A Method for Obtaining the Uniaxial Stress-Strain Relationship of Materials by Small Punch Test

Abstract

The invention discloses a method for obtaining uniaxial stress-strain relation of a material through a small punch test. After a continuous load-displacement curve of a stamped wafer sample is obtained, power-law fitting is conducted on the stage III of the P-V curve, obtained load characteristics and displacement indexes are introduced to a Hollomon equation so as to obtain the uniaxial stress-strain relation of the material. The method is suitable for ductile and power-law isotropic hardening materials, the uniaxial stress-strain relation of the material can be obtained only by cutting out a small wafer sample from an existing member in special circumstances such as high temperature and irradiation, and accordingly the degradation properties of the material are assessed. The method has weaker destructiveness on the existing member, achieves the micro-damage detection, sample processing and testing principles are simpler, obtained results have higher accuracy, the shortcoming that a traditional uniaxial drawing test is largely limited by material size and the like is overcome, and the cost lower. The method has the greater advantages in testing of precious-metal servicing micro-force materials establishing constitutive relation of minimally invasive wafers and other small samples.

Description

technical field [0001] The invention relates to the mechanical performance testing technology of ductile materials, especially the mechanical performance testing field of rare and micro-scale materials and service component materials. Background technique [0002] In petrochemical, nuclear power, aerospace and other fields, there are a large number of components serving under high temperature, high pressure, irradiation and other conditions. With the growth of time, the materials will inevitably undergo creep, oxidation, corrosion and other phenomena, resulting in material degradation and damage, how to evaluate the reliability and safety of materials is of great significance. The traditional method is to conduct non-destructive testing or sampling tests on service components. Non-destructive testing can detect the uniformity and micro-defects of the structure, but it cannot quantitatively give many mechanical performance parameters of the material, such as yield strength, t...

AI Technical Summary

Problems solved by technology

The process of the traditional method is cumbersome, and the accuracy of the obtained results is not high

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