Selection of optimum welding conditions and evaluation of friction welded joints: Study of optimisation of welding conditions and joint performance in friction welding (2nd Report)

Summary This paper describes the possibility of optimum friction welding conditions being selected through adoption of a joining evaluation equation derived from friction welding behaviour as determined by the response surface method in welding tests of 12 mm dia. SUS304 stainless steel. Through initial analysis of the relationship between the welding behaviour and tensile strength of friction-welded joints in a multiple regression analysis, a joining evaluation equation for non-destructive estimation of joint performance is derived. The optimum welding conditions are next selected by the response surface method using the joining evaluation values determined by the joining evaluation equation as dependent variables and the friction welding conditions as independent variables. This procedure enables the optimum friction welding conditions to be determined without the need for tensile tests to be conducted. The optimum friction welding conditions determined by this procedure are friction pressure P1 = 30 MPa, upset pressure P2 = 170 MPa, friction time t1 =3.5 sec, and rotational speed N = 2425 rpm. These conditions enable a satisfactory joint efficiency ηf of 102.5% to be obtained.