A Method of Obtaining Mechanical Properties of Metal Materials Based on Load-Depth Curve

Abstract

The invention discloses a method for obtaining the mechanical property of a metal material based on a load-depth curve and belongs to the technical field of material property test. On the basis of determining to adopt a large pressed depth ratio (the depth h / the radius R of a pressing head), three kinds of engineering materials, namely alloy steel, aluminum alloy and titanium alloy, of which the elasticity modulus has remarkable difference are treated respectively by adopting two depth combinations (h1=0.1R and h2=0.4R) so as to obtain the respective material property coefficients; a ball factor S which reflects a hardening index effect is introduced so as to obtain a relational expression among a dimensionless function, W / (h3sigmarS ) and E* / (sigmarS); and the mechanical property of a tested material can be finally determined through constitutive relations, obtained by simulation by adopting finite element values, between the coefficients and the materials. By the method, the obtained result is more accurate; and the method is easy and quick and applicable to engineering structural materials in accordance with the power law.

Description

technical field [0001] The invention belongs to the technical field of testing methods for mechanical properties of materials, and specifically relates to a method for obtaining yield strength, work hardening index and tensile strength mechanical properties of metal structural materials based on a load-depth curve (P-h curve). Background technique [0002] The current general-purpose nano-indentation test technology is also called depth-sensitive indication indentation test technology. The test method is to press the pointed cone or spherical indenter into the surface of the material to be tested, and continuously record the loading and unloading of the indenter. The load and displacement data in the process can be used to obtain the load-displacement curve (P-h curve) of the tested material. By establishing a suitable mechanical model, a variety of mechanical parameters can be tested, including hardness, elastic modulus, fracture toughness, stress-strain curve, storage modu...

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Problems solved by technology

2) When using the spherical indentation method based on representative strain to evaluate material properties, two different depths are generally used. The maximum depth currently used is generally less than 0.3R, but even if the depth reaches 0.3R, two different materials cannot be separated correctly. performance (such as Figure 4 For the two materials, the curves are coincident when h<0.3R)

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