5160 Scorched?

bobbywett

bobbywett

Joined
Jul 23, 2006
Messages
1,231
Hi Everyone,

Today I put a large bowie in my paragon oven for a 2 hour temper cycle. I was shooting for 360F degrees, but in my haste pressed the wrong program. Long story short, the blade spent 2 hours at 2000F degrees.

Is there any hope of salvaging this piece or should I chalk her up to learning!

Thanks for your time,

Bobby

Sent from my iPhone
 
What type of metal? If a simple hi-carbon steel, just call it normalized/annealed and start all over. If stainless...... I'll let other folks comment on that. Sandvik says more than one heat treatment is NOT good.

Ken H>
 
Ken H> said:
What type of metal? If a simple hi-carbon steel, just call it normalized/annealed and start all over. If stainless...... I'll let other folks comment on that. Sandvik says more than one heat treatment is NOT good.

Ken H>
Click to expand...

I would venture to say that 2000 for 2 hours is far to high an long to consider it normalized or annealed. I would think there would likely be significant grain growth from that cycle at the very least.
 
The steel is 5160, not HC, but carbon spring style steel. I know that 2000 degrees is approaching forge welding temperatures. I'm wondering in the soak at that high a temperature was too much? From what I understand about 5160, is it is forgiving...but probably not that forgiving?
 
You probably have done no harm to the steel. It has large grain structure, and most likely a good layer of decarb .... that's all. If the blade was ground close to final size, then the decarb layer may be problematic, but if there are a few thousandths of extra metal to remove in final clean-up, you should be OK.


Run it through a full grain refinement series to reduce the grain size - 1625°F, 1550°, 1350°, and 1250°. Quench after the first three, but not after the 1250°. Then do the austenitization and tempering as you originally planned.
 
Hey Stacey,

It was ground close to final size. I left .025 -.030 over the length of the entire edge. As a mater of fact, some of the edge was starting to deteriorate. I placed the edge profile on my sander using 220 grit to bring it back to .030.

The scale coming off of the blade is quite large and reminds me of potato chips. That's how big they appear.

So if I understand you correctly I should quench the blade twice, once after the 1350 cycle and once after bring her back up to critical say 1525 or so. Then I should temper as usual. NO QUENCH after the 1250 heat cycle?

Is there still enough carbon in this blade? I believe that this steel is considered a hypouticoid contain as much carbon as say 1084-1095?


Thanks for your input... Appreciated greatly!

Bobby
 
since you have already ground it to close to your final dimensions just quench it three times from 1525 then temper as normal. it will turn out just fine.
 
Since the blade is at final size, and there isn't a lot of spare metal, you probably will be better off going with Bill's regime. Don't grind off the existing scale. You can soak it in vinegar overnight and scrub it down with a wire brush if you want.
Heat to 1525F and quench, reheat to 1525 and quench, reheat to 1525F and quench. Then temper twice at 400F. After that, I would soak it in vinegar again for 4-5 hours to remove any remaining scale....then grind and test the edge.

If using my extreme normalization/grain refinement regime, you would heat to 1625, quench 1550, quench, 1350, quench, 1250, cool to black. then heat to 1525F and quench followed by the tempers at 400. Probably more than this blade needs.

The carbon on the surface is burned out in decarb and scale ( iron oxide). The carbon in the steel about five thousandths deeper should be fine. With an edge of .025-.030, you should be able to grind about .010" off each side without any problem. Before re-grinding the bevels, I would grind the edge back .030" to .060". All this should be done after the HT.

Just for info, any area that you leave the decarb surface on will have a very different color in an FC etch from the newly exposed good steel ... so you can dip and check the progress. You could even grind the bevels leaving the decarb on the upper area and get a faux hamon look.
 
Ok guys ... Im going to do a triple quench and work the edge back a bit. I appreciate your help.

Thanks a Bunch?

Bobby
 
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