High Temperture Thermoplastic Behavior of BTW1 Steel Continuous Casting Slab

Abstract

For a steel factory production of BTW1 continuous casting slab is taken as the research object， and high temperature thermoplastic test is carried out by Gleeble 3800 thermal simulation testing machine.The tensile fracture is observed and the microstructure is analyzed by metallographic microscope and scanning electron microscope.The test results show that the reduction of area of BTW1 steel decreases first， then increases and again decreases with the increase of heating temperature. The reduction of area reaches the highest value of 68.3% at 1 000 ℃ and only 29.23% at 950 ℃. The reduction of area of BTW1 steel is lower than 40% in several temperature ranges， and the high temperature thermoplasticity is very poor， the crack sensitivity is strong.When the heating temperature is lower than 800 ℃， the thermoplasticity is poor due to the absence of MBIP and DRX， and the fracture morphology shows the coexistence of plastic deformation and brittle fracture. When the heating temperature is lower than 800 ℃， there is no microband induced plasticity and dynamic recrystallization， resulting in poor thermoplasticity， plastic deformation and brittle fracture coexist；When the heating temperature is 950 ℃， the DRX phenomenon increases， but the mixed crystal structure leads to a decrease in plasticity， and the fracture morphology is typical brittle fracture. When the heating temperature is 1 000 ℃， the DRX process is obvious， and the uniform fine grain region is formed， and the fracture is typical dimble morphology. When the heating temperature is 1 100 ℃， a melting zone appears in the fracture， but part of the dimpled structure remains at high temperature.

Keywords

• btw1 steel； continuous casting slab； high temperture thermoplastic； reduction of area； dynamic recrystallization