Research on High Temperature Mechanical Properties of Nb-Ti-V Microalloyed Steel for Ship Plate

High temperature mechanical properties of continuously cast slabs of D36 steel for ship plate were tested by Gleeble-3500 thermomechanical simulator.The morphology of its fracture surface was analyzed by SEM,and its brittleness mechanism was also studied.The results showed that: the brittleness temperature range Ⅰ of the 373# steel slab containing no vanadium was over 1 350 ℃.In the range of 1 350～950 ℃,the slab has a reduction of area over 80% with good high-temperature plasticity.The brittleness temperature range Ⅲ of the specimen was 950～600 ℃ with its reduction of area in the range of 41.7% ~64%.The brittleness temperature range Ⅰ of the 374# steel slab containing vanadium was from melting point to 1 250 ℃,which exhibited good high-temperature plasticity at 1 250～950 ℃.Its brittleness temperature region Ⅲ was 950～600 ℃with reduction of area of 34%~73%.In order to prevent cracking during straightening,the straightening temperature for the slabs should be controlled over 950 ℃.