Relieving Welding Residual Stress by Applying Vibratory Weld Conditioning

Heat input of welding causes temperature gradient in the steel structure. After welding and along with temperature cooling down, residual stresses appear around the welding zone, cause the welding deformation. Residual stresses are a result of the temperature gradient, restraint intensity and the dependency of material properties on the temperature, such as yield strength, elasticity modulus, and thermal expansion coefficient. Vibratory weld conditioning is a new technology which vibrates the workpiece while welding by vibrator. Its main purpose is to refine grain, relieve residual stress, minish welding deformation and improve the properties of welded joint. Firstly, electro-slag weld was done in the two kinds of vibration condition: 0.3g and 0.6g. Then, the distribution of welding residual stress was measured with blind hole-drilling method. Results show vibratory weld conditioning may relief welding residual stress greatly and Gmax is less than 12sigmas. From metallograph, vibratory weld conditioning can refine the grain effectively. The grain size of 0.6g was smaller than that of 0.3g. While from the measuring values of residual stress, 0.6g's are higher than that of 0.3g's.And also conclude that after finishing welding continuing vibrating a period to increase the inputting energy is benefit to the relief of welding residual stress.