HIGH-STRENGTH STEEL WELDING METHOD Russian patent published in 1998 - IPC

FIELD: mechanical engineering; welding. SUBSTANCE: when carrying out welding of high-strength steel, mechanical machining of weld root is done to obtain ratio of 0.4-0.6 between height of straight-line section of root zone and width of straight-line section of root zone of main weld veeing. Welding of root weld is done without heating by low alloy filler material with supply of argon maintaining ratio of product of current value and arc voltage value to welding speed within 120 and 160. Weld root is previously faced by metal providing content of carbon of 0.04-0.07%, silicon of 0.2-0.4%, manganese of 0.5-0.8%, nitrogen of 0.01-0.02%, oxygen of 0.03-0.05% and titanium of 0.0l-0.02% at temperature of heating equal to 200-300 C with high temperature tempering, lower by 40-50 C, than tempering temperature of main material. Welding of main portion of vee is carried out over diametrically opposite sectors of length equal to 1/6 of length of circumference. Welding is carried out in two steps filling the vee in height at heating temperature of 200-300 C and intermediate tempering. Heating to tempering temperature after welding and cooling after tempering are carried out at controlled preset speed as follows: heating to 550-580 C at a speed of 60-80 C/h; from 600 to 640-650 C at a speed of 30-40 C/h; cooling after tempering at a speed of 70 100 C/h within the range of 650-450 C. To provide minimum fracture of rotor axle, welding of main part of weld at a height of 1/2 of vee is carried out with heating to 200-300 C by sectors (6 pcs) in relatively opposite zones, and tempering is carried out, without cooling, at temperature by 40-50 C lower than temperature of tempering of main metal with cooling after tempering to 300 C at a speed of 60-100 C /h. After welding through entire depth of vee, tempering is carried out at temperature 20-30 C lower than temperature of tempering of rotor blanks after main thermal treatment during 12-14 h at a speed of heating to temperatures of 500-580 C at the rate of 60-80 C/h, at temperature range within 580 and 640-650 C at a speed of 30-40 C/h and cooling, after holding at temperatures in the range of 650-450 C, at a speed of 70-100 C/h. EFFECT: improved quality of weld joint. 5 dwg, 4 tbl