The Effect of Laser Welding on the Tensile Strength and Radiographic Analysis of Co-Cr Repaired Joints

Abstract

Aims:To evaluate the effect of laser welding and arc welding on the ultimate tensile strength, radiographic appearance of the joints, and microscopic porosities in the fractographs. Four joining methods have been used, laser welding, and arc welding using three types of electrodes (iron, stainless steel, and brass). Effect of surface roughness on the aforementioned properties was evaluated. Materials and Methods: Three specimens as-cast control group, seventy two specimens were treated by polishing, laser, and sandblasting, and joined with the four joining methods. Joints examined by radiograph and porosities were measured by Dimax software program, their ultimate tensile strength, and strain was tested, and the microscopic porosities in the fractographs were measured using AutoCAD software program. Three cobalt chromium bars from the third group were joined to three stainless steel bars from the fourth group of the same diameter to test the ultimate tensile strength, and strain of the dissimilar alloys. Results: Laser welded and brass soldered joints had significantly lower ultimate tensile strength and strain when compared to the control group, while the iron, and stainless steel soldered joints had insignificant differences in the ultimate tensile strength and strain when compared to the control group. Results shown that the iron and stainless steel soldered samples fractured in the heat affected zone while the brass soldered and laser welded samples fractured in the weld zone. The iron and stainless steel soldered joints had superior mechanical properties when compared with the control group. Laser welding of dissimilar alloys had the lowest mechanical properties among all techniques. Conclusions: revealed that laser welding was the most precise technique used in the current study. Weld fractures shown less tensile strength average and more brittle behavior. Radiographic properties had no influence on the mechanical properties of the joints.