Improvement of formability of leaded α brass during hot working

AbstractIsothermal hot compression tests with a strain rate of 0·1–0·4 s-1 were carried out at 973 K on an α brass alloy containing 0–1·5 wt-% lead. The fracture behaviour was strongly dependent on both lead content and grain size. In leaded α brass, fracture occurred easily when the grain size was larger than ∼100 μm. In non-leaded α brass, no fracture was observed at any grain size. In the leaded brass, fracture occurred only at the free surface and was attributed to grain boundary sliding. The poor formability of leaded α brass was markedly improved by changing the phase of the specimen surface from α to β brass. This result suggests that the surface β phase suppressed the grain boundary sliding of the α grains.