜂窝状组织在起作用。超大电流焊接时,不锈钢焊条药皮脱落受三个条件的控制,一是焊芯的电阻大、温升高、线膨胀系数大;二是药皮的高温塑性变形性能差;三是焊芯与药皮间的结合层过早被分离。上述条件中,一是药皮脱落的必要条件,二和三则是充分条件,二者缺一不可。基于文中提出的控制药皮温升脱落对策,研制的"在特大电流下焊接时药皮不脱落的专用不锈钢焊条",在"苛刻要求"产品中应用获得了满意的使用效果。

The characteristics of molten structure between coatings and core wire in ultra high current welding process,and the mechanism of stainless steel electrodes coating releasing as increasing temperature,and the principle to control the coating releasing were studied by the bead-on -plate test,comparison of welding parameters,and the observation and analyses of test phenomenon of welding.The anti-removing ability of coating for special electrode and its comprehensive usability were measured.The results show that the firm combination by oxide of core wire and honeycombed structure of coating is formed when the new special stainless steel electrode was used with ultra high welding current.The new special stainless steel electrode A is superior to C in the anti-releasing ability of coating as the welding current being increasing due to the formation of honeycombed structure during the elevated temperature.There are three conditions that contribute the stainless steel electrode covering to release with the ultra high welding current:1) higher resistance,elevated temperature and higher linear expansion coefficient of core wire;2) degraded plastic deformation during high temperature of coating;and 3) prematurely separation between core wire and coating.The first one is the necessary condition for coating releasing,and the second & the third are the sufficient condition.The satisfactory results in the application of the special stainless steel electrodes developed based on the principle to control coating releasing,with un-released coatings under the condition of ultra high welding current were obtained.