油气田极端工况下等通道角挤压高锰钢微观结构与力学性能的温度效应OA

In response to extreme working conditions such as high temperatures and high pressures,low temperature gathering and transportation,and acid corrosion in oil and gas fields,traditional pipe materials(carbon steel,low-alloy steel)suffer from strength toughness imbalance and insufficient corrosion resistance,this study successfully prepared twinning induced plasticity(TWIP)steel with a chemical composition of Fe-25Mn-1.66Si-1.23Al,and subjected it to severe plastic deformation(SPD)through equal channel angular pressing(ECAP)at room temperature and 300℃.Different characterization methods were used to analyze its microstructure,and tensile tests were conducted before and after ECAP to test mechanical properties.The results show that after ECAP,the grains of TWIP steel are elongated,especially at room temperature,where the grain size decreases sharply.Transmission electronic microscopy(TEM)analysis confirmed the presence of twinning under all ECAP extrusion conditions.However,after multiple ECAP processes at room temperature and higher temperatures,it is more likely to induce complex secondary twinning morphology.One ECAP at room temperature will result in equal strain effects for two passes at 300℃.The strain hardening behavior is analyzed through the ln(dσ/dε)-lnσ plot,and the results show that annealed samples have relatively high strain hardening ability,while the strain hardening performance of ECAP treated samples gradually decrease with the increase of the total strain applied by ECAP.