The use of Weibull Statistics to Quantify Property Variability in Fe-3Mn-0.8C Sinter-Hardened Structurally Inhomogeneous Steels

Abstract

Low carbon ferro-manganese and graphite powders were admixed to Höganäs sponge, NC100.24, and water atomised, ABC 100.30 and ASC 100.29, iron powders -to produce three variants of sintered Fe-3Mn-0.8C steel. These were pressed into tensile and bend specimens at 660 MPa, sintered in semi-closed containers for 1 hour in dry nitrogen or hydrogen at 1120 or 1250• C and cooled at 64• C/min. Both tensile strength and transverse rupture strength were examined using Weibull statistics. This paper presents the results of a study to develop and evaluate goodness of fit tests for the two-and three-parameter Weibull distributions. The study was initiated because of discrepancies in published critical values for two-parameter Weibull distribution goodness of fit tests and the lack of general three-parameter Weibull distribution goodness of fit tests for properties of PM steels.Keywords: strength of sintered steels, Weibull statistics, goodness of fit tests Aby uzyskać trzy warianty spiekanej stali Fe-3Mn-0.8C wytworzono mieszanki proszków: niskowęglowego żelazoman-ganu, grafitu oraz proszków żelaza firmy Höganäs: gąbczastego -NC100.24 i rozpylanych -ABC 100.30 oraz ASC 100.29. Z proszków tych zostały sprasowane, przy ciśnieniu 660MPa, kształtki próbek wytrzymałościowych przeznaczonych do wykonania prób rozciągania i zginania, spieczone następnie w półhermetycznych pojemnikach, w czasie 1 godziny, w suchym azocie lub wodorze, w temperaturze 1120 lub 1250• C, po czym chłodzone z szybkością 64• C/min. Zbadano wytrzymałość na rozciąganie i zginanie otrzymanych próbek przy zastosowaniu statystyki Weibulla. W artykule zaprezentowano wyniki badań mających na celu wykorzystanie i ocenę testów zgodności dla dwu-i trzyparametrowych rozkładów Weibulla. Badania podjęto z powodu rozbieżności publikowanych krytycznych wartości testów zgodności dla dwuparametrowego rozkładu Weibulla oraz ogólnego braku testów zgodności dla trzyparametrowego rozkładu Weibulla, w odniesieniu do własności stali wytworzonych techniką metalurgii proszków.

The Structure and Mechanical Properties of Ni-Mo PM Steels with Addition of Mn And Cu

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Microatmosphere Sintering of Cr–Mn Steel In Furnace Atmospheres of Flowing Hydrogen and Technical Nitrogen

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Nickel and Copper-Free Sintered Structural Steels Containing Mn, Cr, Si, and Mo Developed for High Performance Applications

“…Property variability in Fe-3Mn-0.8C sinterhardened structurally inhomogeneous steel was quantified using Weibull statistics [12]. Sintering in the alpha phase was minimised and, to avoid/minimise formation of oxide veins, was in a dry hydrogen-rich atmosphere.…”