Experimental Study on Deep Notch Fracture Characteristics of Q420qE Bridge Steel

Deep notch wide plate tensile test and conventional tensile test are conducted on 20 mm-thick Q420qE steel in temperature range of -80~20℃. Results indicate that with the decreasing temperature, the fracture strength R_f increases, the fracture strain e_f remains almost the same, and the deep notch fracture strength R_n decreases. A modified Neuber formula is proposed to describe the relationship between R_n, R_f, e_f and the temperature. The deviation between R_n calculated by the proposed formula and tested by deep notch wide plate tensile test is within ±5%, indicating that for deep notch wide plate tensile test, the decrease of temperature may increase the concentration of stress and strain due to the presence of the deep notch.