Effect of lead on the crack propagation and the mechanical properties of Brass processed by ECAP at different temperatures

The effect of equal channel angular pressing on the microstructure and the mechanical properties of a 60-40 brass alloy and a brass alloy containing 2.5 wt% Lead was investigated. The process was carried out at 300 degrees C and 400 degrees C through the route C up to two passes. The microstructure of the specimens was evaluated using optical microscopy and scanning electron microscopy. It was found out that, after the second pass, some cracks appeared in the specimens at both temperatures. The investigations confirmed the existence of the liquid lead flow in the phase boundaries and crack walls at 400 degrees C, leading to the deeper crack formation, as compared to the specimen at 300 degrees C. Mechanical properties were evaluated through micro-hardness and tensile tests at room temperature. The results showed that the highest hardness and tensile strength corresponded to the specimen processes at 300 degrees C after two passes. In order to ensure a deeper study of the mechanical behavior of the specimens, dislocation density was measured using X-ray diffraction pattern; a drop of dislocation density at 400 degrees C was revealed.