Very few people carried out the heat treatments described in the articles but the Armories were supposedly the leader in metallurgy at the time. The problem was as I have read it is that none of them would listen to the steel makers at the time. The steel companies were doing a better job at the time of WW1 than the armories.
The use of "bone char" was quite common was quite common until the beginning of the WW2. The use of charcoal was also used for many years in some early attempts to carburize steel or maintain an atmosphere. The only problem was it was essentially uncontrollable except as mentioned in the article by the experienced eye. Charcoal was combined with all sorts of stuff in efforts to control the process.
As an atmosphere generator charcoal was replace by spent pitch coke in the early 20's and carried on for many years.
Another popular atmosphere generator was cast iron shavings with the part being wrapped in paper to keep the shavings from sticking to the part.
My original boss who had worked for the military for many years as a metallurgist prior to and during WW2 had several pieces of wrecked 03 Springfields and had pictures showing that the problem was both burning and untempered martensite and everything in between. He said that one biggest problems was that the armories had went from one's and two's to many per batch and had arbitreley extended time at temperature with what would be called today a catastrophic consequence.
As I was reading the article, the statement regarding decalescence didn't sit well. So I decided to do some research on this, and I offer the following;
Decalescence; "a phenomenon, associated with the transformation of alpha iron to gamma iron on heating (superheating) of iron or steel, revealed by the darkening of the metal surface owing to the sudden decrease in temperature caused by the fast absorption of the latent heat of transformation" .
Experienced Japanese sword makers were reported to have seen the decalescence point and added more heat until the shadows were eliminated and the blade was ready for quenching.
Recalescence - "a phenomenon, associated with the transformation of gamma iron back to alpha iron on cooling (supercooling) of iron or steel, revealed by the brightening (re-glowing) of the metal surface owing to the sudden increase in temperature caused by the liberation of the latent heat of transformation".
Note; above definitions from ASM, Glossary of Metallurgical Engineering Terms.
Dawes,
That is an interesting report and most of it makes sense but there are several inaccurate explanations. The most glaring one is, "...the result is crystallization of the interior of the metal structure, creating a great weakness." To say that a metal has crystallized simply means that it has solidified from the melting temperature since all metals have crystals or grains. A metal or alloy can be recrystallized by heating above a certain temperature which is below the melting temperature and then cooled. This temperature is called the recrystallization temperature and lies somewhere between .35 and .5 Tm(absolute melting temperature). What the author is most likely saying when he says "crystallized" is that the metal was overheated causing grain growth and/or insipient melting which can create a "great weakness."
One other statement that does not make sense is that Martensite does not transform from pearlite. Martensite transforms from Austenite and Pearlite transforms from Austenite. This could be very confusing to anyone attempting to learn basic metallurgy.
It seems there was at least one other invalid statement but I don't mean to nitpick. Maybe someone else will comment if it is relevant.
I think metman is confusing the term "crystallized" as it applies to the real world and the term "crystallized" as it applied to the state of knowledge in 1917. A brittle fracture, when examined with the naked eye, looks shiny, with sparkling reflections from the various tiny facets on the surface (be they cleavage facets or intergranular facets). The material was said to be crystallized because it looked like it was made from tiny crystals (shine a bright light on a pile of table sugar or salt some time). "Burning" the steel sounds like a description of using too high an austenitizing temperature, with increased prior-austenite grain size and associated lower toughness and (if memory serves me correctly) a higher ductile/brittle transition temperature. Changing to a two step heat treatment, with a 1300 F second thermal cycle would be tempering any martensite formed during the quench from 1500, and restoring much of the toughness.
SMF1964,
The article had to be written at least some time later than 1927 form context and from the caption or title I assumed July 2004.
In any event, unfortunate but true that the phrase crystallized and broke has carried over from more ignorant times to the present so that folks ought to be apprised of how meaningless that statement is.
