Carburizing grades 1

[Badplaid]

A customer of ours is carburizing 5120 (C-0.17-0.23, Mn-0.60-0.90, Cr-0.70-0.90) steel plate 3/8" thickness to a 60-62 Rc. That grade, in the volumes they need, does not exist domestically....they would need to buy a year's worth for one mill run.
I thought of the possibility of subsitituting a A514 Grade B chemistry (very common grade and easy to get...and much cheaper) in the non-heat treated form as a replacement, which they can then case harden after forming and welding:
A514 Grade B
C-0.12-0.21
Mn-0.70-1.00
Cr-0.40-0.65
Mo-0.15-0.25
V-0.03-0.08
Ti-0.01-0.03
B-0.0005-0.005

What problems or pitfalls might be expected? How much of their process will have to change? Is this a good idea? Metallurgically, I dont see much of an issue, however, I am not a heat treater and could be missing something.

Any help is appreciated.

Alex

 

[Metalguy]

Like you, I don't see any problem with this approach.

 

[TVP]

I agree with Metalguy as well. I was waiting for Carburize to answer, as he is an expert on this subject.

 

[Carburize]

I ran a case depth simulation and both steels perform about the same - I estimated an effective case depth of 0.030-inch for the 5120 and under the same conditions 0.026-inch for the A514. The only concern I have is a potential for very low core toughness in the A514 and before committing a lot of parts I would run a sample through a carburize cycle and do a few Charpy tests just to check.

 

[Badplaid]

I appreciate the help! The customer plans on running some trials as soon as we get them a few plates...some of guys there are pretty skeptical, but without giving me a reason. Core toughness isnt as much of a concern as the case hardness and depth and cost. The part is under pretty low stress and mainly sees abrasion from slurry. The parts have to be formed and welded and attached to 8620 bracketry before the entire units see the carburizing cycle. They moved away from 8620 plate to 5120 for cost and now the mill supplying the 5120 has declined unless they get 200+ tons and even then, the price will go up significantly. Going this new route could reduce their steel costs by 40%...thats before taking account the costs associated to holding a year's worth of steel.

We'll see...I am laid off as of next week (the powers that be dont think that ideas like this provide value anymore) so it's going to be out of my hands...for 40% cost savings, you'd think they would want to figure out a way to make it work. If I find out how the trials go, I'll let you know.

Thanks again for the help.
Alex

 

[toolsteelmet]

Since both the carbon & the chromium appear to be slightly lower in the grade you want to substitute, you might find a somewhat shallower depth of case, and perhaps a somewhat lower heat treated hardness in the matrix. You might look into 8620, which is also commonly available, and which has a little nickel to assist in hardenability.

 

[MBHUTCHENS]

Alex,
Sorry to hear about the layoff.
Been there, done that, several times the past 5 years.
Lots of companies these days are just cutting people to stay afloat and can't support any efforts that can reap major returns - short term is beating out long term everywhere.
Anyway, try the US Government USAJOBS.OPM.GOV - Materials Engineering is Series 0806, but General Engineering 0800 works just as well. Give it a little time.
I really enjoy my new job at Defense Logistics Agency.
Good luck and God bless.
Matt