Hot ductility improvement of copper-arsenic steel by rare earth cerium

Abstract

The effect of Ce on hot ductility of Cu-As bearing steel in the temperature ranging from 700 to 1100 °C was investigated using Gleeble-3800 thermal-mechanical simulator. The hot ductility evaluation and fracture morphology observation showed that the hot ductility was obviously improved as Ce content increased from 0 to 0.0290 wt%. Detailed, the upper limit temperature of the ductility trough was decreased from 1057 to 765 °C, and the temperature corresponding to the minimum reduction of area was decreased from 850 to 750 °C. The fracture morphology was overall transformed from the dominantly intergraular brittle failure to the ductile failure characterized by the large and deep dimples. Analysis of metallographic, inclusions and grain boundary elements suggested that increasing Ce content inhibited the proeutectoid ferrite formation, which enhanced hot ductility of the steel bearing Cu and As. Moreover, the competitive grain boundary segregation of the solute Ce and As in steel with 0.0022 wt% Ce without arsenious rare earth inclusions decreased the quantity of As distributed at grain boundaries and thereby improved the hot ductility. When the Ce content reached 0.0290 wt%, a large number of arsenious rare earth inclusions were formed, and the grain boundary segregation of As was further decreased As, which was more beneficial to hot ductility than that with the lower Ce content in austenite single phase region.