hascompletedfouryearsofitsplanned10-yearlife.ThoughCPM_VIMCRU®20TMhasshownahigher compressive yieldstrength than440Cmaterials, thematerial islimitedtonon-corrosive environments. Theadvantage ofPMmaterials isthattheymaybemanufactured withhigheralloycontents than conventional steels,sincecooling ratesfromthemolten stateareontheorderof104to108°C/second, compared to10-1°C/second, typicalforconventional ingotmetallurgy. Thisfastcooling rateallowsfora finegrainsize,ahighlyalloyed matrix,andtheformation offine(<5pm)homogeneously dispersed primary carbides. Essentially, thegasatomized powder particle maybeconsidered amicro-casting. Higherlevelsofcarbide formers maybeaddedtotheinitialmelt,producing agreater volume fraction of primary carbides. Aftermelting andatomization, thepowder metalisclassified byscreening (250pm maximum particle diameter istypical), blended tohomogenize theparticle sizedistribution, encapsulated inamildsteelmold,evacuated andhermetically sealed, andthenconsolidated tofulldensity viahot isostatic pressing (HIP).Fromthispoint,conventional steel-making processes maybeusedtoconvert the consolidated powder tobarform.PMmaterials typically exhibit improved hotworkability duetothe inherently finegrainsizeandlackofalloysegregation. Screening classifies thepowder suchthatthemaximum theoretical inclusion sizeislimitedtothesieve opening size,important forrollingcontact fatigueresistance. Insomecases,non-metallic inclusion levels arecapable ofmeeting specifications forvacuum induction melted plusvacuum arcremelted (VIM-VAR) qualitybearing steel[1].AgivenPMtoolsteelalloydisplays atoughness advantage overconventional toolsteel,duetotheabsence ofcarbide banding, coarse carbides, andcarbide angularity [4].Another advantage inherent withPMmaterials isinnon-destructive testing(NDT). Higherlevelsofresolution are possible inultrasonic inspection, whichdecreases thelikelihood ofalargeinclusion fromgetting into service. Asecondary benefit seeninPMtoolsteelsistheattainable surface finish,whichisconsiderably finer thanconventional toolsteelsduetothesmall,evenlydispersed carbides, whichhavelesseffectonthe surface roughness whenpullouts occur.Thishasbenefits inreducing noiseinoperation andinitialrun-in contamination. However, itmustbekeptinmindthattheimproved wearresistance makesitmoredifficult toachieve anearfinishdimension, sospecialized machining andgrinding equipment isoftenrequired. VIMCRU®60TMDevelopment Twochemistry modifications ofCPM®VIMCRU80TM,acommercially available corrosion resistant tool steel,weredeveloped. Byincreasing vanadium carbide contents ofthesesteels,metal-to-metal, abrasive andcorrosive wearresistance properties improve [5].Nominal compositions fortheCPM®VIMCRU80TM chemistry variations (CPM®VIMCRU®60TMand98VN084) andothercorrosion resistant bearing materials maybefoundinTable1. Table1.Corrosion Resistant Bearin¢ Material Com Material C CrMo-Ni V 440C 1.05 170.5.... 440N-DURTM[6] 0.65 14.5 ...... BG42_' 1.15 14.5 4--1.2 Cronidur30_[7] 0.33 15.5 1..... Pyrowear_675[8] 0.07 131.82.60.60 CPM_VIM CRU_80TM 2.35 14 1--- 9 CPM_VIM CRU_60TM 3.25 142.5--12 98VN084" 3.4 14 1--14.5 CPM_MPL-1 3.75 24 3-- 9 Compositions arereportedinwt.%. *Experimental Grade)ositions andHardnes,, Other Carbide Volume% -- -16 .1N <16 -- 16 .3N 4.5 5.4Co ? -- 23  28 --- 31.5 -- 46Levels Attainable Hardness I_+1,Rc)59 61 62.5 59 64(case) 62 64 63 64 Threepilot-size heatseachofCPM®VIMCRU®60TMand98VN084 weremeltedandatomized toyield enough powder toproduce alarge,commercial-size compact. Thecompacts wereHIP,GFMradial 140