[TheForge] Re: 1018

[Jerry Frost]

----- Original Message -----
From: "John Husvar" <jhusvar@neo.rr.com>

Subject: Re: [TheForge] Re: 1018

>
> Speaking using suitable steels for a purpose:
>

>
> He said it was something called AR-500, burnouts from sheets and plate.
>
> Looked up AR 500 via Google: I think I've found the problem. It's an
> abrasion-resistant, 11-14% manganese, work-hardening steel used for
> lining rock crushers, dump truck beds, etc, etc, stuff you'd want to
> last a while under abrasion.
>
> Well, it works as advertised. :)
>
> What this stuff'll do to a grinding wheel or belt shouldn't happen to
> Saddam. Not to mention what it'll do to a smith. Thank Bog for dust masks.
>
> Are there any significant dangers in using this stuff for replica battle
> axes, halberds, spearheads, etc? I haven't been able to break any of
> these things, even by beating the heck out of 'em with an 8-pounder.
> Some buyers do use some of the smaller ones for throwing contests.
>

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
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.