The evolution of the microstructures and hardness of a bainitic plate steelduring tempering at 650 deg C has been investigated. The steel was manufactured by RFC(relaxation-precipitation controlling phase transformati...The evolution of the microstructures and hardness of a bainitic plate steelduring tempering at 650 deg C has been investigated. The steel was manufactured by RFC(relaxation-precipitation controlling phase transformation) technique. A part of the plate wasreheated to 930 deg C and held for 1 h before quenched into water (RQ). No obvious change wasdetected by means of optical microscopy in the RFC steel tempering for 0.5 h, while dislocationcells were formed inside the bainite laths, accompanied by an obvious drop of hardness. The bainitelaths started to coalesce in some regions, but the sample hardness kept nearly constant duringtempering from 1 to 7 h. With further tempering, polygonal ferrite was formed in local regions whilethe hardness decreased dramatically. The RQ samples softened faster during tempering and finallytransformed into the polygonal ferrite completely. These results indicate that the thermo-stabilityof fine non-equilibrium microstructures is tightly related to their history.展开更多
基金The work was financially supported by the National Key Basic Research and Development Program of China (No.G1998061507) and CITIC-CBMM (No.2002RMJS-KY002)
文摘The evolution of the microstructures and hardness of a bainitic plate steelduring tempering at 650 deg C has been investigated. The steel was manufactured by RFC(relaxation-precipitation controlling phase transformation) technique. A part of the plate wasreheated to 930 deg C and held for 1 h before quenched into water (RQ). No obvious change wasdetected by means of optical microscopy in the RFC steel tempering for 0.5 h, while dislocationcells were formed inside the bainite laths, accompanied by an obvious drop of hardness. The bainitelaths started to coalesce in some regions, but the sample hardness kept nearly constant duringtempering from 1 to 7 h. With further tempering, polygonal ferrite was formed in local regions whilethe hardness decreased dramatically. The RQ samples softened faster during tempering and finallytransformed into the polygonal ferrite completely. These results indicate that the thermo-stabilityof fine non-equilibrium microstructures is tightly related to their history.
