Effect of Equal Channel Angular Pressing Pass on Microstructure and Mechanical Properties of Pure Tin

The forged pure tin plate with purity of 99.99% was treated by equal channel angular pressing (ECAP) for different passes (0-20 passes) at room temperature. The effect of ECAP pass on the microstructure and mechanical properties of the pure tin was studied. The results show that under the severe shear of ECAP, twinning and twin-induced recrystallization occurred in pure tin grains, and the grains were significantly refined. After ECAP for more than 12 passes, the grain refinement effect was weakened. With increasing ECAP pass, the texture strength and maximum orientation density of the pure tin decreased, while the hardness, strength and percentage elongation after fracture increased. Compared with those of the forged pure tin, the hardness, yield strength, tensile strength and percentage elongation after fracture after 20 passes of ECAP increased by 9.09%, 5.14%, 32.08% and 144.19%, respectively. The main strengthening mechanism of the pure tin was work hardening with ECAP pass of less than 8, and was fine grain strengthening with ECAP pass of more than 8.