Determination of Robot Welding Process for Medium Thick Q960 Steel Plate for Hydraulic Supports

The welding thermal simulation test was conducted on medium thick Q960 steel plate for hydraulic supports. The microstructure and hardness of the coarse-grained heat-affected zone under different cooling rates (0.5-100℃·s^-1) were analyzed. The robot welding process was determined by Tekken test and welded joint mechanical performance tests. The results show that the simulated hardness of coarse-grained heat-affected zone could be stabilized below 420 HV when the cooling rate was lower than 80℃·s^-1, namely the welding heat input was greater than 6.5 kJ·cm^-1 under the preheated temperature of 100℃. The Q960 steel plate joint welded by robot welding had excellent cold crack resistance sensitivity under the welding heat input of 13.95 kJ·cm^-1 and the preheated temperature of 100℃. The properties of robot welding Q960 steel plate joint could meet the standard requirements within the welding heat input of 13.02-15.18 kJ·cm^-1 with ER96-G welding wire. The recommended welding parameters for robot welding were listed as follows:preheating at 100℃, welding current of 460 A, voltage of 33 V, welding speed of 60 cm·min^-1 and wire feed rate of 8.5 m·min^-1, and the welding deposition rate could reach 8 kg·h^-1.