Optimized Production Process Research On Automobile Beam Plate P510L

Combining the item"optimizing the production process of automobile beam plate P510L", thermal simulation experiment, rolling experiment in the lab and industrial-experiment were carried out respectively in this paper through P510L steel.The deformation resistance of P510L steel during the hot deformation, microstructure evolution behavior of austenite grain during the static recrystallization, continuous cooling under undeformed and deformed conditions were investigated by means of the compression deformation test using MMS-200 thermomechanical simulator, the continuous cooling transformation(CCT) curves of undeformed and deformed austenite were established through thermal dilation measurement and microstructure observation. Effect of controlled rolling and controlled cooling on microstructure, mechanical properties and cold formability of P510L steel was studied by rolling experiment in the lab. Effect of deformation parameters and cooling process after rolling on microstructure, mechanical properties and cold formability of P510L steel was studied by industrial experiment.The conclusion was summarized as follows:(1)The true-stress-true-strain curve of P510L steel mainly takes recovery and recrystallization as characteristic. Static recovery completely occurs after the tested steel is deformed at 1050℃, more recrystallized austenite grains begin to appear in the microstructure when 50 seconds preserving heat behind 850℃deformation. So the strain of finish rolling passes can be accumulated as long as finish rolling temperature and the pass reduction are controlled appropriately in the course of finish rolling of hot tandem rolling.(2)Phase transition area consists of proeutectoid ferrite area, pearlite area and bainite area in the static CCT curve and the dynamic CCT curve; deformation enlarges proeutectoid ferrite area and pearlite area, retards bainite transformation; austenite transformation changes at different cooling speed.(3)Uhder the condition of the same rolling schedule, cooling mode and coiling temperature, elongation of the tested steels rises with the decrease of the beginning temperature of finishing rolling; when the beginning temperature of finish rolling is 1010℃, those adopting two-stage cooling process under the conventional rolling schedule have higher elongation and lower yield ratio; under the conditions of the same finish rolling beginning temperature, cooling mode after rolling, coiling temperature and product thickness, the average ferrite grain size and the pearlite are smaller, the tested steels have higher strength and elongation through multiple passes rolling.(4)Lowering V and adding Nb with the content of other elements unchanged, the mechanical properties of the tested steels reach the technical requirement of P590L through controlled rolling and controlled cooling; through the process of fore-stage cooling and coiling at 600℃, the mechanical properties of P510L can also reach the technical requirement of P590L under the condition of industrial experiment.