Measurement of residual stresses in austenitic stainless steel weld joints using ultrasonic technique

Abstract

A methodology has been developed using a non-destructive ultrasonic technique for measuring surface/subsurface residual stresses in 7 mm thick AISI type 316LN stainless steel weld joints made by activated tungsten inert gas and multipass tungsten inert gas welding processes. Measurement of residual stresses using an ultrasonic technique is based on the effect of stresses on the propagation velocity of elastic waves. Critically refracted longitudinal L CR wave mode was employed and accurate transit time measurements were made across the weld joints. Quantitative values of the longitudinal residual stresses across the weld joints were estimated from the measured transit times and predetermined value of acoustoelastic constant for AISI type 316LN stainless steel. The nature of the residual stress profiles and their variations across the two types of weld joints were compared and interpreted.

Experimental Techniques to Investigate Residual Stress in Joints

“…Different types of wave can be employed but the commonly used technique is the longitudinal critically refracted (Lcr) wave method [4]. The Lcr wave is an acoustical wave that is excited when the angle of incidence is slightly smaller than the first critical angle, which is calculated from the Snell's law [44,68,69]. It is a bulk longitudinal wave, traveling just below the surface of the specimen.…”

“…The relation between measured travel-time change of Lcr wave and the corresponding uniaxial stress was derived by Egle and Bray [70]; with knowledge of the weld induced change in travel time and the measured acoustoelastic constant, the stress produced by the weld may be calculated [43]. The principal steps to be followed in the measurement of residual stress by ultrasonic methods are: (i) selection of weld joint or component; (ii) determination of the acoustoelastic constant (AEC) of the material using standard tensile specimen by applying varying loads; (iii) ultrasonic velocity measurements in the weld joint or component of interest and (iv) determination of residual stress using AEC [68].…”

“…The ultrasonic technique was also successfully used in the study of residual stress in dissimilar joints [41]; residual stress through the thickness of stainless steel plates with 10 mm thickness [44]; longitudinal residual stress through the thickness of aluminum plates with 8 mm thickness [45]; for assessment of surface/subsurface longitudinal residual stresses in AISI type 316LN stainless steel weld joints made by ATIG and TIG welding processes [68]; welding residual stress through the thickness of stainless steel pipe [43] and prediction of total residual stress and fusion boundary in three pass welded stainless steel plates [71].…”

Effect of Heat Input Ratio on Residual Stress in Multipass Welding Using Finite Element Method and Ultrasonic Stress Measurement

“…In fact, two different testing frequencies were employed in their work and the results were then compared. Belahcene et al [13] and Palanichamy et al [14] evaluated the residual stress in welding using L C R waves in S355 plate and in austenitic stainless steel, respectively. Furthermore, Sadeghi et al [15] evaluated longitudinal residual stress distribution through the thickness of 5086 aluminum plates made by friction stir welding.…”

Optimization of activated TIG welding parameters for improving weld joint strength of AISI 4135 PM steel by genetic algorithm and simulated annealing

“…It has been further established that by employing the A-TIG welding process, overall welding cost savings have gone up to 50 %. In A-TIG-weld joints, economic benefits in fabrication costs are achieved through the reduction in bevel preparation requirements, shortening of welding times, reduced consumption of welding filler wire, elimination of back gouging and grinding, and substantial reduction in residual stresses compared to the conventional TIG-weld joints, and the weld joints are also distortion free [15][16][17].…”