Sinterizazio-atmosferaren eragina M graduko (ASP 30 ... - Euskara

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TABLE V Chemical analysis of M 23 C 6 Steel Particle Mo V Cr Fe Co (atomic %) trial atmosphere . This seems to be due to the fact that in the industrial atmosphere rich in nitrogen the MC carbides are transformed to MX carbonitrides and the possible transformation on cooling of the liquid to MX and austenite, which happens when MC carbide is formed, disappears or is shifted to much higher temperatures . This type of MC eutectic carbide was neither observed in T1, due to low V content of the steel . The presence of M 6 C eutectic carbides both under vacuum and industrial atmosphere seems to define the limit of adecuated sintering . The addition of carbon or the introduction of nitrogen through the atmosphere does not affect strongly the temperature at which the first M 6 C appears in each steel . But because the addition of carbon - in all cases - and the introduction of nitrogen - in some cases - decrease the optimum sintering temperature, the increase of concentration of both elements in the steel enlarge the sintering "gate" . The composition and morphology of the needle type eutectic carbide found in the T15 and T42 after important oversinterings in vacuum, is similar (adding W + Mo) to that found for steel M2 [16,17] and M42 [18] and identified as M 2C. Several works [17, 19, 20] have shown that M 2 C carbides are unstable and decompose during the cooling to M 6C and MC . In this work the cooling rate was very high and that could explain why this decomposition did not take place . To confirm this hypothesis, a T15 + 0 .2%C sample was cooled slowly in the furnace (20 K h - ') after an oversintering of 25 K . For this oversintering needle shape eutectic carbides were observed after the normal cooling of 250 K min - ' . In the metallographic analysis of the specimen after the slow cooling, this kind of needle shape eutectic carbides could not be found, but the coprecipitation of M 6C and MC carbides, indicating the possible transformation on cooling of M 2 C to M 6 C and MC as indicated by Fredricksson et al . [17] . A similar situation has been recently observed by Urrutibeaskoa et al. [14] in a M2 high speed steel . This needle type eutectic carbide was not observed in samples oversintered even by 50 K in the industrial atmosphere. It seems that the presence of nitrogen in the specimens sintered under the industrial atmosphere avoids the formation of this eutectic carbide, as has been observed by Steven [19] that by increasing the nitrogen content in M7 and M2 steels the formation of M 2C carbides is difficult . W W + Mo Fe + Co T15 (this work) El 9 19 25 23 0 24 31 23 T15 + N (this work) El 7 8 25 47 1 12 19 48 T15 + N M 23 C 6 [21] 2 7 32 52 2 5 7 54 T15 + N C .G . [21] 2 11 27 55 0 5 7 55 T15 + N EI [21] 4 6 25 58 0 6 10 58 T42 (this work) El 18 13 24 34 3 9 27 37 T42 + N (this work) El 20 10 28 30 1 10 30 31 T42 M 23 C6 [22] 1 4 54 39 0 2 3 39 T42 C. cut [23] 14 8 18 49 5 6 20 54 The eutectic carbide called type I in the present work, found at the optimum sintering temperature and in some case 25 K below the optimum [18], has been also found by other authors in different high speed steels [15, 21, 22] . In Table V are compared the chemical composition of this type of eutectic carbide with other of the same kind found in the literature . This carbide type being rich in Cr and Fe could be of M 23C6 type . In Table V are also included the chemical analysis of some M 23C6 also reported in the literature, being the composition of this carbide similar to the type I found in the present work . 5 . Conclusions 1 . After cooling from the optimum sintering temperature in vacuum, primary carbides type M 6 C were present in all the steels analysed and MC, although present in T42 and T15, was not found in TI steel . 2 . After sintering in the industrial atmosphere the same M 6 C primary carbides are present, but the MC transform to a carbonitride MX of small size . 3 . In all steels analysed, after sintering at the optimum temperature, either in the atmosphere or in vacuum, small amounts of an eutectic rich in Cr and Fe has been found . 4 . Oversintering under vacuum at progressive higher temperatures produces eutectic carbides type : M 6 C, needle shape and MC. These last two carbides are not present when the sintering takes place in the industrial atmosphere . 5 . In all steels, sintered at the same medium, the chemical composition of the different type of carbides are the same if W + Mo and Fe + Co are added in atomic % . . References 1 . F . L . JAGGER and W . J . C . PRICE, (Suppl . 1) (1971) 407-28 . Powder Metall . 14 2 . A . S . WRONSKI, L . B . HUSSAIN AL-YASIRI and F . L . JAGGER, ibid . 22 (1979) 109-18 . 3 . C . S . WRIGHT and R . S 3389-98 . IRANI, J. Mater . Sci . 19 (1984) 4 . C . S . WRIGHT, A . S . WRONSKI and M . M . REBBECK, Met . Technol . 11 (1984) 181-8 . 5 . Internal report, University of Bradford, Engineering Materials Group (1987) . 6 . Unpublished work, University of Bradford, Engineering Materials Group (1987) . 2033
