selecting best grade of stainless steel 1

[cvg]

I'm trying to specify stainless steel bars (3/4" or 1" diameter, hex or square x 18" long) to be used in an abrasive environment as a survey monument. They will need to be welded and very hard to resist erosion. I'm looking at cost, availability and workability. Specifically 303, 304 and 316. Which would be the best?

 

[Ron]

cvg...don't cross post! But since you asked , 304L or 316L will work for this. Both weldable and corrosion resistant.

 

[cvg]

I know, I know - I cross posted because I got no response from this forum. Thanks anyway

 

[MikeMet]

Austenitic stainless steels, such as 304, 316, have very low erosion resistance. They have corrosion and velocity accelerate corrosion resistance, but no hard particle erosion resistance because they are soft so they are a bad choice for pure erosion resistance. I

Hardness for erosion resistance and welding are arch enemies of each other, as typically very hard things are not easily welded due to cracking problems.

Given that, if the weld will be out of the erosion zone and you need some corrosion resistance, you could harden the surface of stainless steel by nitriding, flame spray with a hard coating or weld overlay with hard coating. You could also use a solid bar of something like Stellite 6 which is hard, erosion resistant and can be welded to other parts

 

[cvg]

then given that stainless steel is softer than carbon steel, I would rather go with a high strength carbon steel instead of stainless. I don't particularly care about rust, mainly hard particle erosion. I am thinking ASTM A572, Grade 65 steel bars would be better.

 

[SJones]

Since this is for a 'survey monument', would you care to elaborate on the specifics of the erosive environment that is of so much concern?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[cvg]

spillway below a dam, will be flowing water periodically and including sand and gravel. A flat plate will be welded to the top and they will be anchored in the concrete slab. The will need to be more resistant to erosion than the proposed high strength concrete.

 

[Ron]

cvg...that's a pretty abrasive condition. Even A572 will polish out under that. You might want to consider "hiding" the monuments behind an upstream ledge or guard or depressing them below the slab surface with a pipe protection ring or similar.

 

[cvg]

I'm hoping the plate which will be 1/2" A572 steel will protect the bar. The top of the plate will be flush with the concrete. If we observe during annual inspection that the plate and concrete are being eroded away, we can replace the plate.

 

[arunmrao]

How about CA6NM ,it is a grade of martensitic stainless steel and can withstand erosion. Many parts for hydro electric turbines are made of this material.


If you think education is expensive, try Ignorance.
- Andy McIntyre


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[cvg]

It seems that stainless steel is softer, so would this really be more resistant to erosion than high strength carbon steel?

is CA6NM readily available to an earthwork contractor and weldable? The project involves earthwork and concrete only, no hydro-electric so I am not sure our contractor will be able to readily aquire this material. How much are these monuments going to cost?

 

[arunmrao]

CA6NM grade is weldable,but popularly used in cast form. Near equivalent in plate forms could be 400 series. These are also weldable.


If you think education is expensive, try Ignorance.
- Andy McIntyre


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[EdStainless]

I would suggest that you consider 2205. It is a duplex SS and much harder than 300 series grades, it is also more corrosion resistant.
I hate to say it but under your condition there are only a few fairly exotic metals that would hold up.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[IRstuff]

Is this application that different than the standard survey monument that gets full weather plus cars driving over them on occasion?

TTFN

FAQ731-376

 

[IRstuff]

For that matter, why can't you use the same materials used for manhole covers and other covers found on city streets?

TTFN

FAQ731-376

 

[arunmrao]

cast iron? Only problem cannot be welded.


If you think education is expensive, try Ignorance.
- Andy McIntyre


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[cvg]

way more abrasive than city streets

 

[arunmrao]

cvg,you must try 400 series material. Perhaps you can try it on a small area,convince yourself and then go full blast. the economics and technical requirements are met. they can be hardened,machined or welded and are available in all basic forms as rods,bars,plates etc.


If you think education is expensive, try Ignorance.
- Andy McIntyre


_____________________________________

 

[arunmrao]

Can you reconsider making your monument in granite or marble and then cementing it in a recess.


If you think education is expensive, try Ignorance.
- Andy McIntyre


_____________________________________

 

[dik]

Specifically 303, 304 and 316. Which would be the best?

I wouldn't use any of those and if it is used as a monument, I would specifically design it to have a screwdown cover either with a threaded cap or with flat head screws.

I would use AISI 431 which I often use for high strength anchor rods (from my General Notes):
HIGH STRENGTH ANCHOR RODS SHALL CONFORM AISI 431 AND ASTM A276 HAVING A MIN FY = 95 KSI (655 MPA) AND A UTS = 125 KSI (860 MPA) OR APPD EQ

I've attached an outline of the material (I'm not sure of the source, but you can use it to further search.)