Research and Application of the Pulsed SAW Technology
|Materials Processing Engineering
|pulse automatic SAW heat input pulse frequency duty factor HAZ
The technology of automatic submerged arc welding (SAW) has been widely applied to lots of industrial fields, such as shipbuilding, energy sources, machine and so on, because it has many merits for example high productivity, high quality, flexible adjustment and good work conditions. Now SAW has been regarded as one of the welding technologies of high mechanization. When SAW is used to thick board with high heat input, the tenacity of HAZ will decline and the size of grain will increase, because of the overheating on heat-affected zone (HAZ). In order to overcome the above shortcomings, a new SAW technology, the pulsed direct current (DC) automatic SAW, will be brought forward in this paper. And a pulse controller is developed for DC automatic SAW. A micro control unit (MCU) is the core of the controller. The main functions of the pulse controller include: constant peak welding current output, constant base welding current output, peak-base welding current output and the pulse parameters monitoring with digital light-emitting diodes (LED). The results of the experiment on pulsed SAW with the pulse controller show that: the controller runs stably and correctly; the adjustment of parameters is prompt and accurate; and the human-machine interface is of amity. When pulse parameters f=15Hz, Km=15%, the peak welding current I=1000~1200A and the base welding current I=400~600A, good-shaped weld would be got. Compared with the common SAW, pulsed SAW could get deeper penetration, narrower HAZ, smaller grain and smaller coarse-grained region, and lower hardness. In conclusion, the technology of pulsed SAW put forward in this paper is of novelty thoughts; and the developed pulse controller could meet the needs of work. The research has widely prospect in application, and it has important meanings in theory and practical engineering.