Effect of Interdendritic Impurity Segregation on Hot Ductility Behavior of Low‐Carbon Steels

Abstract

Comparison of reheating tensile test (RHT) and re-melting tensile test (RMT) reveals the effect of interdendritic impurity segregation on hot ductility in lowcarbon steels. Two low-carbon steels with different amounts [wt%] of impurity elements (Steel A: P ¼ 0.005, S ¼ 0.001; Steel B: P ¼ 0.01, S ¼ 0.004) are tensiletested at temperatures 600-1000 C after reheating to 1350 C and re-melting at 1570 C. Steel A shows similar hot ductility behavior in the RHT and RMT, whereas the high-impurity steel shows a significant decrease in hot ductility at 900 C in the RMT compared with the RHT. Crack initiation at the interdendritic segregation region is suggested as an origin of the degradation of hot ductility in the high-impurity steel. The effect of interdendritic impurity segregation on the hot ductility behavior of continuously cast steel is further discussed.

Effect of heat treatment processes on the microstructure and mechanical properties of low alloy structural steels with different impurity tin contents

“…It is widely known that tin, antimony and phosphorus tend to segregate at grain boundaries during heat treatment process, which reduces the interface energy of grain boundaries, weakens the binding force between grains, and accelerates the nucleation and growth of grain boundary micropore. Therefore, the existence of residual elements will seriously deteriorate the steel properties, such as reducing their ductility [4] and toughness [5][6][7][8], worsening hot ductility [9][10][11][12][13][14][15], acting as the origin of temper embrittlement [16][17][18][19] and aggravating surface hot shortness [20].…”