Influence of ultrasound on changes in a structurally stressed state of baths formed by laser melting

A study was made of the influence of ultrasonic vibrations injected into a laser melt on changes in a structurally stressed state formed as a result of fast cooling of the surface of T1 high-speed tool steel. Injection of ultrasound into a laser melt helped to complete structural — phase transformations. When pulsed laser radiation was used, ultrasound reduced the residual tensile stresses and could reverse their sign, whereas in the case of cw laser radiation, injection of ultrasound resulted only in the formation of compressive residual stresses. These features were evidence of the promising nature of a combined laser — ultrasound source for crack-free welding.