Spheroidizing in itself is not a bad thing. It is an excellent method of annealing that gives maximum ductility without messing with grain size or sheeting up carbide, much better than lamellar annealing which results in problems in both areas. With todays prevalence of high speed machining many steels are taken to a 95% to even a 98% spheroidal condition. With simple steels like 10XX and W series, this is not so much a problem since cementite very easily dissolves in short order with reasonable temperatures. But with alloy steels the more complex carbides when spheroidized to this level are much more stable and will result in lower than desired hardness unless soak temperatures are increased. The answer to this is indeed a normalizing pretreatment, but this is to correct insufficient austenite solution rather than grain size, which is more or less unaffected by spheroidizing.

I spent most of this spring researching studying and documenting these concepts in detail for a project I released about a month back. But I have also been advising many in our industry about how to cope with the effects on alloy steels for at least four or five years now.

Glad you could comment on this, Kevin. Obviously I don't have the testing equipment you have so I'm limited to a visual check of grain size. I've seen a 1095 blade made by stock removal method not respond to typical grain reducing cycles. How much time at what temperature is necessary to break down the sherodized grain structure?

I'd be interested in seeing your research on the topic. Is it available to the public?

After even just a few forging cycles, your steel is anything but spherodized. The reducing heat steps you give will be necessary to REPAIR what forging caused. Same for the San-mai. (Ask me how I know.)

The high temperature soak to dissolve the spherodized carbon - then followed by the lower heats - would be most necessary to those doing stock removal, as their steel never reaches the temp necessary to equally distribute the C.

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I'd be interested in seeing your research on the topic. Is it available to the public?

You can find the information on my website, but since it is in a format that is for sale I prefer to avoid pitching it, or promoting it here. I find the approach of answering forum questions with "hey buy my..." tacky.

Kevin, have you noticed steel in a highly spherodized state not responding to grain reduction measures? I've seen the problem of steel not hardening properly in W2. Some years ago I had a W2 blade that was tempered at about 450 that held an edge moderately well...200 cuts through 3/8 sisal rope and still cutting hair. The problem was that it Rockwell tested in the low 40's! In your opinion could there be a correlation between not getting the steel hot enough to break down the spherodized state and lack of hardenability? Could it be related to grain refinement as well? In your experience how much time at what temperature is necessary to get rid of spherodizing? What if someone forges at the lower ranges if the forging spectrum?

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Kevin, have you noticed steel in a highly spherodized state not responding to grain reduction measures? I've seen the problem of steel not hardening properly in W2. Some years ago I had a W2 blade that was tempered at about 450 that held an edge moderately well...200 cuts through 3/8 sisal rope and still cutting hair. The problem was that it Rockwell tested in the low 40's! In your opinion could there be a correlation between not getting the steel hot enough to break down the spherodized state and lack of hardenability? Could it be related to grain refinement as well? In your experience how much time at what temperature is necessary to get rid of spherodizing? What if someone forges at the lower ranges if the forging spectrum?

In many heat treatment approaches grain refinement can be in opposition to carbide refinement, due to the temperatures involved (i.e. high temps bust carbides but grow grain, low temps refine grain but grow carbides). I have certainly seen heavy spheroidization effect hardenability in alloyed steels that form more stable carbides, due to lack of free carbon for austenite solution. For this a proper normalization, at that steels recommended temperature, is all that needed. I have seen smiths who ignore proper forging temperatures, that forge too low to obtain full solution during forging, that have added to the spheroidization effects, and end up frustrated until a good normalization is performed. Unfortunately some have went on to blame a perfectly good steel for these results rather than re-examine their methods, leaving them with a little egg on their face when I had absolute beginners pegging the needle on the Rc tester from following proper procedures with the same steel.

And possibly without examination under a microscope we may notunderstand exactly what we see? I just ran two test pieces of 1095 and W2 with the same temps, 1600,1550, 1500, and 1450. After hardening I broke the two samples. The 1095 was fine graines (to the naked eye) while the W2 shows somewhat larger grain size. Could the mix of pearlite and martens it give the appearance of larger grain because of a "dirty" due to lack of hardenability?

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And possibly without examination under a microscope we may notunderstand exactly what we see? I just ran two test pieces of 1095 and W2 with the same temps, 1600,1550, 1500, and 1450. After hardening I broke the two samples. The 1095 was fine graines (to the naked eye) while the W2 shows somewhat larger grain size. Could the mix of pearlite and martens it give the appearance of larger grain because of a "dirty" due to lack of hardenability?

It is often possible to troubleshoot without any fancy test equipment, one just needs to know what to look for, and discern what is observed. There is so much more to steel properties than grain size, but fractured end grain can be right there staring us right in the eye and so we tend to focus on it at the expense of other observations. Your suggestion is a very good one, a mixed microstructure of martensite and pearlite results in two very different fracture modes, the rougher fracture surface giving a coarser appearance regardless of actual grain size. Most bladesmiths aren't aware that observing the end of broken steel is not actually the way ASTM grain size is measured, which is actually a process of cross sectioning, polishing and etching with very specialized reagents to be able to see the grain boundaries at exact magnification with one of several formula methods applied to obtain an ASTM number. To work with fractured end grain (i.e. Shepherd) you need a control comparison but more importantly, as you pointed out, you need through hardening to insure the uniformity of the fracture mode.