Microstructure evolution and hardness distribution of linear friction welded AA5052-H34 joint and AA5083-O joint

Abstract

The microstructure evolution of the AA5052-H34 joint and AA5083-O joint fabricated by linear friction welding (LFW) was evaluated in a wide range of interfacial temperatures, i.e., applied pressures. The grain refinement of Al alloys with high stacking fault energy was found to be mainly dominated by discontinuous dynamic recrystallization (DDRX) at low temperatures. While, it was clear that grain refinement at high temperatures was dominated by continuous dynamic recrystallization (CDRX). In the joint of work hardened AA5052-H34 fabricated at low applied pressure of 50 MPa (above the 0.5 Tm), the annealing effect was more significant than the grain-boundary strengthening effect at the WC, leading to the softening. However, the increased applied pressure to 100 MPa resulted in the flat hardness distribution due to the increased strengthening by grain refinement. On the other hand, in the joint of annealed AA5083-O, the flat hardness was obtained at the lower pressure of 50 MPa, because both the low angle grain boundary length per unit area and dislocation density at the WC was almost equivalent to that of base material.

Keywords

• Microstructure evolution
• Dynamic recrystallization (DRX)
• Linear friction welding (LFW)
• AA5052-H34
• AA5083-O
• Hardness