Thread: RSO # 1

I like it here . I am not getting confused and actually getting what I need out of it. Mike's posted a chart (and 2 tons of other valuable knowledge) and Bruno and everybody is chipping in. I have had all sorts of info come out of this.

This has been a long project for me. I am certainly not in any hurry. I have a long range plan and when this is done that one starts. What I pick up along the way in information is just as good as the tools I select to reach those goals.

I am slow on the Thanking but I start thinking and forget my manners sometimes.

Originally Posted by JDM61

My experience in getting from my Paragon oven to the patented turkey fryer quench tank full of Parks #50 or MacMaster-Carr medium-fast oil is that same as yours. The only hardening "issues' that I have had are incidents of the old "accidental hamon" with thicker W2 blades, but that is not an issue of hand or quenchant speed.

That sounds like a very good set of tools. The accidental hamon is probably due to the lower harden ability of the W2. The section thickness is the limiting factor. There is enough heat retained above the line to prevent hardening and too little below to prevent it. Playing with the cross section a little you can almost specify where the hamon will occur. Fascinating stuff W2.

Yeah, I love that stuff. Some guys have figured out how to get the accidental hamons on purpose and they look wild even at "user grade" hand rubbed finishes like 600 grit. You typically see that done on the big bowies where you know you have enough mass/cross section up by the spine like you said and I have seen some guys use temperatures as low as like 1425 to do that!!! I haven't really figured that out so I have always used that darn messy clay.

Originally Posted by Mike Blue

That sounds like a very good set of tools. The accidental hamon is probably due to the lower harden ability of the W2. The section thickness is the limiting factor. There is enough heat retained above the line to prevent hardening and too little below to prevent it. Playing with the cross section a little you can almost specify where the hamon will occur. Fascinating stuff W2.

Originally Posted by 10Pups

I like it here . I am not getting confused and actually getting what I need out of it. Mike's posted a chart (and 2 tons of other valuable knowledge) and Bruno and everybody is chipping in. I have had all sorts of info come out of this.

Glad you feel this way 10Pups. This is a great thread!

Originally Posted by JDM61

Mike, in looking at the graph, it appears the start of the curve is at around 1300F for O1 austenized at 1490F. The Curie point for iron is 1043K or around 1417F. I have been told that can move up or down a tiny bit depending on alloying, but does the chart reflect something else that I have heard which is that while the conversion to austenite as the heat rises is at the Curie point and above, hence checking to see when the steel becomes non-magnetic, but, for hardening purposes, the undesirable conversion back into stuff like pearlite (assuming no partial martenstic or bainitic formation from air cooling like in stuff like Crucible Champaloy) starts at that lower point as the temperature falls?

I have been wondering about this for a while and I think I have a better understanding now about what would be happening below the Austenitizing temperature but still above recalescence. In a hypereutectoid steel the amount of carbon that can be held in solution in austenite varies with temperature. This is defined as the 'A sub cm' line on a phase diagram. Below this line the carbon would be coming out of solution and forming cementite in the austenite. If the steel was then quenched cementite would remain in the martensite. For 1095 steel the 'A sub cm' lies above the curie temperature and it appears that alloys put the 'A sub cm' line above curie for lower amounts of carbon. I don't know how quickly the carbon comes out of solution below 'A sub cm' but it seems prudent to "start our clock" as soon as we go below the austenitizing temperature

As best as I can tell, that has kind of been the thinking with using the lower austenizing temps for 52100 in particular in that you only put so much carbon into solution and avoid things like excessive RA and perhaps other things like large primary carbides.

