According to the technical requirements for the manufacture of steel for the first mine car of maximum load in China and characteristics of high strength copper-bearing [w（Cu）=1%

1

.3%] constructional steel（WA710）

applied experimental analysis of experiments of welding crack resistance and gas protection welding technology under different temperature conditions is carried out.The experimental results of crack resistance（small iron test） show that:under environment of room temperature and low temperature（-5 ℃） and environment relative humidity being 80%

it’s allowed not to carry out preheating welding for such steel. Experimental results of gas protection welding process evaluation show that:with the use of protective gas φ（Ar）80%+φ（CO

2

）20% and WER70-NH（patented） wire

the mechanical properties of welded joints meet the technical requirements for the manufacture of China’s first mining vehicle of maximum load（363 tons）.