Investigation of the effects of holding times at cryogenic temperatures on residual stress distribution of aisi d2 tool steel

AISI D2 is cold tool work steel and is used widely due to the advantages such as its wear resistance, compressive strength and toughness. When the literature is reviewed, it is observed that researches associated with the effect of cryogenic treatment on residual stress are rather poor. Residual stress is very important since this affects some properties such as fatique life, wear resistance, crack propagation and stress corrosion which determine the service life of materials. In this study, effect of the holding time at cryogenic temperatures on residual stress of AISI D2 cold work tool steel is investigated. Results shows that tensile residual stress on surface of AISI D2 steel decreases with cryogenic treatment and subsequently turns into compressive residual stress on subsurface. While residual stress value on surface of the specimen for holding time (t_CT) of 24 h is 242,3 MPa in axial direction and 172.5 MPa in tangential direction, and in specimen conventionally treated is 321,5 MPa in axial direction and 316,8 MPa in tangential direction. There is no significant difference between hardness values, but carbide precipitation increases in specimen cryotreated for t_CT=24 h. Apart from this, surface roughness improves for cryogenic treatment. In comparison to conventional heat treatment and cryogenic treatment at various holding times, t_CT=24 h has better results regarding residual stress, carbide precipitation, and surface roughness.