Wear Behavior of Cryogenically Treated AISI 420 Martensitic Stainless Steel

G. PRIETO; W. R. TUCKART

Cartagena,

Congreso; Ibertrib 2015. VIII Iberian Conference on Tribology; 2015

Cryogenic treatments havebeen employed over the last three decades in both tool and high-alloy steels toimprove wear resistance, mainly through the transformation of retained austeniteand the precipitation of fine carbides [1]. In this work the wear behavior ofcryogenically treated, low-carbon AISI 420 martensitic stainless steelspecimens has been studied with respect to that of conventionally heat treatedones.The tribological propertiesof the materials were assessed by means of ball-on-disk tests, under a range ofapplied normal loads, under a paraffinic aditive-free vaseline bath. The diskswere made of AISI 420 stainless steel subjected to two different heattreatments, namely, quenchedand annealed (CHT), and quenched, soaked in liquid nitrogen for 2 h andannealed (DCT). A 5 mm carbide tungsten ball was used as the counterbody. Wearbehavior has been characterized by wear volume, friction coefficientmeasurements and analyses of worn surfaces, wear debris and subsurfaces. It wasfound that the wear resistance of cryogenically treated specimens showedincreases ranging from 35% to 39% in comparison to the conventionally treatedones. The cryogenic treatment of AISI 420 stainless steeldecreases the average carbide size and produces a more homogeneous spatialdistribution of them [2]. These smaller carbides are related to a lower stressconcentration effect, therefore to a reduced amount of strain accumulation andconsequently, less sub-superficial cracking and delamination