Yield stress from tensile test and yield stress from hardness tests

Thread starter mh1985
Start date Mar 21, 2012
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Hardness Stress Tensile Tensile test Test Yield Yield stress

In summary, yield stress from tensile test is a measure of the stress at which a material begins to deform plastically, while yield stress from hardness tests is determined by measuring the indentation hardness of a material and correlating it to yield stress using empirical relationships. Both methods have their own advantages and disadvantages in determining yield stress, and yield stress values from both methods are used in designing and selecting materials for engineering applications. Factors such as material type, test method, and equipment calibration can affect the accuracy of yield stress measurements from both methods.

Mar 21, 2012

mh1985

Why can there sometimes be a difference observed between them?

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Mar 21, 2012

Mech_Engineer

Science Advisor

Gold Member

Because a hardness test is a highly nonlinear test which is only able to approximate yield strength of the material using some loose relationships.

1. What is the difference between yield stress from tensile test and yield stress from hardness tests?

The yield stress from tensile test is a measure of the stress at which a material begins to deform plastically. It is determined by applying a gradually increasing tensile force to a material until it reaches its yield point. On the other hand, yield stress from hardness tests is determined by measuring the indentation hardness of a material using a standardized test method, such as the Rockwell or Brinell hardness tests. This value is then correlated to the material's yield stress using empirical relationships.

2. Which method is more accurate in determining yield stress?

Both methods have their own advantages and disadvantages. Tensile tests provide a direct measurement of yield stress, but they can be time-consuming and require specialized equipment. Hardness tests, on the other hand, are quicker and easier to perform, but they rely on empirical correlations and may not be as accurate for all types of materials.

3. Can yield stress from hardness tests be used as a substitute for yield stress from tensile test?

In some cases, yes. Yield stress from hardness tests can be a good estimate of the yield stress from tensile test for certain materials, such as metals. However, it may not be accurate for other materials, such as polymers, where the relationship between hardness and yield stress may not be well-defined.

4. How can yield stress from tensile test and yield stress from hardness tests be used in engineering applications?

Yield stress values are important parameters in designing and selecting materials for various engineering applications. They can help determine the maximum load a material can withstand before it begins to deform plastically, and can also provide information about the material's ductility and strength. Yield stress values from both tensile and hardness tests can be used in conjunction with other mechanical properties to make informed decisions about material selection and design.

5. What are some factors that can affect the accuracy of yield stress measurements from both methods?

The accuracy of yield stress measurements can be affected by several factors, such as the type and condition of the material being tested, the test method used, and the expertise of the person performing the test. It is important to follow standardized testing procedures and ensure proper calibration of equipment to obtain more accurate results.