ISSUE 3/2012

/// 03
Tuttle, R.
Effect of titanium on the grain size of stainless steels

A series of stainless steel plate casting experiments were conducted to determine the role of titanium additions on the mechanical properties and grain size. The castings were produced using typical foundry practices and then sectioned into tensile bars and metallurgical samples. Tensile testing found no significant strength increase; however, the percent elongation of the high titanium samples was significantly lower than the baseline steel. Microscopy investigation of the samples found titanium carbo-nitrides present and the grain size decreased in the titanium containing heats. A Scheil solidification calculation predicted the titanium carbo-nitrides formed at the end of solidification, which meant they could not act as heterogeneous nuclei. The most probable explanation for the observed grain size decrease was that the titanium carbo-nitrides reduced grain growth as the castings cooled. It was also postulated that the decrease in grain size was not large enough to cause an observable increase in strength. 

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