| This paper contains two parts: The study of the cutting section metallographic method and the study of dynamic fracture toughness and arrest performance of the 5NiCrMoV steel:It is well known, the J integral is very important in elasticity-plastic fracture mechanics . In the condition of static and quasi-static, JIC used to represent the Initiation fracture toughness of materials. Therefore, the Ji value of the accurate Initiation fracture toughness has very important significance in the actual application. Regarding JIC obtaining, the traditional test method is determining the relations curve of the J integral and the crack extension Δa (the JR curve), The point of intersection of the JR curve and blunting line is defined as the Ji value of apparent initiation fracture toughness . This stipulation is relatively reasonable for middle and high strength steel . But in the testing of fracture toughness of the good plastic toughness material (hull steel, pressure vessel steel and nuclear electricity steel and so on ), the method of traditional resistance curve of many specimens shows unappropriateness. This paper research the initiation toughness of several kinds of steels using cutting section metallographic method.Through cutting section metallographic method, under - 20 °C conditions,we get : The initiation toughness Ji value and δi value of 4# test specimens of 10Ni5CrMoV steel are 323.77KJ/m2, 0. 177mm respectively; The initiation toughness Ji value and 5 i value of 6# test specimens of 10Ni5CrMoV steel are 243. 44KJ/m2, 0. 165mm respectively. The initiation toughness Ji value and 5 i value of 1# test specimens of 10Ni3CrMoV steel are 592.58KJ/m2, 0.395mm respectively; he initiation toughness Ji value and 8 i value of 3# test specimens of 10Ni3CrMoV steel are 442. 81KJ/m2, 0. 380mm respectively. We can see the validity of Ji value with cutting section metallographic method between comparison of the testing result of Ji of 10Ni5CrMoV steel with...
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