Brass Processing Performance under Press
Alpha single-phase brass (from H96 to H65) has good plasticity and can withstand hot and cold processing. However, α-phase single-phase brass is prone to moderate-temperature brittleness during hot working such as forging, and its specific temperature range varies with the amount of Zn, generally between 200 and 700 °C. Therefore, the temperature during hot working should be higher than 700 °C. The reason why the medium-temperature α-brass medium-temperature brittle zone is mainly caused by the presence of two ordered compounds of Cu3Zn and Cu9Zn in the α-phase region of the Cu-Zn alloy system, and an orderly transformation occurs during heating at medium and low temperatures to make the alloy brittle. In addition, trace amounts of lead and antimony impurities in the alloy and copper form a low-melting eutectic film distributed at the grain boundary to cause intergranular cracking during hot working. Practice has shown that the addition of trace amounts of strontium can effectively eliminate moderate temperature brittleness.
Two-phase brass (from H63 to H59), in addition to a well-plastic α phase in the alloy structure, a β-solid solution based on the electron compound CuZn has appeared. The β phase has a high plasticity at high temperatures, while the β' phase (ordered solid solution) at low temperatures is hard and brittle. Therefore, (α + β) brass should be forged in the hot state. The beta brass containing more than 46% to 50% of zinc has a hard and brittle performance and cannot be subjected to pressure processing.