What is the most available chemistry for large cross section? 2

[salmon2]

We have or have tried three options as below:

1) 8630 Modified to higher alloy addition
2) 4340 or 4330V is unacceptable because of NACE 0175
3) just began to consider F22/F22V, not sure availablility yet.

Therefore, we only have one option which is 8630MOD right now, and it is great except availability. So any comments on above items or other ideas are highly appreciated.

Basically our design requirements include:

1) Diameter range: 10.0' ~ 14.0'.
2) NACE 0175 Part 2, therefore 22HRC max
3) as high as possible for YS, 80 or 85ksi preferred
4) Q&T condition because of low temperature CVN required
5) Off the shelf because of really low volume, just several hundreds of pounds each PO

 

[Maui]

What is the application? What are the specific application requirements for the part that you are you making? Your question cannot be answered without sharing this fundamental information.

Maui

http://www.EngineeringMetallurgy.com

 

[stanweld]

You indicate the diameter 10 to 14 feet. Do you mean inches? Is this an oil field tubular component?

 

[salmon2]

Maui,

Sorry about that. It is used for oil and gas downhole tools, CNC machined parts all the time. The threemajor industry standards are API 6a, iso13628 and nace0175/iso13628. They are seeing up to 350f temperature, very high pressure, 10 or 15 ksi, and millions pound of tension possibly. The common material format is really thick tube, t/D up to 30+%. So we have to get bar stock then machine the core portion or rough-out machining then re-heat treat them. 1st approach is preferred (it is why I asked this question) as it is quicker.

The reason for low volume is because we are in prototype right now, but even in later production, our volume wont be anywhere even close to mill runs.

Any more informations I can provide, please let me know. This supposes to be a gerenal question as we have many parts having availability issue, not just one or two parts.
Actually we have 4th option:
4) martensitic 410, but concern about price and galling.

 

[salmon2]

stanweld, terribly sorry, should be inches

 

[stanweld]

8620/8630 has been a mainstay alloy in your stated service for decades. Other alloys capable of meeting 22 Rc max. in the normalized and tempered or quenched and tempered condition are 4130 & 5130.

 

[salmon2]

8630 is fine if it is available. 4130/4140 is shy for my size.

 

[metman]

Have you looked at Boron steel? I don't know if one would meet your rqmts but I know that Catepillar uses a fair amount of Boron steel because hradenability (depth of hardness) is good compared to richer alloys at less cost.

 

[salmon2]

Not yet, metman. I learned before that Boron is a very strong hardenability agent especially for low carbon steel through working with a Japanese steel mill. They are enthuastic about Boron and actually they developed it, I think.

I have two concerns about Boron steel: 1) I suspect that its harnability can be close to 4140 at most, so not enough for our sizes; 2) it will be too special, therefore, its availability will be pretty limited. But I will definitely take a closer look as my Timken handbook got a 86B30 chemistry.

The global market for our products is tiny - therefore, we don't and won't have a industry standard to address our material need. As stanweld said 8620/8630 is a major alloy being used. But actually what we have found out is that 8630MOD is the best and standard 8630 is still a bit off.

 

[redpicker]

There is a bearing manufacturer that sells a modified 4130 chemistry specifically aimed for improved IMPACT properties. The 10"-14" diameter is where you are going to have trouble. I don't know many steel mills that can roll bar that large so you are probably going to have to look at forgings. If you go the forging route, you can probably get nearly any chemistry you want, provided you are willing to buy an entire heat. Even a small heat is going to be 10-30 tonns. If you can find a warehouse that has some large OD IMPACT7 (9.5 - 10 inch), you may be able to get an open die shop to upset some of that to ~14". It won't be very long, but at a couple of hundered pounds, it doesn't need to be.

rp

 

[salmon2]

rp, I think you meant Timken. Yes, their IMPACT series is a very good fit for our purpose. Their 9CR1MO seems good too, but just we can't afford an entire heat and the half year lead time associated with mill runs.

Open die forging is a good idea. We have been looking at close die forging to get us to the close dimension for some expensive nickel alloys and then heat treatment, final machining, etc, whcih takes a long time. Open die forging absolutely is another manufacturing route for us, thank you very much.

 

[PaulDoherty]

Be sure to consider Scot Forge if you are looking at open die forging. They are also very good with rings, which it sounds like may be usefule to you.

http://www.scotforge.com/sf_materials.htm