Pipeline steel crack propagation resistance testing method

The invention discloses a method for testing crack propagation resistance of pipeline steel. The method specifically comprises the following steps: at a middle part of steel pipe, cutting an improvedDWTT sample in the circumferential direction of the steel pipe, machining a notch in the improved DWTT sample in a linear cutting mode, and forming a back groove in the middle of the back of the improved DWTT sample in a linear cutting mode, adopting the high-strength and high-toughness steel for filling, and marking scale marks between the notch and the back groove after the steel pipe is polished to be smooth; finally, carrying out a DWTT test, collecting a load-displacement curve and a load-time curve of the hammer head in the test process, carrying out the high-speed camera shooting, and acquiring effective DWTT energy. According to the method, the steady-state propagation speed of the cracks is 200 m/s or above, is consistent with a full-size blasting test and is far higher than the propagation speed of the c