Hardness Conversion Calculator

Hardness Conversion: A Complete Guide to Hardness Scales and Conversion Charts

In materials science and manufacturing, hardness is a crucial property that determines a material’s resistance to deformation, scratching, or penetration. Since there are multiple hardness scales—such as Brinell (HB), Rockwell (HR), Vickers (HV), and Mohs—it is often necessary to convert values from one scale to another for comparison or specification.

This guide explains the key hardness scales, how to convert between them, and provides conversion charts for practical reference.

🔍 What Is Hardness?

硬度 is defined as a material’s resistance to permanent shape change when a force is applied. It’s not a fundamental physical property, but an empirical measure obtained using standardized test methods. The higher the hardness, the more resistant the material is to indentation or scratching.

📏 Common Hardness Scales

1。 Brinell Hardness Number (BHN or HB)

Uses a steel or tungsten carbide ball to indent the material.

$$\text{BNN}=\frac{2磷}{\mathrm{au}D（（D-\sqrt{D^2-d^2}）}$$\text{BHN} = \frac{2P}{\pi D (D – \sqrt{D^2 – d^2})}

在哪里：

• $磷$

  : load (kgf)

• $D$

  : diameter of the ball (mm)

• $d$

  : diameter of the indentation (mm)

2。 Rockwell Hardness (HR)

Measures the depth of penetration under a standard load using different scales:

• HRB: For softer materials (brass, copper alloys).

• HRC: For harder steels.

3。 Vickers Hardness (HV)

Uses a diamond pyramid-shaped indenter and is suitable for very small or thin materials.

$$\text{高压}=\frac{\mathrm{<span\; class="tr\_"\; id="tr\_48"\; data-source=""\; data-orig="1.854">1.854</span>}<span\; class="tr\_"\; id="tr\_49"\; data-source=""\; data-orig="\cdot ">\cdot </span>F}{d^2}$$\text{HV} = \frac{1.854 \cdot F}{d^2}

在哪里：

• $F$

  : load (kgf)

• $d$

  : average diagonal length of the indentation (mm)

4。 Mohs Hardness

A qualitative ordinal scale from 1 (talc) to 10 (diamond), used mostly in geology.

📐 Why Convert Hardness?

Each testing method and scale has its own testing conditions and applicability. Conversion is necessary when:

• Specified hardness is in a different scale.

• Comparing materials tested by different standards.

• Translating lab results into manufacturing specs.

🔄 Hardness Conversion: General Chart

Below is a general reference chart showing approximate conversions between common hardness scales. Note: These are empirical conversions and should be used as a guide only.

🔧 Online Hardness Conversion Formula (Example)

For certain materials like 钢, approximate conversion formulas can be used.

Rockwell C (HRC) to Brinell (HB) for Steel:

$$\text{HB}\approx 10<span\; class="tr\_"\; id="tr\_91"\; data-source=""\; data-orig="\cdot ">\cdot </span>\text{HRC}<span\; class="tr\_"\; id="tr\_92"\; data-source=""\; data-orig="+">+</span>50$$\text{HB} \approx 10 \cdot \text{HRC} + 50

例子：
If HRC = 40

$$\text{HB}\approx 10<span\; class="tr\_"\; id="tr\_95"\; data-source=""\; data-orig="\cdot ">\cdot </span>40<span\; class="tr\_"\; id="tr\_96"\; data-source=""\; data-orig="+">+</span>50=\mathrm{<span\; class="tr\_"\; id="tr\_97"\; data-source=""\; data-orig="450">450</span>}$$\text{HB} \approx 10 \cdot 40 + 50 = 450

Always validate conversion with a standard chart or testing when precision is required.

🧪 Real-World Applications

✔️ Metal Manufacturing

Steel mills may report hardness in HB, while end users require HRC.

✔️ Quality Control

Parts are tested using portable testers (Rockwell), but specs require Vickers or Brinell.

✔️ Materials Selection

Engineers compare different materials using equivalent hardness values.

💡 Tips for Accurate Hardness Conversion

• Always refer to official conversion tables (ASTM E140 is the U.S. standard).

• Use the same material type when comparing (e.g., steel, copper, aluminum).

• Avoid converting near the limits of any scale, where accuracy drops.

• For precise applications (e.g., aerospace), convert by re-testing instead of using charts.

🧰 Code Example: Hardness Converter in Python

def hrc_to_bhn(hrc):
    """
    Approximate HRC to Brinell for steel only.
    """
    if 20 <= hrc <= 60:
        return 10 * hrc + 50
    else:
        raise ValueError("Valid HRC range: 20–60")

# Example:
hrc_value = 40
bhn_value = hrc_to_bhn(hrc_value)
print(f"{hrc_value} HRC ≈ {bhn_value} HB")

📚 Summary

📝 Final Thoughts

Understanding hardness conversion allows manufacturers, engineers, and researchers to work seamlessly across different industries and standards. While approximate formulas and charts provide quick references, official standards and retesting are the most reliable methods.

✅ 记住: All conversions are material-dependent. Always verify with the actual standard or test result for critical applications.