7. R . H . PALMA, V . MARTÍNEZ and J . J . URCOLA, Powder Metali . 32 (1989) 291-9 . 8 . C . S . WRIGHT . ibid . 32 (1989) 114-7. 9 . R . M . GERMAN, Int . J . Powder Metal!. 26 (1990) 23-34 . 10 . R . M . GERMAN, ibid. 26 (1990) 35-43 . 11 . P . MAULIK and - W . J . C . PRICE, ibid . 30 (1987) 240 . 12 . P . MAULIK, Scr. Metal!. 22 (1988) 441 . 13 . P . MAULIK, J . Mater. Sci . 24 (1989) 3463-68 . 14. I. URRUTIBEASKOA, R . PALMA, V . MARTÍNEZ and J . J . URCOLA, submitted for publication . 15 . S . KARAGOZ, I . LIEM, E . BISCHOFF and H . L . FISCHMEISTER, Metali . Trans. 20A (1989) 2695-700 . 16 . M . R . GHOMASHCHI and C . M . SELLARS, Metals Sc . 18 (1984) 44-8 . 17 . H. FREDRIKSSON, M . HILLERT and M . NICA, Scand. J . Metallurgy 8 (1979) 115-22 . 2034 18. R . PALMA, Ph.D . Thesis, E.S .I .I., San Sebastián (1990) . 19. G . STEVEN, J . J . HAUSER, T . A . NEUMEYER and J . M . CAPENOS, Trans . ASM 62 (1969) 180-94 . 20 . K . STILLER, L . E. SVENSSON, P . R. HOWELL, W . RONG, H-O . ANDREN and G . L . DUNLOP, Acta Metal!. 32 (1984) 1457-67 . 21 . C . DOMÍNGUEZ, Tesis Master en Metalurgia Mecánica y Física . ESII, San Sebastián (1988) . 22. C . S . WRIGHT and R . S . IRANI, J . Mater . Sci. 11 (1984) 3389-98 . 23 . C . KIM, V . BISS and W . F . HOSFORD, Metal! . Trans. 13A (1982) 185-91 . Received 3 July 1990 and accepted 31 January 1991
Page 1 and 2:
Jakintza-arloa: Ingeniaritza Sinter
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Eta hau izan da nire bizitza orain
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Javiri neuk baino ondiokan poza hau
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ESKERRAK Lan. hau burutua izan bald
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"SINTERIZAZIO-ATMOSFERAREN ERAGINA
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austenita kopurua % 5-ekoa bakarrik
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AURKIBIDEA 1 . Sarrera . 11 1 .1 Po
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Taulak . 58 Irudiak . 62 4.Emaitzak
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Irudiak . 173 6 . Ondorioak . 175 7
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1 . ATALA : SARRERA . CAPÍTULO 1 :
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1. INTRODUCCIÓN La vía de la pulv
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Es Europa quien lidera la investiga
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tabilidad química y resistencia a
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Las diferencias en el coste de sint
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de sus propiedades, se ha anticipad
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Por ello, y a fin de comprobar si e
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2 . ATALA : BILDUMA BIBLIOGRAFIKOA
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2 .1 Constituyentes 2 . RECOPILACI
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En los dos procesos los hornos se c
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Debido a la elevada velocidad de so
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La presencia del hidrógeno hace a
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asumirse que los aceros rápidos ob
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Los aceros rápidos de herramientas
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elementos de aleación para que se
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nización, para una temperatura det
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Se introdujeron los factores de int
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2 .4 .2 .2 Tenacidad en probetas ci
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plástica, condiciones de L.E .F.M
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La Fig . 2 .6 /62/ presenta esquem
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Mientras que Lc en condiciones de f
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Sin embargo, cuando la grieta encon
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agrietadas por fatiga, un valor de
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una LVDT para medir la deflexión e
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4 .5 GPa, en cambio, ésta disminuy
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tura corresponden a inclusiones o c
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en que C es la mitad del espaciado
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donde Ey corresponde a la deformaci
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IRUDIAK FIGURAS
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C) 925 900 875 850 825 800 775 Q IV
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as 11 ,IN h, hk I B ----~ a 2 .7 .
