Measuring method for surface strengthening member fatigue crack expansion rate

Abstract

The invention provides a measuring method for a surface strengthening member fatigue crack expansion rate. The method comprises the following steps: sample preparation is carried out, and hardness, a microscopic structure size, distribution of a residual stress in the length direction along the height direction of a sample are measured; an optical observation platform is erected, crack length changes of two sides of the sample during the test process are observed and recorded; a load less than a yield limit is applied to the sample for test, when the crack length expansion amount exceeds an appointed length every time, the test is paused, the cracks are shot and the current load and loading cycles are recorded; the test data of the sample is subjected to analysis and processing, and the fatigue crack expansion rate of the member is obtained. In the measuring method, a sample is cut from a whole-size member directly, and the consistency of the sample and the member is kept. The problems are solved effectively that whole-size member test time is long, the material cost is high, a lot of test data is difficult to obtain, and measuring of the surface strengthening member fatigue crack expansion rate is achieved.

Description

technical field [0001] The invention relates to the field of material mechanics, in particular to a method for measuring the fatigue crack growth rate of a surface gradient strengthened component. Background technique [0002] Fatigue failure is one of the key mechanical problems of load-bearing components. Fatigue damage often originates from the surface of components, so it is a common method to improve the overall fatigue performance of components through surface strengthening. For components strengthened by quenching, a strengthening layer will be formed on the surface, and there will be a large residual compressive stress, and the internal matrix material will have a small tensile stress, and there will be a transition layer between the strengthening layer and the matrix. In fact, the microstructure and mechanical properties are characterized by gradient changes from the surface to the matrix. For homogeneous material components, the traditional crack growth experimen...

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Problems solved by technology

Full-scale component experiments cannot obtain a large amount of experimental data due to time and cost factors

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