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The Brittle-Ductile Transition Temperature in the Solidification of Cast Fe-C-Mn-S Alloys

1992; Taylor & Francis; Volume: 5; Issue: 3 Linguagem: Inglês

10.1080/09534962.1992.11819108

0953-4962

A. Chojecki, I. Telejko,

Metallurgy and Material Forming

The influence of alloying elements on the hot-cracking of cast steel may be explained by their effect on the length of the liquid film separating the crystals in the solidification range. Below a certain length, the material becomes ductile, and crack formation is no longer possible. This length determines the brittle-ductile transition temperature. The influences of sulphur, carbon and manganese contents on the transition temperature have been studied using a simulation model for the growth of equiaxed grains. The range of brittleness, and hence hot-crack susceptibility is determined by the sulphur content. Carbon and manganese have little direct influence, but change the sulphur distribution between the solid and liquid phases, so influencing the length of liquid film at the grain boundaries.For the verification of computed results, mechanical properties of samples of different cast steels in the solidification range have been tested. Scanning electron microscope examination reveals that failure occurs along grain boundaries partly covered by a liquid phase rich in sulphur. Results of experimental studies have confirmed the theoretical predictions.