Characterization of deformation induced surface hardening during cryogenic turning of AISI 347

The use of cryogenic cooling in material removal processes has been reported by several researchers. The objectives were enhanced tool life and an expanded range of machinable materials. In this paper, a novel application of cryogenic cooling is presented: its use achieve direct surface hardening of metastable austenitic steels during cutting. Metastable austenite can transform into martensite due to plastic deformation if a sufficiently low temperature is maintained. In order to use this effect during cutting, cryogenic conditions must be maintained at all times. With this approach, cutting and hardening can be combined in one process.