Vacuum furnace is suitable for the high quality, high purity, refractory metal melting and heating, such as tungsten, molybdenum, tantalum, niobium, titanium, heat resistant alloy steel smelting and magnetic materials, high strength steel, stainless steel, tool steel, electrical material, heat treatment of die steel etc. Vacuum furnaces appeared around the 1930s. 1927 vacuum annealing furnace gt;