Surface hardening on Stainless Steel Fasteners

[mechdesignandmanuf]

I am making stainless fasteners with XM-7 or 304HQ stainless but need higher strength and hardness. Has anyone had any experience using the SAT12 hardening process on fasteners or some equivalent process ?

 

[unclesyd]

I have never seen the process used on fasteners.
You will improve the surface hardness but will not gain very much if overall tensile strength using the SAT 12.

There are several approaches to getting a higher strength fastener. First would be to roll the the threads if the fastener is under 1.25". The next would be to use a higher strength material with similar corrosion resistance.

What are your sizes?

 

[CoryPad]

What is the end use? Do you need higher surface hardness, or do you need higher overall strength? These are two different factors.

 

[mechdesignandmanuf]

couple of sizes, the Shank is 4mm or 6mm, they are thread rolled already.

It would be nice to get increased surface hardness and some strength too.

Already pre-drawing the material to increase strength, but need more without loss of corrosion resistance.

Kind of between a rock and a hard place, as usual.

 

[EngAddict]

Add more bolts..

What load are you after per bolt and what standard are you using for load capacity?

 

[MintJulep]

What happens when your special fasteners are replaced during maintenance with regular ones?

 

[CoryPad]

You should consider the Bumax products from Bulten. They have strong grades (Bumax 88 and 109) and a hard grade (Bumax Hard).

http://www.bufab-stainless.se/eng/index.htm

 

[mechdesignandmanuf]

Thanks CoryPad,

Bumax 109 and Bumax 120 look interesting, but so far have not found out what actual materials or processing they use...seems proprietary.

 

[CoryPad]

I didn't read your original post closely enough. Bulten would be your competitor and not likely to share information. Perhaps you need to do some competitive analysis.

 

[EdStainless]

I would suggest that you look at using 2205 or a similar duplex grade. You may still need to pre-cold draw but these alloys start with higher strengths.

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