Studay On Dissimilar Metal Joining Of Aluminum To Steel By Pulsed DE-GMAW

More and more attentions are paid to the environmental protection nowadays. Aiming atthe energy conservation and emission reduction,"Aluminum+steel" structures became thefocus of attention. But, because of the large thermal difference between aluminum and steel,hot crack defects often appear in the welding process. As well As the IMC, which is harmfulFor the joint performance.In this papper, a new low-cost arc welding method was proposedfor joining of aluminum and steel, which is named Pulsed DE-GMAW. With this method injoining of aluminum and steel, the production of inter-metallic compounds could becontrolled by controlling the welding heat input suitablely.Frist, Pulsed DE-GMAW experiments were carried out to joint aluminum wire ER5356to zinc coated steel, and obtained symmetrical weld joint. Study on the weld section usingOM、XRD and EPMA, the results show that Fe and Al atoms diffused sufficiently inintermetallic formation. The IMC is compose of Fe2Al5Zn0.4, rich-zinc zone is located in theedge of weld metal exists, composed of α-Al and β-Zn solid solution.Then, the thermal cycle curves for Pulsed DE-GMAW were measured and influence lawof different bypass parameters to thermal cycle curve and the thickness of the IMC wasstudied.Measured the thermal circling curve in different parameters of Pulsed DE-GMAWand CMT, to fing out the better way for the joining.The results show that: CMT can reducethe welding heat-input while Pulsed DE-GMAW also control the heat-input by increasebypass current, to realize the joining.Lap welding process optimization was done for Pulsed DE-GMAW for joiningaluminum to galvanized steel, and mechanical properties test was carried out for lap jointspecimens of aluminum alloy and galvanized steel. Studied the influence of bypass arcparameters and weld geometry parameters on mechanical properties of lap joint. The resultsshow that the maximum tensile strength is up to186.73MPa, about88.5%of the base metalstrength.