Effect of Heat Index on Microstructure and Mechanical Behavior of Friction Stir Processed AZ31

Study of top sheet thinning during friction stir lap welding of AZ31 magnesium alloy

“…With the current welded material having an average grain size of ∼8·6 μm, the fracture strength of the current welds is expected to be in the range of 200–275 MPa, since these are the lower and upper bounds of tensile strength corresponding to the easy activation or full suppression of the basal slip. Specimens tested under AS loading also exhibit a linear relationship with the EST by comparing current data with those (similar hooking geometry) of Chen et al 27 However, the fracture strength based on the best linear fit is significantly smaller than what can be inferred from previous defect free specimen tensile testing 26. The stress concentration at the tip of the hooking feature is likely the reason for the lower computed fracture strength for AS loading.…”

“…The slope of the fitted line indicates the fracture strength of the material in the nugget region. Previous examinations of the tensile strength of friction stir processed AZ31-H24 magnesium alloys resulted in an ultimate tensile strength of ∼200 and 275 MPa along the welding direction and perpendicular to the welding direction respectively for a grain size range of about 3–10 μm 26. With the current welded material having an average grain size of ∼8·6 μm, the fracture strength of the current welds is expected to be in the range of 200–275 MPa, since these are the lower and upper bounds of tensile strength corresponding to the easy activation or full suppression of the basal slip.…”

“…Previous examinations of the tensile strength of friction stir processed AZ31-H24 magnesium alloys resulted in an ultimate tensile strength of ,200 and 275 MPa along the welding direction and perpendicular to the welding direction respectively for a grain size range of about 3-10 mm. 26 With the current welded material having an average grain size of ,8?6 mm, the fracture strength of the current welds is expected to be in the range of 200-275 MPa, since these are the lower and upper bounds of tensile strength corresponding to the easy activation or full suppression of the basal slip. Specimens tested under AS loading also exhibit a linear relationship with the EST by comparing current data with those (similar hooking geometry) of Chen et al 27 However, the fracture strength based on the best linear fit is significantly smaller than what can be inferred from previous defect free specimen tensile testing.…”

“…Specimens tested under AS loading also exhibit a linear relationship with the EST by comparing current data with those (similar hooking geometry) of Chen et al 27 However, the fracture strength based on the best linear fit is significantly smaller than what can be inferred from previous defect free specimen tensile testing. 26 The stress concentration at the tip of the hooking feature is likely the reason for the lower computed fracture strength for AS loading.…”