X70海底管线低温断裂韧性试验研究

Research on Low-temperature Fracture Toughness of X70 Submarine Pipeline

根据BS7448断裂韧性试验标准,对国内自主研发的X70海底管线钢管管体及焊接接头的低温(0℃)裂纹尖端张开位移(CTOD)进行断裂韧性试验,并对其阻力曲线及断口形貌进行了研究分析。结果表明:0℃下管体的CTOD值大于焊接接头,且管体横向略大于管体纵向;熔合线+5 mm位置试样的CTOD值接近管体横向;焊缝、熔合线及熔合线+2 mm位置试样的CTOD值相对较低,易产生突进或失稳现象,是断裂韧性最薄弱的部位。

The problem of submarine pipeline fracture toughness was analyzed. In accordance with the BS7448, CTOD （crack tip opening displacement） tests were conducted at 0℃ for the pipe body and welded joints of X70 submarine pipeline. The resistance curve and fracture morphology were analyzed. The results show that the CTOD on the pipe body is higher than that of on the welded joint at 0℃, and the CTOD value on transverse body is slightly larger than that on the longitudinal body. The CTOD on FL （fusion line）＋5 mm is closed to transverse body. The CTOD on the weld, FL and FL＋2 mm is low relatively, which can cause the phenomenon of pop-in or instability which are the weakest positions for the fracture toughness.