D406A钢焊接接头断裂韧度测试

Fracture toughness tests of D406A steel welded joints

根据英国标准BS7448断裂韧度试验标准,采用多试样法,测试了D406A超高强度钢焊接接头的J-R曲线。取尺寸为B(板厚)×2B、缺口方向为板厚方向、带预制疲劳裂纹的标准试样进行三点弯曲试验。测试试件焊缝和热影响区的载荷—施力点位移曲线,从而得到J积分。然后对数据点进行拟合得到J-R曲线,计算出J积分临界值,从而解决了由于板厚不足而无法直接测试焊接接头临界应力强度因子的问题,为固体火箭发动机壳体设计提供依据。

In accordance with the fracture toughness test standard of BS7448,J-R curve tests were conducted with multiple specimen with welded joints of D406A ultra-high strength steel.According to the standard,the specimen with prefabricated fatigue crack has a standard 3 points bending shape that has a rectangular section of B×2B(B: specimen thickness) and notch orientation of thickness direction.The load and load-line displacement of weld and heat affected zone were tested,and the values of J integral were calculated.Finally,J-R curves and the critical value of J were obtained through the data points best fitted.Thus the problem of failure to test the critical stress intensity factor in welded joints directly by lack of thickness of specimen was coped with and the reliable evidence was offered for the design of solid propellant rocket engine.