Bright Mild Steel vs Black Mild Steel

[Anonymous]

The discussion is really about the difference between cold drawn materials and hot rolled, or formed, materials, not just Bright MS versus Black MS.

Out of idle curiosity I've just taken a 6" length of ½" square bright drawn mild steel and milled 1.4mm off one side. As far as I could tell the material was straight (rule and backlight) before I started. Afterwards it was clearly bowed away from the machined edge. The material was bowed about 5 thou at each end.

Andrew

[vintagengineerParticipant @vintagengineer]

I wonder if normalising the steel first will relieve the stresses?

[JasonBModerator @jasonb]

Yes it does, Andrew also mentioned it earlier.

[Philip RoweParticipant @philiprowe13116]

I often have wondered if the age of the material has any effect on this bowing characteristic inasmuch that over time any locked in stress has been able to work itself out. The majority of my material stock steel, brass, copper etc is in the order of 50 – 60 years old, the last stock I bought was some brass angle and that was at least 10 years ago.

I'm not a massive user of milled stock but it is an issue that personally I have not encountered but do recognise that it does happen.

Phil

[not done it yetParticipant @notdoneityet]

often have wondered if the age of the material has any effect

Not sure about BMS, but certainly large engine castings were left to "weather" (often for several months(?)), back in the earlier decades of the last century.

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