Experimental and numerical investigation of through-thickness residual stress of laser-bent Ti samples

Abstract

One of the important parameters that can influence on performance of a part and its life is residual stress. All manufacturing processes can create residual stress in different ranges. Laser bending is one of the thermoforming processes that has been used in different industries. The aim of this study is investigation of through-thickness residual stress profile of Grade 2 titanium samples that were subjected to laser bending process. Slitting method was used to measure the residual stress profile experimentally. Both series expansion and pulse-regularization methods that are common computational techniques in the slitting method were employed to calculate the residual stress. Besides, finite element simulation of the laser bending process was done to study the through-depth residual stress distribution numerically. The results of two computational techniques were compared to each other and with the finite element method results. Furthermore, the effect of laser bending process on surface roughness and microhardness of the samples at the heat-affected zone was investigated. The results showed that laser bending process can induce considerable residual stress in the heataffected zone of the part. Comparing the experimental and finite element method results showed good agreement between them. In comparison with the control sample, both surface roughness and microhardness of the samples increased after the laser bending process.

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.…”

Investigation of shot blasting and thermal stress relieving processes on residual stresses and corrosion behavior of X60 steel gas pipelines

“…There are many methods such as slitting [11][12][13], incremental hole-drilling [14,15], ring core method [16] and cross cutting methods [17,18] in order to measure the residual stress, and among them contour method is one of those methods which measures residual stress by surface contour. Furthermore, lots of studies have been carried out related to residual stress using the contour method.…”

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

“…9 This method was employed to study residual stresses of different materials and manufacturing processes. 11,12,[14][15][16][17][18][19][20][21] Laser bending is a thermal forming process that can be used in different industrial applications. Temperature gradient mechanism (TGM) is one of the common mechanisms of laser forming.…”

“…22,23 A schematic of laser bending process is shown in Figure 2. 21 Kotobi and Honarpisheh 21 investigated throughdepth residual stress distribution of commercially pure Grade-2 titanium parts which were subjected to laser bending. Laser bending of AISI304 stainless steel sheet under TGM was studied by Maji et al 24 numerically and experimentally.…”

“…A schematic of laser bending process. 21 investigate the through-thickness residual stress at the heat-affected zone (HAZ) numerically, finite element simulation of the laser bending process was performed. Furthermore, the effects of laser power, scanning velocity and number of scanning passes on the bending angle were analyzed experimentally.…”