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3 .1 Hautsen karakterizazioa 3 . TE
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3 .4 Sinterizazioa Sinterizazioak 6
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lortutako txirbila xehekatu eta gar
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hartu ziren kontutan : Banadio-, Kr
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Aq, B q , Cq eta D q ondoko koefizi
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µ = kontutan hartutako fasearen zu
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Tratamendu Termikoak sinterizaziora
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neurtu zen, zein beti agertu zen ma
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Probeta bakoitzaren haustura-azal b
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A arrabolen arteko distantzia da, C
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Hortaz, haustura-erresistentzia, de
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TAULAK TABLAS
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Materiale Sinterizazio- Atmosfera P
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IRUDIAK FIGURAS
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0 w 0,050a W= Iamm 9 = i2rrrarr 3 .
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4 . ATALA : EMAITZAK . CAPÍTULO 4
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4 .1 Sinterización 4 .1 .1 Acero P
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Metalografía : Las muestras sinter
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en los MX, probablemente debido a q
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sinterizaciones de 30°C sin que va
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La temperatura de aparición de est
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El proceso de sinterización result
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con grafito respectivamente, se obs
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Los MX encontrados en el Px30 son m
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4 .2 Tratamientos Térmicos 4 .2 .1
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Se midió el tamaño de grano de la
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ción . Cada punto es la media arit
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Mientras que la dureza de temple de
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Durezas Se midió la dureza a todas
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4 .3 Ensayos Mecánicos 4 .3 .1 Ens
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A partir de dichas curvas se calcul
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ésta, hasta llegar al máximo de d
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y para más altos contenidos en aus
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Deflexioaren neurketa makinaren def
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En el caso del Px30 se estudió no
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Módulo de Young El módulo de Youn
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Para durezas altas, las probetas de
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Transformación de la austenita Par
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superficies de contacto entre part
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TAULAK TABLAS
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4.1V Taula : Px30 altzairuaren karb
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4.X Taula : Eutektikoen agerpen-ten
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4.XIV Taula : Barker saiakuntzen em
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IRUDIAK FIGURAS
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4 .2 . Ir. : STO- jn sinterizatutak
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E 70 60 50 40 30 20 10 0 1 0 o ' --
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8 .5 • O • •o .11 ¡ L] 0 0 E
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Co H H 70 60 50 40 30 20 10 1 o 1 1
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4 .14 . Ir . : Hutsean sinterizatut
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s. .r ~ U C6 • 20 • b 10 • N
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(o 1000 900 800 700 600 CD Tenplatu
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a 10 Nm 4 .21 . Ir . : Gasean sinte
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4 .23 . Ir . : Gasean sinterizatuta
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L7 A 900 850 800 650 600 550 ' -L 1
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1000 900 800 700 0 -? AXo}- APERTUR
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Barker zailtasun-saiakuntza . Ensay
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4 .37 . Ir . : Lau puntutako makurd
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N Q) 1 .6 1 .4 1 0 .6 0 - 911 -O ~O
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Lau puntutako makurdura-saiakuntza
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Lau puntutan makurdura-saiakuntza .
