Cross Wedge Rolling Forming Mechanism And Numerical Simulation Of 23-8N Heat-resistant Steel

23-8N is an austenitic heat-resistant steel used in extreme harsh environments.Due to excellent performance and economy,it is widely used in large and medium-sized diesel engine valves.23-8N,excellent valve material,has a wide range of applications,but the forming process immature.Cross wedge rolling-die forging forming has high efficiency and benefit.Taking valve preforms as the research object,the forming process of cross wedge rolling is studied: 1)At 1000~1180? and 0.01~10s-1,the hot deformation behavior of 23-8N is studied by hot compression test,and the stress-strain curves are obtained.The straincompensated Arrhenius constitutive model is established,and its prediction accuracy reached 0.976.Processing maps are established and verified by microstructure.The optimal hot processing parameters are determined: temperature range of 1120~1160°C,the strain rate range of 0.03~0.1s-1.2)The DRX behavior and microstructure evolution law of 23-8N are studied by hot compression test.The DRX model and grain size model are established.23-8N thermo-mechanical-microstructure finite element model is established,by combined with constitutive model and DRX model.The test is simulated in DEFORM.The multi-field coupled finite element model is verified by EBSD and SEM at macro and micro angles.It is confirmed that the model can provide reference for hot deformation behavior.3)Based on DEFORM,simulation study of cross wedge rolling for 23-8N valve preform is carried out.The forming mechanism of 23-8N cross wedge rolling is revealed.The influence of process parameters on forming quality is analyzed.Multi-objective optimization of the process parameters of cross wedge rolling is carried out.The forming angle,stretching angle and section shrinkage are determined as design variables.The spiral mark depth and necking are regarded as evaluation indicators.17 test groups are designed by the BBD.Based on test data,the response surface models of evaluation indicators are established.Determining the interaction between process parameters.Determining the influence law on the forming quality.The feasibility of the response surface method to optimize the process of cross wedge rolling is verified.Figure 56;Table 19;Reference 81...