Tensile and Bending Restraint in Butt Welding of 80kg/mm² Class High Strength Steel

Abstract

In the present paper, the behaviours of restraint force and bending moment and distortion in three-pass welding of medium thick (12.7 mm) HT80 steel plate are investigated experimentally using H-type restrained specimens. The main results are as follows:
According as the thermal contraction of weld occurs after welding the first pass, restraint tensile force and bending moment that bends the restraint plates convex upward grow due to nonelastic shrinkage caused in the weld zone and its downward eccentricity about the neutral plane of base plate, though their signs as well as magitudes are changed temporarily when the transformation of austenite accompanying expansion takes place in the weld zone.
In each welding of the second and third passes, the initial distortion and restraint force are almost extinguished by the heating, and in the cooling processes the restraint force and bending moment are reproduced in accordance with the magnitude and eccentricity of the shrinkage and expansion.
The amount of transverse inherent shrinkage in the weld zone after welding each pass is approximated by subtracting the expansion mostly referable to the phase transformation from the calculated value of plastic contraction induced by constraining the thermal expansion of weld.
The experimental values of intensity of tensile restraint for the weld-joints are scarcely affected by their angular distortions.