Study On Metadynamic Recrystallization And Static Recrystallization Behaviors Of Offshore Steel

As an important material of offshore engineering,offshore steel is widely used in offshore platform construction and ship manufacturing.With the development of Chinese marine engineering to the deep sea,offshore steel is often used in the complex and harsh environment of high and low temperature,high pressure and high humidity.In order to ensure the safe and long-term service of steel members in this environment,offshore steel needs to have better properties,especially strength and toughness.Grain refinement can effectively improve the strength and toughness of steel.In view of this,the metadynamic recrystallization and static recrystallization behaviors of low alloy marine engineering steel were studied in this paper.It can realize the grain refinement of steel,effectively improve the strength and toughness of marine steel,and provide theoretical guidance for the preparation and processing of high-performance marine steel.The main research contents of this paper are as follows:(1)Through single pass isothermal hot compression test and metallographic analysis,the effect of thermal deformation conditions on the recrystallization grain size of low alloy marine steel was studied,and the metadynamic recrystallization and static recrystallization grain size models of low alloy marine steel were established.The results show that the recrystallization grain size of low alloy marine steel decreases with the decrease of metadynamic recrystallization deformation temperature and the increase of strain rate.After static recrystallization,the recrystallized grain size decreases with the decrease of initial grain size,the increase of deformation,the decrease of deformation temperature and the increase of strain rate.(2)The effects of different thermal deformation conditions on the recrystallization volume fraction of low alloy marine steel were analyzed by double pass isothermal compression experiment.And the dynamic models of metadynamic recrystallization and static recrystallization of low alloy marine steel were established.The results show that the volume fraction of metadynamic recrystallization increases with the increase of deformation temperature,strain rate and holding time.The volume fraction of static recrystallization increases with the increase of deformation,deformation temperature,strain rate,and holding time.(3)Based on the experimental model,the metadynamic recrystallization and static recrystallization behavior of low alloy marine steel under different rolling conditions were simulated by DEFORM software,and verified by experiments.The results show that: in the rolling process,the metadynamic recrystallization and static recrystallization of alloy marine steel exist at the same time.The recrystallization behavior of marine steel is significantly affected by heating temperature,reduction,deformation temperature and rolling speed.