Converter & RH Vacuum Degasser

Selection criteria

Vacuum level, degassing time, alloy-addition accuracy.

Supply chain

Steelmaking and vacuum-degassing plants are built by a few global metallurgical engineering groups (SMS group, Primetals, Danieli) and Chinese state-owned design institutes such as CISDI. Motor makers do not buy this equipment, but it explains why electrical-steel quality differs by mill: impurity control here sets the loss of the final grade.

Buyer FAQ

Why does steelmaking matter if I only buy laminations?

Residual carbon, sulphur, nitrogen and oxide inclusions pin grain growth and domain-wall motion, raising core loss in non-oriented electrical steel. Mills that RH-degas every heat can hold C, S and N each in the tens of ppm (for example C ≤ 30 ppm). This is a large part of why the same nominal grade performs differently from different mills.

What should I ask a steel mill about its refining route?

Ask whether every heat of your grade goes through vacuum degassing, the aim and range for C, S, N, Si and Al, and how inclusions are controlled. Request heat chemistry and per-coil magnetic data, measured by Epstein frame (IEC 60404-2) or single-sheet tester (IEC 60404-3), and check that data from several coils are consistent.

What is magnetic ageing and how is it tested?

Residual carbon and nitrogen can precipitate as fine carbides and nitrides when a motor runs hot for long periods, increasing core loss over its life. A common test ages samples at 225 °C for 24 h and compares core loss before and after. For high-efficiency or high-temperature motors, specify a maximum loss increase after ageing in the purchase specification.

Where it is used