TWO-STAGE PROCESS OF SURFACE-HARDENING WORKPIECES OF HARDENABLE FERROUS ALLOYS

摘要

1347555 Induction and plasma arc heating BOHLER & ZO AG Gebr 15 Sept 1971 [21 Sept 1970] 43056/71 Heading H2H [Also in Division C7] In a self-quenching process the surface is scanned by a beam of cold plasma which supplies energy at a uniform rate to produce elemental areas of metastable austenite having constant cross-sectional shape and properties, the plasma being arranged to conductively close a circuit operated at constant high frequency, particularly 10 to 100 mc./sec. The plasma may be formed from argon. Suitable apparatus incorporates a frequency-stabilized generator 1 connected through matching unit 6 to torch 2, the input power and reflected power being measured by meters 7 and 8 respectively. The torch comprises an electrode 9 of thoriated tungsten mounted in a tube 11 into which gas is introduced through inlet 11, and which has an outlet nozzle 14 to shape the jet 16.