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The hot ductility was measured for a series of steels containing Nb and/or Ti with Gleeble-3500 thermo-mechanical simulator.It is found that the effect of austenitizing temperature on hot ductility of Nb-containing steel is significant.As the austenitizing temperature rises up,the shape of embrittling curve (SEC) from V-shape gradually changes to U-shape,and the range of embrittling temperature widens out and the embrittling degree deepens.The SEC of Nb-containing steel is U-shaped and the embrittling temperature range is about 600-1050℃.The initial temperature of embrittlement on the right is nearly independent of carbon content.The SEC of Ti-containing steel is N-shaped and two lowest points are at about 600℃ and the A-F transformation temperature.The SEC of Nb-Ti-containing steel is basically the superposition of two shapes mentioned above.The crack on straightening in continuous casting belongs to intergranular fracture,and the crack on rolling (crack expansion) belongs to transgranular fracture.
The hot ductility was measured for a series of steels containing Nb and / or Ti with Gleeble-3500 thermo-mechanical simulator. It is found that the effect of austenitizing temperature on hot ductility of Nb-containing steel is significant. As the austenitizing temperature rises up, the shape of embrittling curve (SEC) from V-shape gradually changes to U-shape, and the range of embrittling temperature widens out and the embrittling degree deepens. The SEC of Nb-containing steel is U-shaped and the embrittling temperature the initial temperature of embrittlement on the right is nearly independent of the carbon content. The SEC of Ti-containing steel is N-shaped and two of the lowest points are at about 600 ° C and the AF transformation temperature. SEC of Nb-Ti-containing steel is basically the superposition of two shapes mentioned above. Crack on straightening in continuous casting belongs to intergranular fracture, and the crack on rolling (crack expansion) belongs to tran sgranular fracture.