YG1600超高强度不锈钢断裂韧性分析及工艺改进

Fracture toughness analysis and process improvement of YG1600 ultra-high strength stainless steel

采用双真空工艺冶炼+锻造成材工艺生产的φ300 mm YG1600超高强度不锈钢,在力学性能检测时发现断裂韧性指标偏低,对断裂韧性指标偏低试样的显微组织进行了金相显微镜及扫描电镜分析,结果表明:沿着断裂韧性试样开裂方向平面存在显微裂纹,裂纹沿着马氏体板条边界开裂且马氏体板条长度在20~80μm之间呈不均匀的分布是导致棒材断裂韧性偏低的原因,在进行了系列工艺分析及工艺模拟后,对原生产工艺进行了调整,真空自耗的熔炼速度由4.85~5.2 kg/min降低到3.8~4.15 kg/min,锻造的末火次加热温度由1100~1130℃降低到1060~1100℃,锻造的末火次锻比由2.25~2.77增加到3.36~4,通过上述调整使YG1600超高强度钢断裂韧性提高了30~40 MPa·m^(1/2)。

For the 300 mm YG1600 ultra-high strength stainless steel produced by double vacuum smelting and forging process,it was found that the fracture toughness index was on the low side during the mechanical property test.The microstructure of sample with low fracture toughness index was analyzed by metallographic microscope and scanning electron microscope.The results showed that there were microscopic cracks in the plane along the cracking direction of fracture toughness sample.The cracks were along the boundary of the martensite lath.The length of the martensite lath was not uniformly distributed between 20-80μm,which was the reason to cause low fracture toughness of the bar.After a series of process analysis and process simulation,the original production process was adjusted.The vacuum arc remelting speed was reduced from 4.85-5.2 kg/min to 3.84.15 kg/min;the last fire heating temperature of forging was reduced from 1100-1130℃ to 1060-1100℃;the last fire forging ratio was increased from 2.25-2.77 to 3.36-4.Through the adjustments above,the fracture toughness of YG1600 ultra-high strength steel increased by 30-40 MPa·m^(1/2).