Study Of Weldability Of WELDOX960 High-Strength Steel

As a high strength low and alloyed structural steel, WELDOX960 is characterized by fine grain, super-metallurgical purification and homogenization, high strength and toughness, and it is widely applied in the field of mine-machine, bridge, railway and mobile crane etc. High-strength MAG-wire ED-FK 1000 is selected as consumed material according to " lower strength match" to be used in mixed gases (Ar+COi) shielded metal arc welding(GMAW). During multiplayer welding, WELDOX960 is welded with welding parameters as follow: preheat temperature is 75 ℃, heat input is 1. 0~1. 2KJ/mm, Interpass temperature is 80~85℃.Mechanical tests (tensile test, bending test and impact test) and crack tests (Y-groove and CTS cracking test, peak hardness of HAZ test) were carried out to study on its weldability; and microstructures of weld metal, fusion zone, HAZ and fractography were investigated by means of light microscopy and SEM; the effect of processing factors and microstructures of welding joint on strength and toughness of welding joint was analyzed.Experimental results indicated that WELDOX960 has a good capacity of resisting cool cracking and hot cracking with suitable welding parameters. GET is a key factor to the performance of joint. With a small value of GET, the joint will be apt to get cracking due to fast cooling and big temperature grade while a big value of GET will damage the performance of joint sharply due to coarse grain and welding interstress. Microanalysis indicated that granular bainite and low-carbon martensite were found in weld and HAZ,which contributed to high strength and toughness of joint. So GET must be limited in the range of 1. 0~1. 2 KJ/mm to make sure that granular bainite and low-carbon martensite be acquired in weld.