Isotropic pyrolytic graphite ultrasonic detection defect grading evaluation method

Abstract

The invention provides a method for carrying out nondestructive detection and quality grading evaluation on isotropic inclusion defects in an isotropic pyrolytic graphite workpiece by utilizing ultrasonic waves, which provides a reference test block for quality grading evaluation, and nine groups of vertical through hole artificial defects with different numbers are processed on the reference block. Different numbers of vertical through holes are used for simulating the looseness degrees of different degrees, the reference test block is used for making a looseness degree change representationcurve, and the mechanical property indexes of samples with different looseness degrees are tested, so that the corresponding relation among the reference test block, the looseness degrees and the product quality is established. And finally, the isotropic inclusion defects can be divided into different quality grades by referring to the reference test block, so that the application requirements canbe met, and the utilization rate of the product can be increased.

Description

technical field [0001] The invention relates to the field of ultrasonic nondestructive testing, and provides a defect classification and evaluation method for ultrasonic detection, which is used for isotropic inclusion defect detection and quality classification evaluation in isotropic pyrolytic graphite. Background technique [0002] Isotropic pyrolytic graphite is an excellent high-performance mechanical seal material and structural material, because of its good mechanical properties, self-lubrication, sealing, wear resistance, corrosion resistance and fatigue resistance, etc. There are important applications in fields such as aerospace and ships. In the process of product preparation, due to fluctuations in process conditions, defects such as inclusions and pores may appear in local areas of the material. The most common type of defect is isotropic inclusion defects. It is a loose structure that will be to a certain extent The mechanical properties of the product are red...

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Problems solved by technology

[0004] In order to solve the above problems, the present invention provides a method for grading and evaluating defects in ultrasonic detection of isotropic pyrolytic graphite parts. The method provides a comparison test block for quality grading and evaluation, and nine groups of For the artificial defects of vertical holes with different numbers, use different numbers of vertical holes to simulate different degrees of porosity, use the comparison test block to make a characteristic curve of the change of porosity, and test the mechanical performance indicators of samples with different degrees of porosity, so that Establish the corresponding relationship between comparative test block-porosity-product quality

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