Mold Copper Alloy Heat Treatment Process

Multi-aluminum bronze has been widly applied in some area such as machine industry, automobile and plane manufacture, shipbuilding industry and ocean industry because it possesses some super properties, for example mechanical properties wear-resistant, corrosive resistance, oxidation resistance. With the rapid development of modern industry, traditional trademark's aluminum bronze don't accord with usefulness request in the certain situation. So, many people who research science are exploiting a new- aluminum bronze and our team are researching a new- aluminum bronze that possesses high strength, high hardness and is made with die. In this paper the effect of as-cast microstructure on mechanical properties of multi-aluminum bronze, the transformation of microstructure of multi-aluminum bronze with homogenizing annealing were studied and optimizing technics of heat treatment. The results shows as following:1.The as-cast microstructure of multi-aluminum bronze are a phase,B ' phase, Y 2 phase and K phase. There are imbalance phases and supersaturational insoluable element and dendrite segregation in the as-cast microstructure, besides those, there are also insoluable element, intermetallic composite, impurities phase, nonmetallic lard on grain boundary. The as-cast of multi-aluminum bronze possesses high strength, high hardness but low toughness. Grain size, content of a phase, distributing of r2 phase ,shape of K phase impact on mechanical properties of as-cast multi-aluminum bronze. Grain size of as-cast multi-aluminum bronze is 0.000475cm, and it make the plasticity and toughness decrease; lack of a phase and coarse Y 2 phase distributing along grain boundary cause the brittleness of alloy. The main function of the K phase is dispersion-strengthening and the coarse flowery K phase deteriorate the mechanical properties of alloy to a certain extent.2.In low temperature homogeneous annealing, microstructure of multi-aluminum bronze are same to it's as-cast, and the alloy still possesses high strength, high hardness, but toughness has evidently declined trend.3.In a set of experiment that didn't vary time but temperature , the microstructure transformed most complete than others processes at 980 C homogeneous annealing, but at 950C homogeneous annealing hardness is highest than others.4.In a set of experiment that didn't vary temperature but time, we found the K phase were easily affected by the heat holding-time. At heating temperature 950 C,holding time 20h, the k phases have completed the homogeneous process from precipitating, growing to splitting, re-assembling,; At heating temperature 950C,holding time 2h, the ( a + Y 2) phase , a phase, y 2 phase have completed the homogeneous process. With increasing holding time, the Y 2 phase become coarse. According data of hardness, at heating temperature 950C .holding time 2h, the hardness arrive at the top.5.The Multi-aluminum bronze which had been oil quenched after holding 950 for 2h then tempered 500 for 5h had the best tensile strength 625MPa, hardness 41.17HRC,toughness 0.713kg f. m. The Multi-aluminum bronze which had been oilquenched after holding 950 for 2h then tempered 460 for Ih had the best toughness 0. 723 kg f. m, which had been oil quenched after holding 950 for 2h then tempered 580 for 5h had the best hardness 45.84HRC.