Analyzing the Influence of Microstructure on the Mechanical Properties of TIG Welded Joints processed by Friction Stir considering the sampling Orientation

Abstract

The contribution of the microstructural arrangement to the mechanical properties of friction stir processed Tungsten Inert Gas (TIG) welded joints is reported in this work. The TIG-welded joints were subjected to a single pass of Friction Stir Processing (FSP). The friction stir processed joint was sampled transversally and longitudinally, and different tests were conducted and studied comparatively. The microstructural analysis showed refined grains with varying degrees. The mean grain size for the transversally sampled specimen was found to be 11.48 µm, while the longitudinally sampled specimen had varying mean grain size from 7.32 µm to 15.09 µm. The varying mean grain size of the longitudinally sampled specimen is caused by the staggered arrangement of the microstructure. The tensile properties and the microhardness of the transversally sampled specimen were lower than those of the longitudinally sampled specimen. The ultimate tensile strength of the transversally sampled specimen was found to be 87.88 MPa which is lower than that of the longitudinally sampled specimen (133.83 MPa). The microhardness of the longitudinally sampled specimen fluctuated between 30 HV and 80 HV while the transversally sampled specimen had a maximum microhardness of approximately 57 HV.

Effect on Fatigue Behavior of Connecting Rod in Gasoline Engine

“…In case of fracture, dimples appear on the 45-degree shear lip. The ductile fracture form, resulting from the shear behavior, is elongated or C-shaped, and this parabolic shape may be characteristic of shear failure [11,14]. Figure 7(c) depicts a surface layer examination of the same area.…”

“…As portrayed in Figure 10, the maximum hardness at the connecting rod surface is 324 HV. The hardness decreases along the radial direction (0.45 mm) until the minimum hardness at the center of the shaft is 261 HV [4,14].…”