A New Alloy System Having Autogenous Grain Pinning at High Temperature

This contribution proposes a new alloy in which a small volume fraction of austenite particles is used to pin ferrite grain growth at high temperatures. During the reheating process, when the temperature is higher than 1200 ℃, the coarsening of austenite particles is driven by volume-diffusion-controlled behaviour and ferrite grain growth is dominated by the pinning effect of austenite particles. At low temperature (<1280 ℃), grain growth occurred at a rate which is proportional to the particle coarsening rate; while at high temperature (>1280 ℃), grain growth is much lower than that expected without pinning. During the solidification process, austenite particles nucleate along ferrite grain boundaries and retard grain growth. Grain growth can be completely arrested with more austenite particle precipitates. This new alloy can be applied to control grain coarsening in the thin slab casting direct rolling process, grain size control in the HAZ of welds and grain growth resistance at high temperature.