Effects Of Different Plastic Deformation On Microstructure And Properties Of Iron-based Alloys

The effects of different plastic deformation processes on the microstructure and properties of iron-based alloys were investigated by different passes warm rolling and annealing experiments on different initial microstructure carbon steel and industrial pure iron.In the process of warm rolling,dynamic recovery and recrystallization in ferrite occurred,and grain size decreased with passes rolling.After eight passes warm rolling,the average grain size of industrial pure iron is 5.11μm,and martensitic steel and pseudo-eutetoid steel reduced to 0.77μm and 0.52μm respectively.According to the tensile test results,after eight passes rolling,the strength and plastic of industrial pure iron are low.As for martensitic steel,although its yield strength is high,the elongation is low and the uniform deformation stage is not found.However,the comprehensive properties of pseudo-eutectoid steel is significantly improved,the yield strength and uniform elongation is 1167.0MPa and 6.2% respectively,so the uniform deformation capacity is comparatively excellent.The annealing for martensitic steel and pseudo-eutectoid steel was carried out at 600 ℃ after eight passes warm rolling.The reason for grain size growing extent low with the extension of annealing time is that martensitic steel has a strongly thermal stability.The grain size of ferrite is distributed as bimodal after the pseudo-eutetoid steel annealing.The tensile test was carried out for the rolling and subsequently annealed specimen,it shows that the strength of the test material decreases gradually with the extension of annealing time.Under the same annealing time,the yield strength of pseudo-eutectoid steel is closed to martensitic steel,however,the uniform elongation is obviously higher,which contributes to better strength,ductility and uniform deformation capacity.The experimental results show that,compared with other materials under the same process,the strength and ductility of pseudo-eutectoid steel are significantly improved after warm rolling and annealing.The mainly reason is that the microstructure of pseudo-eutectoid steel shows a multi-scale grain band distribution or grain size bimodal distribution,which can cause the effect of strain gradient in the process of deformation,and induce geometrically necessary dislocations,enhancing work hardening ability.Thus,comprehensive properties are improved.