Research On Low-temperature Thermal Deformation Behavior For The EH36Steel And Prediction Of Straightening Force On Plate Heat Straightening

The demand for ship is rising with the rapid development and growth of world economy and trade. EH36steel, using in hull structure, is one of the high technical and value-added products. Straightening is indispensable in plate rolling, and the straightening model is affect the property, energy consumption and cost, etc. Hot deformation behavior is very important for straightening force. Due to the straightening temperature is usually in low temperature, and the flow stress is different between high temperature and low temperature, but the low temperature flow stress model is still inadequate. Therefore, the study on low temperature hot deformation behavior and straightening model for EH36steel has great significance.In this paper, single pass low temperature compression tests for EH36steel were conducted on Gleeble-1500thermal-simulation machine. The low temperature flow stress and straightening model is established. Based on the model contrast and the analysis of the measured data, the model is modified and verified. The result shows that the predicted value of straightening force is coincide well with the measured values. The main research content in this paper is as follows:(1) Consulted literature about ship and the straightening process of plate, researched the using status of hot straightening machine in our country;(2) Combined with experiment data, the influence of different parameters on low temperature thermal deformation behavior for EH36steel is analyzed;(3) Based on the experiment data under different conditions, the deformation activation energy is calculated, and the Zener-Hollomon parameter equation and sectional flow stress model is established. The fitting relations of initial stress, peak stress, steady state stress, peak strain, and dynamic shape factor are gived;(4) The relevant mathematic model of plate straightening is established, including rolling reduction, residual curvature and residual stress, elastic modulus, bending, plastic strain rate in longitudinal fiber layer and straightening force model, etc.Based on the above research work, the relevant mathematical model of plate heat straightening is established. The result provides a theoretical reference to realize the production of homebred and advanced straightener.