外伸型管板全位置TIG打底自熔工艺研究

Study on all position TIG root self-fusion parameter of extensional tube-tubesheet joint

采用全位置TIG管板焊机对坡口深度2 mm、角度45°、管子外伸5 mm的碳钢管板接头进行了焊接,在此基础上设计并实施了5组不同的打底自熔焊接试验。结果表明,随着焊接速度、电弧长度、侧壁距离的递减以及脉冲频率的递增,打底焊缝三点钟位置的熔深逐渐增加,其中以降低焊接速度效果最为明显。但是随着峰值电流的递增熔深先递增,达到峰值后由于管壁大量熔化熔深又逐渐减小。当峰值电流185~190 A、基值电流78~80 A、占空比25%、脉冲频率2.5 Hz、电弧长度1.2~1.4 mm、钨极离管壁距离1.2~1.4 mm、焊接速度55 mm/min时,全位置焊接可以实现根部完全焊透。

All position TIG tube-tubesheet welding machine is used to weld the carbon steel tube sheet joints with 2 mm groove depth,45 degree angle and 5 mm tube extension.On this basis,five groups of different self-fusion experiments were designed and implemented.The results show that with the decrease of welding speed,arc length,sidewall distance and the increase of pulse frequency,the penetration of root welding at 3 o'clock position increases gradually,and the effect of reducing welding speed is most obvious.However,with the increase of pulse current,the penetration increases firstly and then decreases due to the tube wall’s melting.When pulse current range from 185 A to 190 A,base current range from 78 A to 80 A,duty cycle 25%,pulse frequency 2.5 Hz,arc length range from 1.2 mm to 1.4 mm,the distance from electrode to tube wall range from 1.2 mm to 1.4 mm,and welding speed 55 mm/min,the complete root penetration can be achieved.