Uneven hardening/etching damascus

[J.Loose]

I've been having a problem with 1020/1095 damascus of late- I seem to be getting an uneven hardening which results in an uneven etch.

The affected areas tend to be concentrated in the thicker portions of a blade, and the final etch is much deeper there. These areas are occuring in only one material- i.e. the deeper etch is presumably in the 1095 and not the 1020.

At first I was hardening in a motor oil, so I switched to a #50 queching oil from Heatbath. I still had the uneven etches sometimes, although less severe. I then determined that I was quenching too high after more careful testing with a magnet. Still sometimes getting the unevenness I moved to a water quench (not brine; not heated) Again, I still sometimes get this result.

I should mention that the materials are 1020/1095, 100-400 layers. I immediately triple temper in an oven at 400 degrees for one hour each time after quenching. The unevenness is not due to surface grease prior to etching. The earliest, worst examples resulted in a hardening along the thin blade section of a single edged blade with the deeper etch (presumably unhardened) along the thicker spine.

It seems to me that the hardening is the problem- but I cannot eliminate a cause. Sometimes I get this exact result and sometimes the blades come out fine.

Any suggestions?

J.Loose

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[Arthur Washburn]

There may be several causes for your uneven etching. It does sound like hardening may be the trouble, especially if the areas you suspect as not hard are a grey color. This usually indicates the steel is soft. You dont say what state the steel is in when put into the oven ie coated with Turco, in stainless foil or just placed in the oven in its rough shape. If you use Turco you may be appling it to thick. If you use foil, cease using it. Foil is for stainless not carbon. The stainless acts as an insulator and will prevent the steel from losing heat fast enough to obtain optimum hardness. if neither of these previous are true than the problem may lay with how fast you are quenching. 1095 has a low Manganese content of .30/.50 This means it isnt as deep hardening as say 1084 at .60/.90 you may want to switch to 1084 or 1075 which are a bit more forgiving in the heat treat than 1095. Another possible problem may be the low carbon content of the 1020. you may want to try a 1084/L6 or 1084/15-N-20 mix. The change of mix will give you the advantace of a higher carbon content. You should have had satisfactory results heat treating in the motor oil. Water can cause to much stress in simple carbon steel and can result in cracks in your blades if you are not carful.

If you decide the hardness isnt the trouble then these can also cause trouble.

1st what state are you etching in? normally you need to remove .002 minimum from all surfaces to be etched. This removes any carberization that occurs during heat treat and gives you good fresh material to start the etch with.

2nd are you cleaning the steel with any harsh chemicals? Soap and water is the best. If you are using harsh chmicals like acetone, m.e.k., laquor thinner ect this can cause uneven etch.

3rd what are you etching with and what is the dilution. We recommend Ferric Cloride at 5 parts water and 1 part fc. You can get Ferric Cloride at Radio Shack ask for PCB etchant solution. There are other options to etch but I havent used them.

Good Luck

Arthur D. Washburn
ADW Custom Knives
www.adwcustomknives.com
Production Manager for Devin Thomas Damascus

 

[J.Loose]

Thanks for your reply, Beowulf.

What I'm after here is a fairly traditional Norse pattern welded damascus, by which your name implies you might be into...

<font face="Verdana, Arial" size="2">Originally posted by BeowulftheGeat:
There may be several causes for your uneven etching. It does sound like hardening may be the trouble, especially if the areas you suspect as not hard are a grey color. This usually indicates the steel is soft.</font>

Yes, the areas that typically do this come out of the etch a greyer color than the unaffected areas.

<font face="Verdana, Arial" size="2">You dont say what state the steel is in when put into the oven</font>

(Assuming you mean the heat for quenching)

I am heat-treating in a propane forge of the upright Don Fogg pursuasion. I am taking care to heat slowly and evenly. Blades of 5-6" have no problem fitting into the forge and evenly heating. I am heating with a neutral/reducing environment, and checking for critical with a magnet. Sometimes a blade heats past critical and I let it cool, but not down past critical, before quenching. I have wondered if this was a prob.

<font face="Verdana, Arial" size="2">Not using foil or coatings of any kind- trying to keep things fairly low-tech.</font>

(carbon contents)

I am attracted to the notion of using a simple high and low carbon steel. 1020/1095 is described as a "traditional," or "standard," mix, so I decided to pick this one and really get it down before I moved on... although the suggestion of moving down to a 1020/1084 sounds likeable. What about a 1035/1095? Any experience here?

<font face="Verdana, Arial" size="2">1st what state are you etching in?</font>

Thought the prob might be decarb, but on severe cases it would appear evenly on both sides of a blade and sanding further down would not alleviate in any way. I etch with ferric chloride after removing scale-starting with 220 grit belt to 320 and 400 before a tripoli buffed finish. Then I clean with...

<font face="Verdana, Arial" size="2">2nd are you cleaning the steel with any harsh chemicals?</font>

Have tried everything from soap & water to denatured alcohol to acetone- no discernable difference.

<font face="Verdana, Arial" size="2">3rd what are you etching with and what is the dilution.</font>

Using ferric chloride at 1:1 water. Will try more dilution, but don't think that could be the prob.

Production manager? Would you consider contracting out further advice via phone or e-mail? Willing to pay for good info here.

Sincerely,

-J.Loose


Good Luck

Arthur D. Washburn
ADW Custom Knives
www.adwcustomknives.com
Production Manager for Devin Thomas Damascus
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