Originally Posted by bluesman7

I have been wondering about this for a while and I think I have a better understanding now about what would be happening below the Austenitizing temperature but still above recalescence. In a hypereutectoid steel the amount of carbon that can be held in solution in austenite varies with temperature. This is defined as the 'A sub cm' line on a phase diagram. Below this line the carbon would be coming out of solution and forming cementite in the austenite. If the steel was then quenched cementite would remain in the martensite. For 1095 steel the 'A sub cm' lies above the curie temperature and it appears that alloys put the 'A sub cm' line above curie for lower amounts of carbon. I don't know how quickly the carbon comes out of solution below 'A sub cm' but it seems prudent to "start our clock" as soon as we go below the austenitizing temperature

Originally Posted by JDM61

As best as I can tell, that has kind of been the thinking with using the lower austenizing temps for 52100 in particular in that you only put so much carbon into solution and avoid things like excessive RA and perhaps other things like large primary carbides.

Yes, but does cementite benefit a razor in any way. It would make it more wear resistant and harder to hone.

The harder to hone part is a very interesting aspect with razors from what I have seen in my limited time on here. While not exactly counterintuitive coming from the knife world, It seem to me that razor honing is what might be described as a rather delicate operation where ease of honing can be more important that with other cutting tools. The benefit of the lower temp with 52100 appears to be, by all accounts, even FINER grain structure, fine edge holding ability and more toughness, both of which would seem to be beneficial with the kind of super fine cross sections you see in razors. it is also supposed to be relatively easy to sharpen and lacks some of the ultimate chromium carbide induced wear resistance of the same steel austenized at the "industry standard" temperatures for ball bearings and such. I recall that German metallurgist and knife maker Roman Landes once said that while most of the razors that we see are still made from simple stainless steel like AEB-L and its analogue 13C26 that were specifically formulated for things like razors and surgical instruments, perhaps as many as 70% of the razor blades sold in the world are still made with carbon steel and most of them use 52100 type steel. Guys like Verhoeven, Landes, Cashen and others seem to have determined that 52100 is an outstanding "simple "steel. perhaps one of the best, for fine cutting tasks even after you cut through some of the mythology associated with the steel in the knife making world. By all accounts, the legendary status of a guy like Bob Kramer, at least in the knife making community is, in part. because he managed to NAIL the HT of 52100 for kitchen knives and arguably put it in the same lofty category as perhaps even the Hitachi "paper" carbon steels.
Back on the topic of O1, one advantage you have with it is that is is such a well developed, formulated and proven product that if you can reasonably follow the HT recipe, you are going to get a product that lies somewhere on the quality spectrum between "pretty darned good' and "out freaking standing" for applications like razors and other fine cutting instruments. A lot of what we may talk about here is seeking that "last 2% of performance" hairsplitting (pun intended) but the fact remains that even stuff done by hobbyist craftsmen willing to take the time to learn their hobby is going to be better than most of the stuff the the average consumer, even a well healed one, has every laid hands on.

Originally Posted by bluesman7

Yes, but does cementite benefit a razor in any way. It would make it more wear resistant and harder to hone.

Originally Posted by JDM61

....You typically see that done on the big bowies where you know you have enough mass/cross section up by the spine like you said and I have seen some guys use temperatures as low as like 1425 to do that!!! I haven't really figured that out so I have always used that darn messy clay.

Spend some time watching Japanese smiths work sword blades. They seem to work down in carbon content and temperatures we consider too low and they routinely work in steels that require water to quench in charcoal fires.

I've seen fellows like Daryl Meier weld way below normal welding temperatures. I'm getting to the point where I believe anything can happen despite what the books say.

If any of us metal pounders should be called a "national treasure" Mr. Meier should certainly be on the short list of candidates for that title. I have also heard Kevin Cashen say that he welds his O1/L6 damascus at temperatures lower than "recommended." As for the Japanese smiths, I have heard some cynical types say that they succeed in SPITE of their methods. But you can't argue with the results. LOL

Originally Posted by Mike Blue

Spend some time watching Japanese smiths work sword blades. They seem to work down in carbon content and temperatures we consider too low and they routinely work in steels that require water to quench in charcoal fires.

I've seen fellows like Daryl Meier weld way below normal welding temperatures. I'm getting to the point where I believe anything can happen despite what the books say.