Effect of Cooling Rate and Nb Composition on Non-Isothermal Austenite Grain Growth Kinetics in Nb-HSLA Steel during Hot Rolling

Abstract:

Abstract. The strength of a final product of steel is affected by its final austenite grain size.Almost applied models for grain growth based on Beck and Sellars equation , which has the isothermal condition assumption; whilst most of the materials processing take place under non-isothermal condition. The purpose of this research is to find the effect of Nb and cooling rate to the austenite grain growth model of HSLA-Nb steel to predict the Austenite grain size after hot rolling process in non-isothermal condition .The two composition of 0.019 and 0.056% Nb of HSLA-Nb was hot-rolled about 0.3-0.4 deformation at a temperature of 900-1100⁰ C, followed by cooling rate of 7-11 ⁰ C/s, in a time period of 25-40 second, and quenched by using water jetspray. Austenite final grain size was measured . The work shows that the higher Nb content of steel with higher cooling rate will reduce the final austenite grain size . It was also found that the new non-isothermal austenite grain growth after hot-rolled illustrated as a function of cooling rate,which obtained by modifying the previous established model by a cooling rate parameter 1/Cr^m, and it was more precision compared to previous grain growth equation.

• Periodical: Advanced Materials Research (Volumes 479-481)
• Pages: 414-420
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.479-481.414
• Online since: February 2012
• Authors: Myrna Ariati Mochtar, Azwar Manaf, Eddy S. Siradj
• Keywords: Austenite, Graingrowth, Hot Rolling, Kinetic, Nb-HSLA Steel

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