Definitions and Representation Methods for Brinell, Rockwell, Vickers, and Shore Hardness

Vickers Hardness (Vickers Hardness)

• Principle: A square-based diamond pyramid with a 136° angle between opposite faces is pressed into the material under a specific load for a defined dwell time. The load is removed, and the two diagonals of the resulting impression are measured using a microscope. The average diagonal length is used to calculate the Vickers hardness number (HV) via a formula or conversion table.
• Characteristics:
  • Unified Scale: A key advantage is the continuous scale from very light loads (microhardness) to higher loads. HV values from different loads are theoretically comparable (e.g., HV10 can be related to HV0.1).
  • Wide Application: The diamond indenter allows testing of very soft materials (e.g., aluminum) and extremely hard materials (e.g., nitrided layers, ceramics) simply by changing the load.
  • High Accuracy: Measuring diagonal length is more precise than measuring indentation diameter or depth.
  • Small Indentation: Considered a minimally destructive test, making it suitable for finished products and thin specimens.
  • Disadvantage: The testing process is relatively slow, requires a skilled operator to measure diagonals, and is less efficient than Rockwell testing.

2. Brinell Hardness (Brinell Hardness)

• Principle: A specified diameter tungsten carbide ball (HBW; hardened steel ball, HBS, is obsolete) is forced into the material under a predetermined load. After the load is maintained for a specific time, it is removed. The diameter of the resulting indentation is measured. The Brinell hardness number (HBW) is then calculated from a formula or found via a table based on the load and the indentation diameter.
• Characteristics:
  • Large Indentation: The high loads create a large surface area indentation. This provides an excellent average value of the material’s bulk properties and is particularly suitable for coarse-grained or heterogeneous materials like cast iron.
  • Data Stability: The large indentation size minimizes the effect of local microstructural variations, leading to excellent repeatability and a result that reflects the material’s true macro-hardness.
  • Highly Destructive: Not suitable for finished goods or very thin specimens due to the large, permanent impression.
  • Limitation: Not suitable for very hard materials (typically >650 HBW), as the ball indenter itself can deform, compromising the result’s accuracy.

3. Rockwell Hardness (Rockwell Hardness)

• Principle: This method uses a two-stage loading process:
  1. A minor (pre) load (typically 10 kgf) is applied to seat the indenter and establish a reference position (zero point).
  2. A major (main) load is then applied and held for a set dwell time, forcing the indenter deeper.
  3. The major load is removed, while the minor load is maintained. The material recovers slightly from elastic deformation. The permanent increase in depth of penetration (*e*), from the initial pre-load reference point to the final position under the pre-load, is measured. This depth difference is converted to a Rockwell hardness number (e.g., HRC). A larger depth difference means a softer material (lower number).
• Characteristics:
  • Rapid Operation: The hardness number is read directly from a dial or digital display immediately after the test. No optical measurement is needed, making it the fastest method, ideal for high-volume production quality control.
  • Multiple Scales: By combining different indenters (diamond cone or balls of different sizes) and major loads, various scales (HRA, HRB, HRC, HR15N, HR30T, etc.) are created to cover a wide range of material hardnesses.
  • Non-Unified Scales: This is the major drawback. The scales are arbitrary; a value of 60 on the HRA scale represents a completely different hardness than 60 on the HRC scale. They cannot be directly compared.
  • Lower Relative Accuracy: Measuring depth is inherently less precise than measuring length (diagonals/diameter). Results are also more sensitive to surface finish and flatness.

4. Shore Hardness

The measurement principle of Shore hardness involves pressing a specific-shaped indenter into non-metallic specimens such as plastics, rubber, and glass under defined conditions to form an indentation depth, which is then converted into a hardness value.
Example notation: Shore A/15:70 indicates a Shore A tester used to indent the sample for 15 seconds, yielding a Shore A hardness value of 70.
Shore hardness applications: It employs four scales (indenters):
A indenter is suitable for general-purpose rubber, synthetic rubber, soft rubber, polyesters, leather, wax, etc.
D indenter: Suitable for high-hardness rubber, resins, acrylic, glass, thermoplastic rubber, printing plates, fibers, etc.
AO indenter: Suitable for low-hardness rubber, rubber-plastic blends, sponge.
AM indenter: Suitable for thin specimens of ordinary hardness.

Hardness | Hardness Testing | Hardness Test Methods | Brinell Hardness | Rockwell Hardness | Vickers Hardness | Superficial Rockwell Hardness | Shore Durometer Test | Hardness Conversion Table | Brinell Rockwell Hardness Conversion | Carbon Steel Cast Steel Hardness Conversion | Rockwell Superficial Brinell Vickers Shore Hardness Conversion | Harder Scales Equivalent | Softer Scales Equivalent | Figure Comparing Hardness Scales | Table of Components Showing Relevant Surface Hardness Values | O-Ring Installation Compressive Load vs Hardness Shore A Scale | Detect Hardness