Simulated effects of martensite start temperature, thermal conductivity and pore content on end quench cooling rate

ISSN： 1743-2901

Source： Powder Metallurgy, Vol.52, Iss.4, 2009-12, pp. : 282-290

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Abstract

Process modelling, based on finite difference methods, is used to show that the thermal conductivity increases, which typically attend the martensite transformation in steel, affect the cooling rate in the Jominy end quench test. A one-dimensional model, which includes the effects of material property variations, is presented that predicts slightly increased cooling rates with increases in the M_s temperature for fully dense steels and significantly increased rates for powder metallurgy (PM) steels. The model is based on earlier studies of the end quench test that initially showed increased cooling rates in PM steels versus fully dense ones and then went on to show water penetration of the pores as a causative mechanism. In the present study, it is shown that by combining a simple theory of this mechanism with the aforementioned M_s effects, it is possible to obtain cooling curves that display a marked resemblance to the experimentally observed ones of these earlier studies.