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

以水龙头为代表的供水相关产品已被规定使用青铜，因为黄铜经常具有腐蚀性。1991年，日本工业标准（JIS）进行了修订，制造商可以自由选择水龙头的材料。在放松管制之后，我们一直在利用市场上销售的高耐腐蚀性黄铜棒，促进锻造和高速加工技术的应用。但黄铜不能铸造成复杂的形状，也无法克服水流空腔和应力腐蚀开裂的侵蚀腐蚀。我们通过自主研发材料和锻造技术来推广技术。通过对60Cu-40Zn合金组织的控制和Sn的添加，开发了新型60Cu-40Zn合金。经热处理，新合金具有优良的热加工性、耐腐蚀性和形状记忆能力。在800K以下实现了超塑性成形的净形锻造，该合金可作为超塑性耐腐蚀形状记忆铜锌锡合金。

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.