No abstract

Cryogenic treatments have been employed over the past three decades for both tool and high-alloy steels to improve their wear resistance, mainly through the transformation of retained austenite and the precipitation of fine carbides. However, as the enhancement of one material property is often at the expense of another, it is interesting to evaluate the effect of this type of treatments on the fracture toughness. The objective of the present work was to determine the plane-strain fracture toughness of a cryogenically treated low-carbon AISI 420 martensitic stainless steel by means of standardized fracture tests, performed in accordance with the ASTM E399 and ASTM E1820 standards. In this study, it was experimentally demonstrated that cryogenically treated specimens showed a simultaneous increase in the KIC and hardness of 30 % and 5 %, respectively, compared to conventionally treated specimens. Keywords: cryogenic treatment, carbide refinement, plane-strain fracture toughness, low-carbon martensitic stainless steel Obdelava s podhlajevanjem v zadnjih treh desetletjih, tako za orodja kot za visokolegirana jekla, pomeni izbolj{anje njihove odpornosti proti obrabi, predvsem zaradi preoblikovanja zadr`anega avstenita in zgo{~evanja finih delcev. Kakorkoli`e, izbolj{anje enega materiala je pogosto, vendar na ra~un drugega, zato je zanimivo oceniti u~inek takega tipa obdelave na lomnò ilavost. Predmet pri~ujo~ega dela je bila dolo~itev lomne`ilavosti kriogensko obdelanega nizkoogljikovega martenzitnega nerjave~ega jekla AISI 420, s pomo~jo standardiziranih testov zlomov, izvedenih v skladu s standardoma ASTM E399 in ASTM E1820. V {tudiji je bilo s poizkusi dokazano, da so kriogensko obdelani vzorci pokazali hkratno pove~anje KCI in trdote za 30 % in 5 %, v primerjavi s konvencionalno obdelanimi vzorci. Klju~ne besede: obdelava s podhlajevanjem, pre~i{~enje delcev, lomna`ilavost, nizkoogljo~no martenzitno nerjave~e jeklo

No abstract