Through-depth residual stress measurement of laser bent steel–titanium bimetal sheets

Abstract

Laser bending is one of the thermal forming processes which in each pass of it, the temperature of sample increases at heat-affected zone during irradiation time considerably and then it cools to near ambient temperature after passing the laser beam. Consequently, it can be predicted that the process can induce significant residual stress in the sample. In this article, laser bending process of the explosive welded steel-titanium bimetal sample was done and the through-thickness residual stress profile of it was investigated by the slitting method experimentally. The pulse-regularization approach was used to calculate the residual stress in the bimetal sample. Also, simulation of the laser bending process was performed and the numerical residual stress profile was compared with the experimental one. Furthermore, the effects of process parameters including laser power, scanning velocity and number of scanning passes on the bending angle of bimetal samples were investigated experimentally. Besides, the effect of laser bending process on the surface microhardness was studied. The results demonstrated that the laser bending process can create significant residual stress at the heataffected zone of specimen. In the residual stress profile of bimetal sample, a discontinuity was seen at the interface of the materials, as was expected. There was a good agreement between experimental and numerical results. The maximum compressive and tensile residual stresses raised by increase laser power and number of scanning passes. Both of them reduced by magnifying scanning velocity. The laser bending process can increase the surface microhardness at the heat-affected zone which can be attributed to the reduction of grain size at the heat-affected zone.

Residual stress, tensile strength, and macrostructure investigations on ultrasonic assisted friction stir welding of AA 6061-T6

“…[11][12][13] There are a number of methods which have been used for residual stress measurement of FSWed joints, in this regard, Papahn et al 14 used ultrasonic waves, Lombardi et al 15 employed neutron diffraction, and Oliveira et al 16 employed X-ray diffraction known as nondestructive techniques. Destructive techniques methods for measuring residual stresses such as slitting method, [17][18][19][20] hole drilling, 21,22 and contour method 23 have been used.…”

Recent Advances in the Laser Forming Process: A Review

“…Kotobi and Honarpisheh [32] studied the laser forming of St-Ti bilayer sheets. The induced residual stress distribution along the thickness is measured experimentally by the slitting method.…”

Optimization of the sintering temperature, cooling time and grain size parameters to reduce residual stresses of copper-aluminum functionally graded material using response surface methodology

“…There are several methods for measuring residual stresses including X-Ray, hole drilling, ring core, slitting, and contour method. 19–23 Shaw 24 investigated the effects of different material combinations including the elastic modulus, the number of layers and coefficient of thermal expansion on the residual stresses in FGMs and presented the results. Shabana and Noda 25 by using the finite element method, investigated the effect of thermal conditions on the residual stresses in the FGM plate.…”