_STP_408-1967.pdf

EROSION BY CAVITATIONOR IMPINGEMENTA symposiumpresented at theSixty-ninth Annual MeetingAMERICAN SOCIETY FORTESTING AND MATERIALSAtlantic City,N.J.,June 26-July 1,1966ASTM SPECIAL TECHNICAL PUBLICATION NO.408List price$20.00;30 per cent discount to memberspublished by theAMERICAN SOCIETY FOR TESTING AND MATERIALS1916 Race Street,Philadelphia,Pa.19103 BY AMERICAN SOCIETY FOR TESTING AND MATERIALS 1967Library of Congress Catalog Card Number:67-12411NOTEThe Society is not responsible,as a body,for the statements and opinionsadvanced in this publication.Printed in Baltimore,Md.March,1967 ForewordThe papers in the Symposium on Erosion by Cavitation or Impringe-ment were presented at the Sixty-ninth Annual Meeting of ASTM held atAtlantic City,N.J.,June 26-July 1,1966.The symposium consists of ten papers and eight discussions,andfocuses mainly on the damage mechanism and the material response toit.The symposium was sponsored by Committee G-2 on Erosion byCavitation or Impingement under the chairmanship of F.J.Heymann,Westinghouse Electric Corp.RelatedASTM PublicationsErosion and Captation,STP 307(1961),$4.00 ContentsIntroduction 1A Test Rig for Studying Impingement and Cavitation DamageJ.F.RIPKEN 3Discussion 18The Concept of Erosion StrengthA.THIRUVENGADAM 22Discussion 36Material Destruction Due to Liquid ImpactG.HOFF,G.LANGBEIN,AND H.RIEGER 42On the Time Dependence of the Rate of Erosion Due to Impingementor CavitationF.j.HEYMANN 70Discussion 100Water Jet Impact Damage in a Cobalt-Chromium-Tungsten AlloyD.J.BECKWITH AND J.B.MARRIOTT IllErosion of Steam Turbine Blade Shield MaterialsALLEN SMITH,R.P.KENT,AND R.L.ARMSTRONG 125Discussion 152Experience With a 20-kc Cavitation Erosion Testj.M.HOBBS 159Discussion 180Accelerated Cavitation Damage of Steels and Superalloys in Sodiumand Mercurys.G.YOUNG AND j.R.JOHNSTON 186Discussion 213Scale-Effect Investigation of Cavitation Erosion Using the EnergyParameterK.K.SHALNEV,j.j.VARGA,AND G.SEBESTYENDiscussion 236Correlation of Cavitation Damage with Other Material and FluidPropertiesR.GARCIA,F.G.HAMMITH,AND R.E.NYSTROM 239Discussion 280220 This page intentionally left blank EROSION BY CAVITATION OR IMPINGEMENT(With special emphasis on the interrelationships betweenmaterial properties and erosion damage)IntroductionFive years ago,during the 1961 Annual Meeting,ASTM held itsfirst Symposium on Erosion and Cavitation,the proceedings of whichwere published as STP 307.As a direct result of the interest stimulatedby that Symposium,Technical Committee G-2 was established,and the1966 Symposium was the first to be held under its sponsorship.In 1961six papers were presented;the 1966 Symposium heard eighteen presen-tations,including six from abroad.Of these ten are contained in thisvolume;some of the others will eventually appear in other ASTM pub-lications.There have been many symposia dealing with cavitation as a fluidflow phenomenon as well as a damage-producing phenomenon.Curi-ously though,there had been a notable lack of communication in thiscountry(though not in Europe)between those concerned with cavita-tion damage and those concerned with liquid impingement damage.The two ASTM Symposia are,to the best of my knowledge,the first inthis country to focus on the damage mechanism and the material responseto it,and thus on the common aspect of cavitation and impingementattackfor it is now widely(though not universally)accepted that theprincipal direct cause of damage in both instances is the mechanicalstressing due to the high-speed impact of a liquid surface upon a solidsurface,though corrosion can,certainly,enter the picture under ap-propriate conditions and mechanical and chemical effects can reinforceeach other.The mechanical stress theory was proposed by Cook in 1928,but over the years there have been many who doubted the possibility ofsufficiently high mechanical stresses and postulated principally chemicalmechanisms or a variety of other more fanciful mechanisms.I believethat the days of wild conjecture are over and that investigators todayat least talk the same language and agree on the kind of quesions to ask.This is not to say that all stimulating disputes have vanished:such stillexist,as for instance concerning the exact nature of the interaction be-tween mechanical and corrosive effects,and the exact meaning of thevarious phases observed in erosion rate-time histories.i 2 EROSION BY CAVITATION OR IMPINGEMENTASTM is interested in the properties of materials and the ways ofdefining,testing,prescribing,and controlling these properties.Thus,naturally,we are interested not only in the mechanism of erosion,butin how the resistance of materials to erosion can be objectively defined,how it can best be tested,and how test results should be interpreted,andwhether this property can be correlated with other known material prop-erties.Also of interest is the influence of the physical as well as chemicalproperties of the impinging liquid.All of these points are still in need offurther en