The effect of b and microalloying elements (v, ti, nb) additions on the austenite grain growth of low alloy steel

摘要

The effect of B and microalloying additions of V, V+Ti, V+Nb on austenite grain growth f low alloy steel containing 0.3~*% C, 1% Cr and 0.2% Mo was investigated. As a measure of austenite grain size the mean chord length of austenite grains was assumed. The boron content in investigated steel was in the range of 0 to 0.008%. The investigations were carried out in austenitising temperature range of 850 to 1100°C. Using the thermodynamic model the contents of undissolved compounds of carbonitride V(C,N) and boron nitride BN were calculated and the effect of undissolved compounds content on austenite grain size was investigated. Obtained results showed, that vanadium content below 0.1% was ineffective as austenite grain growth inhibitor of boron containing steel and austenite grain size of steel was higher compare to non-alloyed steel. The most effective for decreasing of austenite grains size of boron containing steel was addition of 0.18% V + 0.03% Nb.