20CrMnTiH齿轮钢连铸坯表层纵裂的热模拟研究

通过Gleeble-1500热模拟机研究了20CrMnTiH齿轮钢(mm):150×150、180×220、220×300连铸坯600～1300℃的强度和塑性。试验结果表明,3种铸坯在650～950℃真实断裂强度S_k很低,在950～1200℃随温度升高S_k增加,超过1200℃时S_k降低;该钢的第2脆性区为950～700℃,增加连铸坯出结晶器坯壳厚度,降低950～700℃区间停留时间,有利于防止裂纹源扩展成纵裂纹。

A Study on Heat Simulation of Surface Longitudinal Crack of Gear Steel 20CrMnTiH Concasting Billet

The strength and plasticity of (mm) 150 x 150, 180 x 220 and 220 x 300 concasting billet of gear steel 20CrMnTiH at 600 ~ 1 300 °C have been studied by Gleeble-1500 thermal simulation machine. Test results showed that the actual strength at fracture S_k of three size of billet at 650 ~ 950 °C was very low, at 950 ~ 1 200 ℃ the S_k increased with increasing temperature, then the S_k decreased at temperature higher than 1 200 °C ； the second brittle zone of steel was at 950 ~ 700 ℃. It is available to prevent crack source evolving into longitudinal crack by increasing the shell thickness of billet out of mold and decreasing holding time at 950 ~ 700 °C zone.