高碳钢中珠光体在温楔横轧过程中的组织演变

Evolution of pearlite microstructure during warm cross wedge rolling

采用温楔横轧方法制备出表层具有超微细复相组织的高碳珠光体钢棒件,研究了珠光体组织在温变形过程中的演变．结果表明,珠光体组织中的渗碳体片层主要以弯曲扭折的形式协调塑性变形,表现出较强的塑性变形能力;剧烈塑性变形促进了渗碳体片层的球化,表层球化完全的渗碳体颗粒粒径均小于0．2μm;温楔横轧后铁索体基体发生丁动态连续再结晶,等轴铁索体平均晶粒尺寸为0．3～0．4μm,0．5R处和心部的渗碳体球化不完全,铁素体再结晶也不完全;铁索体晶粒的超细化和渗碳体片层的球化明显改善高碳珠光体钢棒件的塑性,温变形过程中应变、应变速率及温度分布的不均匀是引起组织性能差异的根本原因．

An ultrafine （ferrite＋cementite） structure has been produced through warm cross-wedge rolling （WCWR） at the outer layer of high carbon steel rod. Microstructure evolution of pearlite steel during warm deformation was investigated. The results show that the cementite lamella has better plastic deformation capacity, and the severe deformation accelerates the spheroidization of the cementite. The size of full spheroidized cementite particles is under 0.2 μm at the outer layer of high carbon steel rod, and the dynamic continuous recrystallization takes place in the ferrite matrix. The average size of equiaxial ferrite grains is about 0.3-0.4μm. However, the cementite is partly spheroidized, and the ferrite is also partly recrystallized at the 0.5 R and the center. Ultra-fined ferrite grains and cementite spheriodization improve plastic properties obviously. The asymmetry distributions of strain, strain rate and temperature are the mainl cause of the difference of the microstructures and the mechanical properties during warm deformation procession.