Metal cutting ( wire ) and material Burn 2

[farzadtb]

Hi All

Does anyone have an experience , when you cutt a steel wire mechanically, the cut is done by shear, in which part of it is ductile deformation and from some point we have britle cut, is it possible that a part in the cut surface get a very high temperature and burn ?? I mean change color ?

 

[1gibson]

If you cut it with a torch, yep. If you cut it with an angle grinder, probably. If you cut it with tin snips, no.

Explain your entire situation, what do you really expect as an answer to that vague question?

 

[farzadtb]

Very sorry , you were right 1Gibson , I edited my question

 

[CoryPad]

Adiabatic shear causes high temperature, but those conditions are not present in most situations with shearing metal wire.

 

[farzadtb]

How could I verify if my case was adiabatic , and if I assume it is , what is the solution ? What should I do ? there is a guess that also the reason of that local color change is oxidation , is this also possible ? like an imperfection or defect ? but the thing is it was repeated in many cases in the same place

 

[Compositepro]

Heating sufficient to cause color change simply does not happen during shearing.

 

[farzadtb]

Are there parallel hypothesises apart from heating ? or you'd say it's only adiabatic ?

 

[gruntguru]

An "adiabatic" system is thermally insulated (which would then allow a small amount of heat to raise the local temperature significantly). Metals are never good insulators so adiabatic heating is not possible.

je suis charlie

 

[farzadtb]

Thank you , so if Adiabatic heating is not the case ,what could be the color change , that to me sounds very much like an over heating

 

[someguy79]

How big is this wire? For common, small wire sizes, I wouldn't expect to see color change due to heating when cut by mechanical, non-abraisive methods. However, for large sizes, you may be accumulating heat from deformation of the material. That could drive up the metal temperature near the cut pretty high, at least in theory.

I've never seen that due to practical considerations. It's just much easier to cut really thick stuff by other means (saw, cutting wheels, etc.) rather than a single cut with a shearing operation.

An interesting parallel might be to look at chips from a lathe or mill operation. These often turn from greyish steel to tan, gold, brown, and blue. However, the way heat builds on this has more to do with cumulative effects of cutting on the workpiece and heating of the cutting tool.