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首页> 外文会议>International Pipeline Conference >MODIFIED WEST JEFFERSON BURST TEST FOR ASSESSMENT OF BRITTLE FRACTURE ARREST IN THICK-WALL TMCP LINE-PIPE STEEL WITH HIGH CHARPY ENERGY
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MODIFIED WEST JEFFERSON BURST TEST FOR ASSESSMENT OF BRITTLE FRACTURE ARREST IN THICK-WALL TMCP LINE-PIPE STEEL WITH HIGH CHARPY ENERGY

机译：改进的西杰斐逊爆发性爆破浅骨折管钢脆性断裂钢管爆破爆炸爆裂性能

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Three partial gas pipe burst tests were conducted to assess the brittle-to-ductile transition temperature and brittle fracture arrestability of a heavy-walled TMCP line-pipe steel. This steel had a very high Charpy energy (400 J) which is typical of many modern line-pipe steels. In standard pressed-notch DWTT specimen tests this material exhibited abnormal fracture appearance (ductile fracture from the pressed notch prior to brittle fracture starting) that occurs with many high Charpy energy steels. Such behavior gives an invalid test by API RP 5L3, which makes the transition temperature difficult to determine. The first burst test was conducted in a manner that is typical of a traditional West Jefferson (partial gas vessel) burst tests. The crack was initiated in the center of the cooled vessel (with a partial air gap), but an unusual result occurred. In this test a ductile fracture just barely started from each crack tip, but one of the endcaps blew off. The pipe rocketed into the wall of a containment building. The opposite endcap impacted the wall of the building and brittle fractures started there with one coming back to the center of the vessel. The implication from this test was that perhaps initiation of the brittle fracture in the base metal gives different results than if the initial crack came from a brittle location. The second burst test used a modified West-Jefferson Burst Test procedure. The modification involved cutting a short length of pipe at the center of the vessel and rotating the seam weld to the line of crack propagation. The HAZ of the axial seam weld had a higher dynamic transition temperature. The initiation flaw was across one of the center girth welds so that one side of the initial through-wall crack had the crack tip in the base metal while the other side initiated in the seam weld HAZ. On the base metal side, the crack had about 220 mm of crack growth before reaching steady-state shear area, i.e., the shear area gradually decreased as the fracture speed was increasing. On the other side, a brittle fracture was started in the HAZ as expected, and once it crossed the other central girth weld into the base metal, the fracture immediately transformed to a lower shear area percent. These results along with those from the first burst test suggest that the DWTT specimen should have a brittle weld metal in the starter notch region to ensure the arrestability of the material. The final burst test was at a warmer temperature. There was a short length of crack propagation with higher shear area percent, which quickly turned to ductile fracture and arrested. In addition various modified DWTTs were conducted and results were analyzed using an alternative brittle fracture arrest criterion to predict pipe brittle fracture arrestability.
机译：进行了三个部分气体管突发试验，以评估重型TMCP线管钢的脆性转变温度和脆性断裂性。该钢具有非常高的夏比能源（400 j），这是许多现代线管钢的典型。在标准压制缺口DWTT样本试验中，这种材料表现出异常的骨折外观（来自脆性骨折前的韧性骨折开始，脆性骨折开始），许多高夏比能量钢发生。这种行为通过API RP 5L3提供了无效的测试，这使得过渡温度难以确定。第一个突发测试以典型的西杰斐逊（部分气体容器）突发测试的方式进行。在冷却容器（具有局部气隙）的中心中启动裂缝，但是发生了不寻常的结果。在该测试中，延展性骨折几乎没有从每个裂缝尖端开始，但其中一个端盖吹掉了。管道撞到了一个容纳建筑的墙壁。相对的终点撞击了建筑物的墙壁，并且脆性骨折开始于返回船的中心。该测试的含义是，可能在贱金属中的脆性断裂的引发给出不同的结果，而不是初始裂缝来自脆性位置。第二个突发测试使用了修改的West-Jefferson突发测试程序。修改涉及在容器的中心切割短长度的管道，并将接缝焊缝旋转到裂纹传播线。轴缝焊缝的HAZ具有更高的动态转变温度。起始缺陷在一个中心环焊缝中，使得初始通壁裂缝的一侧具有基础金属中的裂纹尖端，而另一侧在接缝焊缝Haz中引发。在基础金属侧，裂缝在到达稳态剪切区域之前具有约220mm的裂纹生长，即，随着裂缝速度的增加，剪切区域逐渐降低。在另一边，按预期开始在HAZ中开始脆性骨折，一旦将其他中央周长焊接到基础金属中，骨折立即转化为较低的剪切区域。这些结果与第一突发测试的结果表明，DWTT样本应该在起动器凹口区域中具有脆性焊接金属，以确保材料的阻塞性。最终突发测试处于较温暖的温度。较长的裂纹传播长度较高，剪切区域较高，百分比速度迅速转向韧性骨折和被捕。此外，使用各种修饰的DWTTS，使用替代脆性断裂延迟标准进行结果，以预测管脆断裂衰退。

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