The title is more general than my particular question, in particular I bought a "allen key" and it broke after doing a lot of force with it trying to turn a hard screw. In order to get a harder tool I need to know the material of this one. Tell me how to test if this allen key is chrome vanadium. If i should weight it, measure volume thus density, and this picture:

broken allen The other broke like this, it deformed:

deformed allen key, because forcing

I want to be also a little educated on this topics: probably the tool is chrome vanadium but of low quality, or maybe it is extremely expensive or hard to test for me if the new tools I bought are of another material and if it's harder than the broken ones, the new ones are chrome vanadium and "stanley" (a corporation).

  • $\begingroup$ I think if they were of chrome vanadium steel, they wouldnt have broke or deformed. I made like 50 kg force of force. I'm not a chemist. $\endgroup$ Jan 10, 2016 at 20:55
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    $\begingroup$ You need a key that is both tough (deforms rather than shatters) and strong (does not bend easily). To some extent, these qualities conflict with each other. BTW, often a tight bolt can be removed by an impact wrench, or a quick snap of the key... the same is true of the lug-bolts of a car wheel. $\endgroup$ Jan 11, 2016 at 23:03

1 Answer 1


You can tell by the dark gray appearance that it is not vanadium chrome, but rather an alloy of hardened steel. If it were made of vanadium chrome, it would not have broken, and it would also have a silver appearance to it. Density may help tell if you are close, but with alloys the density does not necessarily conform to the rule of mixtures.

  • $\begingroup$ How do you know if have not broken? What would have happened, bended? $\endgroup$ Jan 10, 2016 at 22:57
  • $\begingroup$ Would have likely stripped the hex-hole out $\endgroup$
    – A.K.
    Jan 10, 2016 at 23:31

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