METHOD OF FRICTION STIR WELDING FOR HIGH-STRENGTH THIN-SHEET OR THICK-SHEET STEEL Russian patent published in 2017 - IPC B23K20/12 

FIELD: metallurgy.

SUBSTANCE: conditions of friction stir welding correspond to the following parameters: tool rotation speed is from 100 to 1000 rpm, the tool torque is from 50 N⋅m up to 500 N⋅m, and the welding speed is from 10 mm/min to 1000 mm/min. The sensitivity index of steel for cracking Pcm calculated by the formula (1) satisfies the relation 0.18≤Pcm≤0.30. ) the value of heat input at welding HI calculated according to the formula (2) is in the range from 1.5 to 20 and satisfies formula (3) with the ratio of Pcm, and Pcm(%)=C+Si/30+(Mn+Cr+Cu)/20+Ni/Mo+60/+15V/10+5B - (1), HI(kJ/mm)=(6.28×RT×RS)/TS/1000 - (2) 1.5×10⁹×(Pcm)^13.8≤HI≤2.1×10⁸×(Pcm)^10.6 - (3).

EFFECT: method provides elimination of non-uniformity of heating and plastic flow created by mixing softened sections.

3 cl, 3 tbl, 5 dwg