Study of vacuum induction melting process of TiNi shape memory alloys

The effects of melting time, crucible diameter and ingot mass on chemical homogeneity and the content of carbon and oxygen impurity in TiNi alloy were studied by vacuum induction melting in graphite crucible. The results show that the impurity content is increased with an increase in melting time and A/V ratio, and the effect extent on carbon content is much greater than that on oxygen. The A/V ratio has a close relationship with the crucible diameter and ingot mass under the coordinative condition. The 10-20 kg ingot with few impurity and excellent homogeneity can be obtained by adopting 10 min+15 min melting time plus 160 mm diameter crucible.