Research On Welding Of 150mm Thickness EN 10225 S3Z-S420 G2 Quenched Low Carbon & High Strength Steel

This paper introduces the welding project background, welding technology process background, welding Specifications, and material standards. Discussion about three kinds of welding positions in 1G,2G &3G, and three kinds of welding methods in 111—SMAW, 112-SMAW& 136-CO2 FCAW, chemical material of 150mm thickness EN 10225 S3Z S420 Mpa group 2 quenched steel plate, Carbon Equivalent Value(CE), welding geometry joint design, then establish design of a V-groove weld in 111-SMAW & 136-CO2 FCAW methods, and a double V-groove (X-groove) weld in 112-SAW welding, and establish welding equipments. According to analysis, make a selection on consumable with the diffusible hydrogen content of less than 5 ml/100g deposited metal or a moisture content of electrode covering of 0.2% maximum, then analysis from carbon chemical composition in material and carbon equivalent value (CE) which those effect on hydrogen crackle, and analysis the welding thermodynamic factors, confirm the steel plate heated by major electrode-heat and together with gas touch heated if necessary. According to the analysis, confirm the pre-heat temperature between 125℃and150℃, and inter-pass temperature between 125℃and 250℃, heat input parameters like the voltage and current in different positions and welding speeds , multi-pileup, welding temperature trend and heat treatment after welding effect on welding technology, then validate the pre-parameter of welding, and take into the welding test.After monitoring the pre- parameter and welding test in process, compare to the three kinds of welding methods, high thickness FCAW sample is easily affected on welding speeds and heat input, especially for the root welding of different melt material SMAW and some welding defects, then all those factors lead to welding crackles, and especially failed in the center of the root welding, which is a double V-groove joint weld.. After the test of the samples, its show that there are too many factors effect on root of EN 10225 S420 material in the double V-groove joint center weld, it easily lead to weld crackles, then the mechanical characteristics test and Charpy-V tough test are not so good. The action should be taken a higher heat input. The inter-pass welding temperature within in 230℃is better function in multi-layer welding, and the covering welding layer take a good tempering function for covered layer and prevention the more crystal spanning. It is obviously that it makes improvement on the overall mechanical characteristics, strengthens and decreased the welding grips. And the capping parameters take obviously function on the overall mechanical characteristics, the capping dealing technology can take a good function to decreasing the weld stress and remind stress, and decreasing the risk of weld defects. Then, according to welded basic material of the carbon equivalent CE value, can issue same material covered CE values between 0.40±0.03 in the same structural welding procedures.