Development of High Speed and low Temperature Superplastic Forgeable New Cu-base Alloy with Shape Memory Ability

由于黄铜经常具有腐蚀性，因此以水龙头为代表的供水相关产品已被规定使用青铜。1991年，日本工业标准（JIS）进行了修订，制造商可以自由选择材料。在放宽管制后，我们一直在利用市售的高耐腐蚀黄铜棒促进锻造和高速加工技术的应用。但黄铜不能铸造成复杂形状，无法克服水流空洞的冲刷腐蚀和应力腐蚀开裂。通过自主开发材料和锻造工艺，提高技术水平，通过控制组织和添加Sn，开发出了以60 Cu-40 Zn为基础的新型工业合金。这种新型合金具有优良的热加工性能、耐蚀性和热处理形状记忆能力。在800 K以下实现了超塑性成形净成形，该合金可作为超塑性耐腐蚀形状记忆Cu-Zn-Sn合金。

Water supply related products, represented by faucets, had been regulated to use bronze as brass frequently becomes corrosive. In 1991, the Japan Industrial Standard (JIS) was amended, and manufacturers could have freedom in selecting the material for the faucets. Following this deregulation, we have been promoting the application of forging and high speed machining technology by utilizing marketed highly corrosive-resistant brass rods. But brass cannot be cast to form complex shapes and has no way to overcome erosion-corrosion by water flow cavity and stress corrosion cracking. We promoted technology by self developing both materials and forging technology.As the results, the new commercial alloys based on 60Cu-40Zn were developed by controlling the microstructures and adding Sn. The new alloys have excellent hot workability, corrosion resistance and also shape memory ability by heat treatment. The net shape forging by superplastic forming was realized below 800K and the alloys can be used as superplastic corrosion resistant shape memory Cu-Zn-Sn alloys.