Residual Stresses In Longitudinal Direction Research Articles

Residual Stress Relaxation of Shot-Peened Deformation Surface Layer on Duplex Stainless Steel Under Applied Loading

The relaxation of residual stress in shot-peened surface layer of duplex stainless steel S32205 under static and cyclic loading was investigated. The results reveal that the compressive residual stress is relaxed under applied tensile stress. The relaxation of residual stress in longitudinal direction is more obvious than that in transverse direction in both austenite and ferrite. When the applied stress is beyond the yield strength of the materials, the relaxation of the residual stress becomes drastic. Under cyclic loading, the residual stress relaxation occurs fast in the first few cycles, it then becomes stable gradually. A model was used to quantitatively calculate the residual stress under cyclic loading with different applied tensile stresses. The relaxation behavior is determined by the applied loading, the number of cycles, dislocation density, and the residual stress gradient. The relaxation behavior difference under cyclic loading between ferrite and austenite is discussed.

Residual Stress Relaxation of Shot Peened Deformation Surface Layer on S30432 Austenite Steel under Applied Loading

The relaxation of residual stress in shot peened surface layer on S30432 austenite steel under static and cyclic loading was investigated. The results revealed that the compressive residual stresses were relaxed under applied tensile stress. The relaxation of residual stresses in longitudinal direction was more obvious than that in transverse direction. And when applied stress was beyond the yield strength of the materials, the relaxation of the compressive residual stress was drastic. Under cyclic loading, the results showed that the relaxation behavior was determined by the applied loading and the number of cycles. And the fast relaxation of the compressive residual stress took place in the first few cycles then became stable gradually. Finally, a model was used to quantitatively predict the compressive residual stress under cyclic loading with different applied tensile stresses. [doi:10.2320/matertrans.M2012111]

Mechanical and microstructural characteristics of the dissimilar materials butt joints by hybrid CO2 laser-gas metal arc welding

This paper intends to present the applicability of hybrid [CO2 laser+gas metal arc (GMA)] welding process to dissimilar materials AH32 and STS304L by clarifying the mechanical and microstructural characteristics of hybrid welded joints. In order to observe the mechanical phenomena on dissimilar material hybrid welded butt joints, two-dimensional thermal elastoplastic numerical analysis has been carried out. For this, the quasistate heat source model for simulation has been determined considering the hybrid welding characteristics. Based on the thermal history obtained by using this heat source model, the residual stress distribution in welded joints is predicted and found to be in reasonable agreement with the experimentally measured values. The result shows that maximum welding residual stress in longitudinal direction (σzz) in dissimilar material (AH32-STS304L) welded joints has occurred in the STS304L side by about 5% than in the AH32 side of welded joints. However, the equivalent stress of dissimilar material welded joints shows almost identical values as those of similar material (AH32 and STS304L) welded joints. The microstructures of weld metal exhibit well distributed platelike shaped ferrite in the matrix instead of dendritic structure. No weld defect has been detected and the second phase strong in brittleness is not observed on the interface between head affected zone (HAZ) and base metal as the scanning electron microscope-energy dispersive spectrometer (SEM-EDAX) analysis shows.