电弧增材制造钛合金界面处残余应力及其影响

A Ti-6Al-4V wall was fabricated by wire+arc additive manufacturing (WAAM) on the basis of substrate alloy. Residual stress in the WAAM-substrate wall was measured by a contour method, revealing there are considerable residual stresses. A finite element model was developed to simulate stress releasing in the cutting processing of the compact tension (C(T)) specimen from the wall. The calculated residual stress retained in the C(T) specimen is in good agreement with the measurement result obtained by the contour method. Residual stress evolution and its effect on the crack propagation behavior at the WAAM/substrate interface were estimated by the developed finite element model. Experimental and numerical analyses show that residual stress distributions are quite different in Type A and C specimens. For Type A specimen (notch located in the substrate), the compression residual stress area is close to the notch, whereas for the Type C specimen (notch located in the WAAM alloy), the compression residual stress area is far away from the notch. Residual stresses have a little effect on the fatigue crack growth life of Type A specimen since most of them are released after the crack quickly enters and goes through the compression area. However, residual stresses decrease slightly with the crack growth at a long period for Type C specimen, which results in a high stress intensity factor and shortens the fatigue crack growth life.