Characterisation of Residual Stress and Plastic Strain in AISI304L Stainless Steel/Titanium Friction Welds(Mechanics, Strength & Structural Design)
Search this Article
In order to elucidate the characteristics of residual stress and plastic strain produced by AISI304L stainless steel to titanium friction welding operation, detailed FEM modelling was carried out. Heat transfer into a narrow zone, z=±20mm on either side of the bondline promotes residual stress and plastic strain formation. The peak temperature occurs in the AISI304L substrate. Adjacent to the bondline, σ_r (radial component of residual stress) and σ_θ (circumferential component) are tensile in the higher thermal expansion substrate (AISI304L) and are compressive in the substrate with the lowest thermal expansion (titanium). The σ_z (axial component) which markedly affects joint strength properties is tensile near the center of the component (where the stiffness is large) and is compressive at the periphery of the component, in material far from the bondline, σ_z is compressive near the center of the component and is tensile at the joint periphery. In particular, σ_z is tensile in the titanium substrate, except in regions extremely close to the bondline at the periphery of the component. Plastic strain components, εP_r (radial component) and εP_z (axial component) are large. However, εP_z is not the result of the severity of mechanical deformation applied during friction welding, it exists to satisfy the constant volume requirement. εP_θ (circumferential component) is small. Mechanical deformation of the titanium substrate is more sever than in the AISI304L stainless steel. The plastic strain distribution in the axial direction corresponds well with hardness distribution in finished joints.
- Transactions of JWRI
Transactions of JWRI 24(1), 121-125, 1995-07