Less wear resistant steels

[PJones]

We make machines that strap large objects with steel wires. The wire is zinc coated. The wire slides over some of our machine parts and snaps across them as the wire gets pulled tight.

Originally the parts were made from 1020 and hard-chrome plated. Once the wire wore through the plating, the underlying material wore away quickly. Subsequent parts were made from 304 - this eliminated all wear but brought on the wrath of the accountants due to material costs and the loss of the spare parts business.

The shapes of the parts don't lend themselves to the more aggressive hardening methods. Carburizing them curls them up into spirals.

So, I am looking for suggestions for a material that has LESS wear resistance than 304 under these conditions but obviously more than 1020.

I'm looking at 17-4 and some of the duplex stainless steels. Does anyone have other suggestions?

Thanks.

 

[TVP]

There are a number of lower cost austenitic stainless steels, such as 301, 201, 204 (Nitronic 30), and a variety of proprietary designations (see link below). Duplex stainless steels will have higher wear resistance than Type 304. Have you investigated lower temperature processes like salt bath nitriding of 1020? This should not cause distortion unless there are considerable residual stresses in the pieces prior to coating.

http://www.euro-inox.org/htm/p_109_EN.html

 

[PJones]

Great! I will look into this.

We did look at nitriding these parts in the past, but didn't pursue it. I will have to track down someone and ask why.

Thanks.

 

[iainuts]

I wonder what was more of a concern, the cost of 304 or the loss of the spare parts business. If the former, and assuming 304 had lower wear resistance for some reason (I'm finding that hard to believe) then you could simply put a weld overlay on the 1020. Weld wire is generally 308 but if 304 worked, I have to believe 308 will be roughly the same. You might even consider Stellite weld overlay if you want a very hard, abrasion resistant surface.

If on the other hand, the accountants are concerned about loss of the spare parts business, point to the strategy the US car manufacturers used a few decades ago. Putting your product out with parts designed to wear out at predictable intervals is not good for business. If that's really the case, shame on them.

 

[EdStainless]

The 304 holds up because the surface work hardens to ridiculous levels.
I also believe that there is a level in hell for those that think that 'planned obsolescence' is a viable business strategy.

If yo look at nitriding try to develop a surface that gradually gets softer the deeper you go. This way the wear will gradually increase and at least the user will have some warning before all hell breaks loose.

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