Wear and Stainless Steel

[smslab]

I would be grateful if anyone could contribute from his/her experience to the following. We have a wear problem.....using 304 stainless steel sheet, we have a part that slides back and forth on it, and small rock dust particles get in between the urethane block and the 304. There are crosswise welds that become abraded rapidly. Once they are gone the rest of the structure doesn't last long. It would seem to me that a 17-4 PH could be an answer. I know, hardness isn't everything, but at least you can get RC40. If we get the sheet in the SHT condition, weld, and then age to H900 we shouldn't get too much distortion. Any words of wisdom (other than suggesting Hastelloy or Haynes Stellite) would be greatly appreciated.

 

[mcguire]

Wear resistance doesn't increase with hardness when the strengthening mechanism is precipitation, so forget PH grades. You can use a martensitic grade like 410, or you can use a less stable austenitic grade that transforms easily to martensite. A 301 with 17 max chrome and 7 max nickel should help.

 

[TVP]

Why is the component stainless steel? Perhaps you could use a more conventional steel alloy along with a suitable surface treatment to impart the necessary wear resistance and corrosion resistance. The ferritic nitrocarburizing process is one such process. The following link provides more information:

http://www.finishing.com/kolene/qpq/index.html

Otherwise, if you have to have stainless steel, then mcguire's suggestion for changing to a martensitic grade like 410 is a good one. You can obtain more information using on this grade using the following links:

http://www.aksteel.com/pdf/markets_products/stainless/martensitic/410_Data_Sheet.pdf

http://www.alleghenyludlum.com/pages/products/PDF/mart400.pdf

http://www.cartech.com/

(click on Technical Information then Alloy Category, then Stainless Steels, then Martensitic Stainless Steels then Carpenter Stainless Type 410 for product info)

 

[smslab]

Thank you for your suggestions. I had in fact wanted to go with 410 or similar, but there is a problem with distortion. We have to weld the sheet after it has been bent. The part length is 22'. If we then try to quench and temper afterwards we'll have huge distortion problems.

 

[GRoberts]

There is not normally a need to Q&T 410 stainless after welding. Especially on thin sheet. A simple stress relief PWHT is usually adequate. On thin sheet, the slow cooling that takes place after welding may in itself be enough. This would usually need to be verified based on your specific application though. If there is a specific reason you have to Q&T after welding please let us know.

 

[smslab]

The reason I was wanting to Q&T after welding is that we are going for hardness as a way to comabt a wear problem. The sheet has to be formed, as a matter of fact is has to be bent around a 3/8" radius. Then it is welded. I would think that if 410 is in a hard condition we might not be able to form.

 

[mcguire]

After hearing more I still think a lean 301 would be ideal. You could form martensite in situ by shot blasting and harden whatever area you wanted. It is also weldable.
If you want this material, go to a stainless re-roller like Ulbrich, Somers, or Rodney( Allegheny, now). They use a lot of it for high tensile stainless.

 

[rolledalloy]

You might take a look at a duplex stainless steel such as 2205 (26Rc). This alloy has a slightly higher hardness level than 304SS. Its hardness is in the annealed condition so no heat treatment would be necessary. Not a huge jump, but might be enough to improve the reliability of the part without going through too much trouble with heat treatments, etc.

 

[bngreene]

If the 304 sheet is not wearing, it seems that the relative
roughness of the weld metal is catching some particles and
allowing galling or other form of wear to take place. If that is correct, could you adjust the weld procedure and have the welds ground flush?

 

[MadMango]

304 is very easy to gall as Bngreene has pointed out. What's the hardness of your urethane blocks? You might wnat to consider a self-lubricating material for your block, like Delrin, Turcite X, or similar.

http://www.interstateplastics.com/meta/fmtur.htm

"The attempt and not the deed confounds us."

 

[smslab]

I'm back with my wear problem, older and wiser.
We decided to do some lab tests to see if we could find any differences in abrasive wear resistance between 301 1/4 hard (candidate material), 304 (current material) and 17-4 PH H900 (candidate material) with and without weldments. The 301 1/4 hard was marginally better than the other two.
Now we are convinced that while stainless has the advantage from the point of view of the customer not thinking the part is ugly because it is covered with rust, it just plain has miserable wear resistance.
These parts are 0.050" thick bent sheet 22' long, welded crosswise every 10', so we are very concerned about distortion during heat treatment. Does anyone have a suggestion for a replacement material? An earlier post had a suggestion to use a convenional steel and then nitrocarburize, but the size and shape of the parts suggests to me that this might be impractical.