Rockwell hardness tester is one of the commonly used hardness testing instruments in the industrial field. It evaluates the hardness of materials by measuring the depth of indentation, and has the characteristics of easy operation, fast testing speed, and minimal damage to the sampleWidely used in industries such as metal processing, mechanical manufacturing, automotive, aerospace, etc.

　　1、 Measurement principle of Rockwell hardness tester

The basic principle of Rockwell hardness testing is to use a diamond cone indenter with a vertex angle of 120 °, press it into the surface of the specimen under the specified test force, maintain it for a certain period of time, and measure the depth change of the indentation to calculate the hardness value.

The testing process is divided into two steps:

1. Preloading (initial test force): Apply a small force (usually 10kgf) first to make contact between the indenter and the surface of the specimen and eliminate the gap.

2. Main loading (total test force): Apply the main test force again to further press the indenter into the material. After a certain period of time, remove the main test force and only retain the initial test force. Measure the residual depth (e) of the indentation, and calculate the hardness value from this depth.

The calculation formula for Rockwell hardness value (HR) is: HR=N - (e/C)

Among them, N and C are constants (such as N=100 or 130, C=0.002mm), and e is the change in indentation depth.

　　2、 Main purpose

The Rockwell hardness tester is mainly used for rapid detection of the hardness of metal materials and is suitable for the following scenarios:

1. Hardness testing of metal materials

① Steel materials: such as carbon steel, alloy steel, stainless steel, etc., commonly using HRC or HRB rulers.

② Nonferrous metals, such as copper, aluminum, and their alloys, typically use HRF or HRB scales.

③ Quenched steel and hard alloy: use HRC ruler.

2. Heat treatment process control: After metal heat treatment, this instrument can quickly detect whether the hardness meets the requirements, ensuring that the material performance meets the standards.

3. On site testing and quality control: The instrument is easy to operate and does not require the preparation of complex samples. It can be directly tested on the surface of the workpiece and is suitable for production lines, mechanical maintenance, material acceptance, and other scenarios.

　　3、 Common Rockwell hardness scales

The Rockwell hardness tester has multiple scales, suitable for materials with different hardness ranges:

1. HRA (Diamond indenter, 60kgf): Used for high hardness materials.

2. HRC (diamond indenter, 150kgf): commonly used, suitable for quenched steel and tool steel.

3. HRB (steel ball indenter, 100kgf): suitable for soft steel, copper alloy, and aluminum.

4. HRF (steel ball indenter, 60kgf): Suitable for softer non-ferrous metals.

　　4、 Advantages

1. Fast testing speed: Measurements can be completed in just a few seconds, suitable for batch testing.

2. Easy to operate: No complex calculations required, read hardness values directly.

3. Small indentation: minimal damage to the sample, suitable for finished product testing.

4. Wide applicability: By replacing the pressure head and load, various materials can be tested.

summary

The Rockwell hardness tester is a crucial hardness testing tool in the industrial field, widely used for hardness assessment, heat treatment process control, and quality control of metal materials due to its fast, simple, and reliable characteristics. Whether in the laboratory or on the production site, it can provide efficient and accurate hardness data to assist in precise control of material properties.