Here are several common ways to determine if a long screw is hardened？

Release time：2020-01-16 18:44 Browse：

1. Surface Appearance: Hardened screws often have a darker or metallic-gray color, especially if they have undergone heat treatment or coatings like Dacromet or Ruspert.

2. Magnet Test: Hardened screws, especially high-strength ones (e.g., Grade 12.9), are usually strongly magnetic.

3. Spark Test (technical): When ground on a wheel, hardened steel produces bright, branching sparks, while mild steel emits dull, short sparks.

4. Hardness Testing: Using a Rockwell or Vickers hardness tester can accurately measure surface and core hardness.

5. Bend or Snap Test (informal): Regular screws tend to bend, while hardened screws are more brittle and may snap under pressure.