GB/T 24522-2020 Active National standards

GB/T 24522-2020 Metallic materials—Method of test for the determination of resistance to stable crack extension using specimens of low constraint

Publish Date: 2020-06-02 Implement Date: 2020-12-01 For services related to genuine standard inquiry, procurement, translation, and other related services in China, please Contact Us

Basic Information

Standard Code: GB/T 24522-2020

Standard Type: National standards

Standard Status: Active

is_force_gb: no

CCS Name: \n Test methods for the mechanical properties of metals

ICS Name: Mechanical testing of metal materials

Publish Date: 2020-06-02

Implement Date: 2020-12-01

Pages: 44 pages

Scope

This standard specifies the method for determining the steady-state crack propagation resistance, crack opening displacement δ5, and critical crack tip opening angle Ψc of homogeneous metallic materials with cracks under quasi-static loading. For specimens with notches, compact tensile specimens and central crack tensile specimens, fatigue pre-cracks are introduced and the tests are conducted under conditions of slowly increasing displacement.
The test methods described in this standard cover those specimens that do not meet the size-insensitive requirements for fracture performance, such as compact tensile specimens and central crack tensile specimens with relatively thin dimensions.
This standard provides a method for determining the crack propagation resistance curve (R-curve). Similar to ISO 12135:2002 for determining the fracture toughness characteristic value of compact tensile specimens, the method for determining the fracture toughness characteristic value of central crack tensile specimens is given in Appendix D.
The determination of crack propagation resistance can be carried out using the multi-specimen method and the single-specimen method. The multi-specimen method requires loading multiple nominally identical specimens at different displacements. The crack propagation resistance curve is obtained by identifying the region of tough crack propagation and measuring the amount of crack propagation in the fracture surface. As long as the required accuracy can be met, the single-specimen method based on unloading compliance and electric potential can also be used to measure crack propagation. The recommended single-specimen method is described in ISO 12135:2002. Regardless of the method used, the aim is to obtain enough data points to adequately describe the crack propagation resistance behavior of the material.
The determination of δ5 is relatively simple and straightforward. The δ5 result is represented by the resistance curve, show