Abb. 3. REM-Aufmhme cines gcitzten AnschU ' von diffusionge-rchwei6tcn SSiC-BauteiIen. pII. 3. SEM of nu polished and etched seaion of a diffusion bonded SiSiC-pica (short aide of the picturc 25 pm).Ein wcitczer DiffusionsschweiSversuch wurde mit stranggc-preEtcm Refel-Material durchgefiihrt. Bei sonst gleichen Versuchsbedingungen bctrug die VerJchweiSzeit 6 h. Es wurdc cine Festigkeit von 269 f 61 Nlmm' emicht. Die Hafte der Probcn brad dabci nicht in der Verbindungsstelle sondern im Grundmaterial! Bei entsprechendcr Wahl der Venuchsparameter kann also mit dcm Diffusionsschwei6en'cine Festigkeit errcicht werdcn, die in H6hc dcr Grundfestigkeit liegt.Bei dicsen Vemchcn zcigte sich, eincrscits an den unterschicdlichen Rauhtiefewcrten gleich bcarbeiteter Probcn andererseits an dcr grokn Streubreite dcr Fcstigkcitswertc, daB gcMgfiigige GefiigeinhomogeniGten sich stark auf die Materialeigenschaften auswirkcn. Abb. 3 zeigt die rasterclektronenmikroskpischeAufnahme eincs geetztcn Schliffs einer Verbindungsstelle. Die Vcrbindung wird im wesentlichen durch cine porenfrcie Siliziumschicht cin Dickc von 0,3-0,4 pm gcbildet. Es gibt einige Stellen, an denen Sic-Kiirncr direkt verbunden N sein scheincn . Die dargcstellten Ergebnisse sind nicht ohne weiteres auf Material bczogen von verschiedcnen Herstellem Obertragbar, do& li& sich der proZC6 an die unterschicdlichen Gefiigebc-dingunBen anpassen wie inzwirchen weitere Versuche gezeigt habcn . Uteratur 1. 20 MW,-GasgcNhlter Sonnenturmkraftwerk GAST. -B m 5223 Gf7 burbcitct voa den F i n Interatom. MAN, MBB und Dornier System. 2. P. Wehmky, W. M e h e c k , oberblick Uber das 2 0 MW,-Gasgcm t e s So-ntunnkrrftmrk GA!ST. Stahubericht S o n n~~~rpie VDI (1W) 911. 3. G. W i h m n , Kcmiache Werkstoffe for den WIrmctaurchcr cines Sonncntunnkraftwcrks. Sprechsaal If3 (1980) 915.Heat E x c h q e r Gas Turbine Application. Roc. Brit. Cemm. Soc. (1978) 31. G. W i h m n , W. Heidw, Hentcllung vonKompoaentcn aus Siziumarbid fih das Sonncntwmkdnwrk GAST. Sprcchsaal, im z U r~V n r p l b d u n g~~~M~r # 1 -u n d dumbaMndlg.n S U h h Es wurdcn vier femrisch-austcnite Stahltypcn im Hinblick auf cine a-Phrrcn-Venpr6dung dwch Einwirken von Tcmpczaturcn im Bereich von 700 bis 900 'C untenucht. Die Ergebnisac h e n cine gcwisscc Empfindlichkeit solcher StPhk crkenocn. was bci der Werk-StOffRuZWshl berllcksichtigl werden mu& AuBerdem wurdc gucigl, did stcigender AustenitgcNt die Ausbildung von a-Phlcc f6rdcrt. Molybdin ah Legierunlpclcment beghstigt dic a-Phhucnbildung r h r vie1 stlrker ah Chrom, es erweitcrt den kritischcn Temperaturkmch Ndcm ktrlkhtlkh N h6hcren Temperaturen. Weiterhin wurdc ein ,,a-Aquivdent" enrbeitct. durch das fih vcrsehiedene StahIqualiUtcnbaaiercnd auf h e r Zusrmmcasctzunghalb-quantitative Verglcichc hinsichtlich der Gcfahr einer a-Pbascn-Vcmpr6dung angestcllt werden k6nncn. z. werk8tof€tccll. 22, m 2 3 4 (1981) 0 0 4 e 8 6 8 8 1 [ 1 m~s u 2 . m 229 0 Verlag Chemic GmbH, D m Wcinhcim, 1981
Thermal-fatigue properties have been investigated and compared in five standard hot-work tool-steel grades and one newly developed grade. The results demonstrate that heat-checking resistance, hot yield strength, and temper resistance can differ considerably between different martensitic hot-work grades of rather similar alloy type. The very best resistance against thermal fatigue is obtained with alloys having the highest hot yield strength and temper resistance. The new grade, which is based on a carefully balanced alloy composition, is found to offer superior properties in these respects. The findings stress further the importance of selecting a proper tool material when dealing with high-temperature hot-working applications in which the tool is subjected to large thermal fluctuations.MT/812Tools used for the hot working of metals and alloys are subjected to high temperatures, and usually also to severe thermal cycling. A main problem with tool materials for hot-working applications, and particularly for die casting, is therefore the occurrence of thermal fatigue or heat checking, which is the accepted technological term for thermalfatigue cracking. Thus, one of the most important technical properties of a hot-work tool steel is its resistance to thermal fatigue. This complex 'property' is influenced by several factors but, concerning hot-work tool steels, recent considerations L2 have shown clearly that basic material parameters, such as the thermal-expansion coefficient, hot yield strength, and temper resistance play decisive roles in thermal-fatigue behaviour. Accordingly, when developing or selecting hot-work tool steels for high-temperature applications, thermal-fatigue resistance should be considered carefully. Thermal-fatigue behaviour of a material, however, is difficult to investigate under laboratory conditions and, in contrast with most simple mechanical properties, there is no standardized test method in this case. In the last few years Uddeholm has developed a technological test method especially intended for the thermal-fatigue testing of hot-work tool steels. 1 Several hot-working grades have now been studied by this method. In the present paper the results from five commercially well established~artensitic grades and one newly developed grade of a si ilar type are presented and discussed with respect to hot yi ld strength and temper resistance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.