# Hss - How Corrosion Resistant Is It?



## Riaan (Oct 29, 2015)

Hi guys,

This afternoon after graft I went to browse around in a nearby tool shop, they sell allsorts including some machine tooling, guages and the like. The tooling and other fragile things are stored in cabinets with locking glass sliders, you know the type. A great deal of their stock is Chinese in origin.

Anyways, they had a selection of HSS tool bits, painted blue with ground contact surfaces. The ground, bare sections were absolutely crimson with rust. This sort of surprised me since the molybdenum alloy tool blanks I've "inherited" have been laying in a box for decades and they dont have a single speck of corrosion on them and are mirror smooth.

What gives? Are the bits in question inferior or is it the nature of the beast for certain types of high speed steel alloys?

Thanks!
Riaan


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## T Bredehoft (Oct 29, 2015)

I'd avoid and (HSS) steel that rusted for tooling, I agree that the decades old tool bits in my tool boxes have no rust on them.


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## kd4gij (Oct 29, 2015)

Are you sure they where HSS ? I haven't seen HSS painted.


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## joshua43214 (Oct 29, 2015)

hmm, not sure paint really sticks to HSS any better than it sticks to SS.

None of my HSS tolling has any rust, even the stuff that has sat untouched outside a box for years is rust free. I am pretty sure it gets a patina and stops oxidizing


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## Riaan (Oct 30, 2015)

kd4gij said:


> Are you sure they where HSS ? I haven't seen HSS painted.



Dunno. After doing some googling for images, I deduce that they probably are brazed carbide bits. I couldnt handle them since they were locked away but they are similar to these.




Except what I suppose are the carbide tips were rusted. And badly so. There was no bling on them at all.

So let me modify my original question - how corrosion resistant is carbide?


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## kd4gij (Oct 30, 2015)

A lot of times the import tools like that are shipped with cosmoline like coating that when dried is a rust color.


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## stupoty (Oct 30, 2015)

I only get the occasional little spot of rust on my hss bits and blanks. 

Stuart


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## planeflyer21 (Oct 30, 2015)

kd4gij said:


> A lot of times the import tools like that are shipped with cosmoline like coating that when dried is a rust color.



And twice as difficult to clean as rust.


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