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Lau puntutako makurdura-saiakuntza
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5 . ATALA : EZTABAIDA . CAPÍTULO 5
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5 .1 Densificación 5 .1 .1 Tempera
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con el mismo o también con que al
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con lo cual se obtienen los valores
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donde fvj es la fracción volumétr
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sido también encontrado en otros a
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En la figura 5 .4 se han agrupado e
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mas de sinterizado de los mismos ac
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dustrial . En dicha tabla se compar
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Los carburos MC de los aceros estud
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5 .1 .6 Composición química de lo
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5 .2 Tratamientos Térmicos En la F
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También se ha comentado que en el
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cesos en carbono equivalente y este
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5 .3 Ensayos Mecánicos 5 .3 .1 Ten
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derando también los puntos de la b
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donde se puede estimar el valor de
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Estos contenidos se calcularon para
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-mediante la expresión (2 .31)- y
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do la misma dureza y cantidad de au
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En la figura 5 .13 se presentan est
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5 .1 Taula: Karburoetan sartzen den
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5.1V Taula : MC karburoen konposake
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5 .VIII Taula : Karbono baliokideak
Page 270 and 271: Material Sinterizazio- Atmosfera At
Page 272: IRUDIAK FIGURAS
Page 275 and 276: Frecuency (%) 100 90 80 70 60 50 40
Page 277 and 278: 100 80 ó ' 60 .J W H Z 40 w '< 20
Page 279 and 280: 1 .4 1 0 .8 0 .4 • 1 0 20 Hondar-
Page 282 and 283: 6 . ONDORIOAK 1 . % 90 N2-% 9 H2-%
Page 284: 7. ATALA: IRADOKIZUNAK . CAPÍTULO
Page 287 and 288: 7 . SUGERENCIAS 1 . Explorar hasta
Page 290 and 291: BIBLIOGRAFÍA (1) P. Payson ; "The
Page 292 and 293: (39) V .P. Martínez, R .H . Palma,
Page 294 and 295: (77) H . Takigawa, H . Manto, N. Ka
Page 296: ARGITARAPENAK . PUBLICACIONES .
Page 299: PUBLICACIONES . Publicaciones gener
Page 303 and 304: 306 Urr uibeaskoa et al . Metallogr
Page 305 and 306: 308 Urrutibeaskoa et al . Metallogr
Page 307 and 308: 310 Urrutibeaskoa et al . Metallogr
Page 309: 312 Urrutibeaskoa et al . Metallogr
Page 314 and 315: Figure 1 Microstructure of T42 + 0.
Page 316 and 317: Figure 3 Microstructure of T15 (1 .
Page 318 and 319: . . . 4 --s-- r a- 10 im Figure 5 M
Page 324 and 325: AVOIDING GRAIN GROWTH DURING THE SU
Page 326 and 327: 90 o GT42 80 o e GT42C VT42 * VT42C
Page 328 and 329: The presence of these MX carbonitri
Page 332 and 333: Publishing & Editorial The Institut
Page 334 and 335: INTRODUCTION Work carried out in th
Page 336 and 337: etter than 5 Pa during the sinterin
Page 338 and 339: gas atmosphere (see Table IV for qu
Page 340 and 341: - Needle type : observed only at hi
Page 342 and 343: -1o- (18) . These values would give
Page 344 and 345: Chemical composition of primary car
Page 346 and 347: CONCLUSIONS 1 . Addition of free ca
Page 348 and 349: Vasco, 1987, Bilbao, España . 13 .
Page 350 and 351: TABLE I Chemical analysis of as-rec
Page 352 and 353: TABLE IV Austenite grain size and p
Page 354 and 355: TABLE VII Chemical composition of C
Page 356 and 357: 8 .5 8 `/ U) 7 c o 6 .5 6 5 .5 1 1
Page 358 and 359: Fig . 3 : Microstructure at the opt
Page 360 and 361: L Ú y i3 70 60 30 - L 2 0 r- i Q L
Page 362 and 363: Frecuency (%) 100 90 - 80 70 - 60 -
Page 364 and 365: Frecuency (%) 100 90 - 80 - 70 - 60
Page 366 and 367: Fig. 8 a) Eutectic type carbides .
Page 369 and 370: March 10, 1992 Mr . J . J . Urcola
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INTRODUCTION Work carried out in th
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sintered is observed in Table II .
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DISCUSSION Densification Kinetics .
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particle size smaller than 1 µm, w
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primary carbides present in the mic
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REFERENCES : 1 . F .L. Jaegger and
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CONDICION I C N (%owt) (%wt) O (%wt
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CONDICION Temperatura de sintetizad
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1 a v~ 00 v~ N 0o N ( £ m3/2) kLIS
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u ( £ m0/ 2 ) xi ISNEIQ J 0 N M r-
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Fig . 5 . Microstructure of T15 spe
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N + D X O 0 0 0 0 0 0 0 I_ \o cn m
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O ó P .4 W ~ C7 3 ,a o z N ~ .~ á
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Q O x á á á 0 0 0 0 0 0 0 VI) L
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∎ ∎ o In o Ln o ~n tt M M N N (
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Ar, W X -r (3) a IU"EldWRI 0 M X A4
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Sinterizazio-atmosferaren eragina M graduko (ASP 30 ... - Euskara

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