what is the comparative hardness of metals?
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  1. #1
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    what is the comparative hardness of metals?

    Cold rolled steel is only "5" on the Moh's scale. Copper is a lot softer. But what is the hardness ?

    Brass is 3.5 and glass is 5.5, harder than CRS.

    Stainless steel must be a lot softer than CRS, and cutting it may be closer to cutting copper than CRS.

    Just brain storming.

    On the other hand, i was trying to grind through a 5/8 square lathe tool bit, cut it in half on a cut-off saw (grinding disk) and could not get through it.

    On the Moh's scale talcum is 1 and diamond is 10.

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    Alot of metals are judged on 2 different scales all judges by how far either a ball (brinnel Hardness) or a diamond (rockwell hardness) penetrates into its surface. Now each scale has different sizes. Brinnel has different size balls and maybe wieghts. Rockwell uses different wieghts. And of course there is a shore scale for plastics and the like, softer materials. Hope this enlightens you a little.
    Toad

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    The Mohs scale isn't linear and so isn't a very useful way to compare materials that have slightly different properties. 7075 T-6 aluminum is slightly harder than mild steel but mild steel would be assigned a higher hardness on the Mohs scale as it will scratch the aluminum. The difference between 9 and 10 on the mhos scale is much larger than the difference between 3 and 4 so comparisons aren't easy. It's based on scratch testing and has very limited usefulness in metalwork.

    That's why we use other scales such as the Rockwell, Vickers and Brinell scales.


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