Abstract：In order to analyze the tensile deformation behavior of silicon-nickel alloyed austenite base low density steel at medium temperature,instron electronic tensile testing machine was used to analyze the tensile deformation behavior of Fe-28.64Mn-8.99Al-1.68Si-1.39 Ni-1.0C(Mn29Al9Si2Ni). The mechanical behavior of the low-density steel was studied by temperature tensile tests at 23-300 ℃. The strengthening and toughening mechanism of the steel was studied by SEM,TEM and thermodynamic calculation. The results showed that with the increase of strain,the stress-strain curve of warm tension mainly included several processes,such as elastic deformation,uniform plastic deformation and fracture,and there was no obvious yield phenomenon. With the increase of temperature,the strength of the steel decreases gradually,and the plasticity(elongation to fracture)increases first and then decreases and then increases. At 200 ℃,the plastic trough appears. At this time, the stress-strain curve and the strain hardening rate curve of the steel have obvious sawtooth characteristics,and the strain hardening rate has little change with the increase of strain. However,the zigzag characteristics of stress-strain curve and strain hardening rate curve at other temperatures are not obvious,and the strain hardening rate decreases gently with the increase of strain. The main strengthening and toughening mechanisms of the steel at 23-300 ℃ are κ-carbide strengthening,strain strengthening, twin-induced plasticity and dynamic strain aging strengthening. Low temperature dislocation mobility is poor for the promotion of twinning induced effect,Ni elements and Si elements twin inhibition,temperature increase twin inhibitory effect and temperature variations and promoting or inhibitory effect on dynamic strain aging is the steel in 23,100 and 300 ℃ obvious twinning induced plasticity and obvious dynamic strain aging under 200 ℃. The main cause of reinforcement. Dynamic strain aging strengthening is the main reason for the plastic trough of the steel at 200 ℃.
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