1Cr12Ni3MoVN (S/SJ2) is China from British Rawls Royce imported materials. Mainly used in the manufacture of the British "Spey MK202 engine high temperature parts. Have the strength, toughness and good oxidation resistance of the material, has been used to manufacture high pressure vane, high pressure air inlet box, compressor disk, compressor blade, turbine shaft and other parts in a variety of aircraft engine.
Martensitic stainless steel in the weld ductility, toughness, and strength and hardness increased, residual stress, coupled with the hardening of the material itself is large, easily lead to the emergence of cold cracks. Therefore, it is necessary to study the welding process and welding mechanism of this kind of alloy. Researchers in Nanchang Aviation University School of aeronautical manufacturing engineering are using TIG welding of 2.5mm thick 1Cr12Ni3MoVN martensitic stainless steel plate, welding the influences of process parameters on the properties of welded joint research, optimization of process parameters. This study will be helpful to reduce the cost and difficulty of fabrication of the material, and to extend the application of 1Cr12Ni3MoVN alloy.
Test material for 1Cr12Ni3MoVN martensitic stainless steel plate, conditioning state supply, thickness of 2.5mm, the size of 100mm * 300mm. In order to ensure uniform martensite structure, and in the adjustment of the composition does not appear delta phase, it must be used to balance the austenite element, that is, there should be an appropriate amount of C, Mn, Ni, N. Therefore, the ER410NiMo wire with high temperature resistance and oxidation resistance is chosen as the filling material, and the diameter of the welding wire is 2.0mm. Test protection gas.
Test welding equipment for Lincoln SQUAREWAVETIG-355, water-cooled gun. The experiment adopts the automatic wire filling TIG welding, the joint form is butt welding, the groove of the joint is in the form of the first groove, and the one side welding double side forming. In order to better protect the weld, the welding torch welding test before 5S protecting gas, post weld 5S die.
The influence of welding current and welding speed on the joint is considered. The DC welding current through the pre experiment to determine the range of welding parameters: welding current of 80 ~ 130A, 8 ~ 16L/min gas flow rate, arc length of 1 ~ 3mm, the nozzle and the workpiece distance is 10 ~ 12mm, the butt joint gap is 0.1 ~ 0.5mm. Welding speed was 0.95mm/s and 2.33mm/s, respectively. The results are as follows:
(1) using ER410NiMo welding wire of 2.5mm1Cr12Ni3MoVN martensitic stainless steel plate, the welding current is 96A, the welding speed is 0.95mm/s, wire speed as 1mm/s parameters by the mechanical properties of the joints, the tensile strength reached 989MPa, and parent material.
(2) the tempering zone of 1Cr12Ni3MoVN martensitic stainless steel joint heat affected zone was softened, the strength and hardness were lower than that of base metal and weld. The highest hardness is located at the weld, about 611HV; the lowest hardness in the heat affected zone of tempering zone, about 292HV; the hardness of the base metal is about 321HV.
(3) the weld microstructure of lath martensite as cast and quenched zone microstructure in the heat affected zone is coarse lath martensite, incomplete quenched zone is lath martensite and ferrite, tempering sorbite zone for high temperature tempering, microstructure of parent material is tempering sorbite.
