Surface hardening of high carbon content material - e.g. cast iron, by plasma surface remelting avoiding martensite prodn.

摘要

(A) In the prodn. of a hardened surface layer on workpieces of high carbon content materials by using an energy beam to produce a molten track while the workpiece and the plasma jet are moved independently of each other, the novelty is that the thermal energy introduced per unit vol. is controlled so that the temp. in the workpiece below the molten track is higher than the martensitic transformation temp. and ensures cooling in the workpiece below the solidified track outside the martensite region. (B) Appts. for carrying out the process is also claimed. USE/ADVANTAGE - The process is useful for hardening cast iron camshafts by plasma arc surface remelting. It produces a defined hardened depth, width and structure without the need for preheating to prevent martensitic transition zones which cause under-seam cracking.