INDUCTION HEATING PROCESS FOR MELTING TITANIUM (COLD-WALL CRUCIBLES, SEGMENTED AND NON-SEGMENTED).

Studies were initiated to test the feasibility of cold-wall induction melting for reactive metals such as titanium. Equipment designed and used to carry out experimental melting tests consisted of a 630 KVA induction regulator, capacitor bank, 450 KW 60-cycle induction coil, and standard control panel with manual and automatic controls. The induction coil (17-in. I.D., 17 in. high) was exterior to the crucible and surrounded the crucible (14-in. I.D., 36 in. high) and its stainless steel water jacket. A machined section of an ingot was used to initiate melting. Vacuum was used for the closed system during melting tests. Three types of cold-wall crucibles were investigated. The first was a four-segment copper crucible, the second a non-segmented silicon bronze crucible, and the third a two-segment copper crucible coated with BeO. Attempts to melt titanium in an induction field in a cold-wall crucible were generally unsuccessful. Of the melting attempts made, the most encouraging results were obtained using a BeO-coated two-segment crucible. All indications point to the use of a non-segmented crucible of high resistivity for successful melting. (Author)