A Crack Recognition Technology of Nodular Cast Iron Fracture Toughness JIC Specimen

Abstract

A kind of identification process of the fracture toughness JIC sample crack of ductile iron, described specific steps are as follows: Step 1, the ductile iron sample is placed in the heating apparatus that contains air atmosphere and heat treatment, and temperature is 340-360 ℃, and holding time is 0.8-1.2h; step 2, cooling the heat-treated nodular cast iron sample to room temperature, breaking the sample on a breaking instrument to obtain a ductile iron fracture sample; step 3, placing the broken nodular cast iron fracture sample on the tool Under the microscope, the crack line is identified according to the color boundary of different regions. According to the crack identification process of the ductile iron fracture toughness JIC sample provided by the invention, the rapid and effective identification of the crack of the ductile iron sample after the fracture toughness JIC test can be realized, which can lay an important foundation for obtaining the fracture toughness performance parameters of the ductile iron in the later stage. Provide important data support for the application of ductile iron in the fields of wind power and nuclear power.

Description

technical field [0001] The invention belongs to the technical field of detection of fracture mechanical properties of metal materials, and in particular relates to a process for identifying cracks of ductile iron fracture toughness JIC samples. Background technique [0002] Ductile iron is known as the "terminator" of cracks. With its excellent strength and corrosion resistance, simple production process and equipment, and low cost, it has been widely used in engineering, especially in the fields of wind power and nuclear power. Fracture toughness J IC It is an important anti-fracture index of materials and a key parameter for safe service of engineering materials. Therefore, the fracture toughness of ductile iron before engineering service J IC Conducting test evaluations is of great significance. [0003] Fracture toughness J IC The principle of the test is to carry out quasi-static loading on the sample, and use the test instrument to continuously record the load i...

AI Technical Summary

Problems solved by technology

For materials with a homogeneous structure, the fracture toughness J IC Each part of the front end of the crack of the sample is always in the same two-dimensional stress state. Under the action of stress, slip lines are generated at each part of the front end of the crack at the same time, and then the crack is formed and spreads forward. The crack line is left, and the distance between the crack line and the sample loading line is the sample crack length, which can be easily read under a tool microscope, or through general "bluening" treatment (ie 200-300 ℃ heat treatment) can also be effectively identified, but for some special materials with uneven structure or coarse grains, such as ductile iron, direct observation under a microscope is not feasible

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