Car’s Fuel Tank With Environmentally Friendly Steel Weldability Research

At present, the domestic production of more car tank is made of lead plating steel plate,There is a big pollution to the environment.Most countries have already forbids the use of lead plating steel production car tank. Our country in recent years has been studying development of tank with environmental protection plates,But haven’t reached the application.Galvanized steel is a kind of both has good corrosion resistance and good plasticity of steel grade, In automobile lightweight aspect has a great application prospect.In order to realize the application of galvanized steel sheet in the automotive fuel tank,And for welding of galvanized steel sheet provides a wider range of theoretical data and actual production experience,Based on baosteel production St16 steel substrate lead plate,galvanized tin plated steel, galvanized steel plate for the laser welding and resistance spot welding joint is studied. galvanized steel, galvanized steel plate for the laser welding and resistance spot welding joint is studied.Determine and optimize the lead plate, galvanized tin plated steel, galvanized steel, laser welding and resistance spot welding process parameters.This article through to the galvanized steel sheet of laser welding and resistance spot welding joint organization and mechanical properties of welding parameters on microstructure and mechanical properties of joint influence law get the following conclusion:(1)Thickness of 0.8 mm galvanized steel plate in the laser power is 300 W~ 600 W, the welding speed is 3 mm/s ~ 9 mm/s, from the coke quantity to-1 mm ~ 1 mm range: When the laser power is 600 W, welding speed is 6mm/s,when From coke is 0; Formation of molten nuclear, joint maximum tensile shear can reach 5.838 KN, tensile strength of 324.3 MPa;(2)Thickness of 0.8 mm galvanized steel plate welding, the welding current is 7.0 KA ~9.0 KA, electrode pressure 2.0 KN ~ 5.0 KN, welding time 8cyc~12cyc range:When the welding current is 8.5KA, time is 8cyc, electrode pressure is 3KN, Formation of molten nuclear, nuclear diameter size of 6.20 mm; Joint maximum tensile shear can reach 3.632 KN,tensile strength of 120.30 MPa;(3)Thickness of 0.8 mm the galvanized steel plate welding, the welding current is 7.0 KA~ 9.0 KA, electrode pressure is 2.0 KN ~ 5.0 KN, welding time is 8cyc ~ 12 cyc range:Welding current, welding time, electrode pressure is small(I < 8.0KA 、 T <10cyc 、 F<3KN),Spot weld mechanical properties not Enough; When the welding current, welding time,electrode pressure is big(I > 9.0KA、T > 12cyc、F > 5.0KN), Spot weld splatter is bigger, The creasing is deeper, But also can not meet the requirement of the mechanical properties.Found the spot weld the main welding defects are splash, shrinkage and fusion,can by adjusting the appropriate parameters to avoid and reduce the generation of defects;(4)Based on three kinds of steels laser welding and resistance spot welding,Microhardness test results show that the microhardness of joint distribution is uneven and the microhardness is lower than the HAZ of the microhardness of weld area, but the microhardness is higher than the welding material. Tensile test results show that,Joint fracture mode has two kinds: fracture model and the heat affected zone in combination with surface fracture mode. Through analysis of the microscopic fracture morphology we found there are a lot of toughness in fracture surface;(5)By comparing three kinds of steel, the mechanical properties of laser welding and resistance spot welding, As well as the laser welding and resistance spot welding of galvanized steel welding joint organization performance analysis, After welding of galvanized steel mechanical properties than has been used on tank galvanized tin plate, The organization is uniform, The weldability can meet the practical needs.