[TheForge] Re: 1018

[John Husvar]

Jerry Frost wrote:

> 
> Manganese steel has a few problems you should know about. I don't know about
> toxicity so am no help there. However steels with high percentages of
> manganese have a time/temp limit. This was discussed at hardfacing seminars
> using charts, graphs, etc. to illustrate ratios. Basically, the higher the %
> of manganese, the less time at heat it will stand before failing.
> 
> This was the major determinimg factor in hardfacing crusher drums, etc. as
> you had to keep the drum as cool (below 250f) as possible. There are special
> water bath welding tanks designed specifically for hardfacing crusher drums
> that only expose a couple inches of drum to the air for welding. Passes have
> to be high amp, narrow and FAST to avoid heat sinking in the drum.
> 
> I don't have any of the charts or specific info regarding manganese steels,
> it wasn't applicable to drilling but I do remember how strongly they
> emphasized the time/heat limit and how it is cumulative. Steel of X %
> manganese has X minutes at X temp. before failure. PERIOD.
> 
> Here's the thing that scared me. Once the limit has been exceeded the steel
> WILL fail, the only question is WHEN. Usually it's pretty immediately but
> sometimes it isn't and there's no telling what will set it off. Failing
> crusher drums have killed welders perched on them running beads.
> 
> I have no idea where your blades are on the time/heat curve but they're on
> it. I'm not trying to be an alarmist and this may not apply to AR500 but I
> think I'd tell your supplier/customer high manganese steels are not
> acceptable.
> 
> Frosty

OK, thanks, Jerry. I'll certainly look into that more. I might ask on 
sci.engr.joining.welding too: Those guys seem to know about just about 
every kind of welding and they'll know where to look for more data.

The welds are narrow, fast, and high amp: The stuff won't take a decent 
bead any other way. And I do cool them fairly quickly, usually so I can 
start finish work.:)

As for toxicity, I make sure to wear a mask every time I work with it. 
there are health issues with manganese.

Thanks again. I'll do some more research. And I'll talk it over with the 
customer.

John