Portable Hardness Tester Methods for Metal Hardness Detection

A portable hardness tester is a handheld, manually operated instrument suitable for on-site or small workpiece direct testing.

The American Society for Testing and Materials (ASTM) has specifically established a standard, numbered ASTM E110-82(1997). This instrument and method meet special needs and are adopted by countries worldwide. Domestically, TX has introduced and developed a series of portable Rockwell hardness testers, with several models currently available for users in China to choose from. Here, a brief introduction to the instruments and methods is provided.

Principles and Instruments

There are various models of portable hardness testers available for Brinell, Rockwell, Vickers hardness testing. The definition of hardness values, indenters, and test forces are the same as those in bench Brinell, Rockwell, and Vickers hardness testing methods. The difference lies in the application of force: Bench-fixed instruments use weights applied to a lever mechanism, with the lever amplifying the force applied vertically to the test sample; another method uses a motor-driven piston in a hydraulic cylinder to apply force, with a pressure gauge determining the force value applied to the test sample. The test methods in ASTM E110-82(1997) for all portable hardness testers do not use the conventional force application methods of fixed instruments.

Portable hardness testers employ two force application methods: one uses a manual screw to apply force to a calibrated spring, with the spring displacement indicated on a dial to achieve the predetermined test force; the other uses a manual operation to pressurize a small hydraulic cylinder (similar to the manual jack principle), with a pressure gauge displaying the test force. A spring release valve on the hydraulic cylinder is used to accurately control the test force by adjusting the spring release valve and pressure gauge indicator (commonly used in portable Brinell and Vickers hardness testers).

There are two indicators on the portable hardness tester. One dial indicates the application of test force by measuring the spring's displacement; the other dial or screw micrometer indicates the indentation depth, reflecting the hardness value.

Testing Operation

Select the Rockwell scale and indenter

According to the type, condition, and thickness of the material being tested, select the Rockwell scale and indenter.

Check the starting pointer position

Check the starting pointer position on the indicator dial, which should point to the dot on the dial. If not, adjust the dial to point to this position.

Apply the preliminary test force

Slowly turn the handwheel to point the dial needle to the "SET" scale.

Apply the main test force

Turn the handwheel to gradually point the needle to the main test force position, carefully aligning the needle accurately with the required test force scale value.

Remove the main test force

Turn the handwheel in the opposite direction of applying the main test force to return the needle to the "SET" scale.

Read the hardness value

Use a magnifying glass to finely read the hardness value on the drum of the screw micrometer. This value represents the indentation depth differential after applying the main test force while maintaining the preliminary test force position. Ensure that the application of test force is balanced and does not exceed the specified preliminary and main test forces. Complete removal of the main test force should be done within 2 seconds after its application.

Instrument Calibration

The instrument can only be used when the test force, loading device, and measurement device have all undergone calibration checks. These checks should be performed prior to the instrument leaving the factory.

Instruments in use should be periodically checked for measurement error on a standardized hardness block using comparison methods. Measure five points on the standard block, take the average value, and ensure it matches the labeled value of the standard block, with an error not exceeding ±1 unit.

Hardness testers should be calibrated once a year (preferably by the manufacturer), holding a valid calibration certificate to perform measurement and reporting of data.

Joanna Zhao

Hi, I'm Joanna Zhao, the Import & Export Manager of Shenyang TX Testing Instruments Inc. I've been with TX Testing for 15 years, gaining hands-on experience by closely observing the production process and personally assembling and testing our portable hardness testers. This has deepened my technical understanding and strengthened my confidence in the industry's development. With this foundation, I provide professional support, feasibility analyses, and customized solutions to meet diverse customer needs, offering one-stop services that ensure efficiency and satisfaction.