I read somewhere that the double heat treated carbon steel receivers were stronger than the nickel ones. Can anyone confirm/deny this?
Nah. People read Hatcher's Notebook and get caught up in the rah-rah. General Hatcher was the quintessential company man. He must have been an incredible individual to rise to the top of Army Ordnance and lead the Department through WW2. That organization, like all organizations, is full of ambitious, amoral, machiavellian, individuals. He made it to the top, Hatcher must have been one heck of charismatic individual who knew how to get things done, inspire people, and build a group around him who protected him from the back stabbers. You can tell, he was a work a holic, all the while while he was doing his Army job, he is writing books and submitting articles. These public submissions kept him in the public eye.
He wrote Hatcher's Notebook after the war, after he retired, and was working his way to the top of the NRA. And he made that too. A couple years salary as Head of the Executive Board was probably as much, if not more, than his entire compensation in the Army. Hasn't Wayne La Pierre gotten $250,000 of suits, above his $985,000 a year salary? Its a job well worth keeping. At the time, perhaps the most important thing Hatcher could do, was keep on the positive side of his buddies still in the Army. From the time of its creation, up to 1968, the NRA actually thought of itself, and acted as a DoD agency. And I remember, from a 1963 American Rifleman, the amount of resources the NRA was receiving from DoD was equal to a third or a fourth of their budget. So, Hatcher wants to climb to the top of the NRA, and to do so, he must be greener than Army green.
So what you read in Hatcher's Notebook is an account of how the Army sees itself. Forward leaning, perfect, all knowing, the most incredible, best organization that ever existed and ever will exist. The bigger the organization, the more grandiose and self centered they are, and all they want to hear is how wonderful they are. Hatcher writes nothing that can be remotely construed as a criticism of the Army. He knows, ff he says anything negative, the Army will treat him as a pariah. So, in Hatcher's Notebook, the theme of the double heat treat receiver affair is of another fantastic Army triumph over adversity. Springfield Armory found the enemy, and they were those rascally forge shop workers!
Readers inevitably get caught up in the rah-rah. Almost everyone who reads the section on double heat treat receivers ends up believing that the plain carbon steels used in the things were the most advanced materials ever made, and the receivers were the strongest ever made, the most perfect creations that humanity has ever made, and ever will be made. Right? There is a cult of the double heat treat, and strangely, a cult of the single heat treat receivers.
The plain carbon steels used in the double heat treat receivers were the latest and greatest in 1890. Some can argue that WD1325 steel (Class C) was manganese steel, but at the time, they were called plain carbon steels. But even by 1915, steel technology had advanced so much, that the class C steels were, so to speak , long in the tooth. The nickle steel receivers were 3.5% nickle, and in every respect, except cost, superior to the plain carbon steels used in the single heat treat and double heat treat receivers. The class C steels were .2-.3 carbon, this table shows a comparison of 2340 with a .4 carbon.
What is not shown is the number of cycles to failure, alloy steels have superior fatigue lifetime, more energy required to shear at low temperature, and most importantly, heat treat uniformly through the material thickness. Those double heat treat receivers required two heat treat stages, that is doubling the process time. Rock Island had gone over to nickle steel in 1917 or 1918, and Springfield Armory finally went over to nickle steel once their WW1 stocks of class C materials ended. And, they went back to a single heat treatment, if you notice.
It is likely without General Hatcher and his book, we would be pretty ignorant about anything to do with the single heat receivers as the Army did a great job of covering up what happened.
Double heat treat receivers have blown up, and many are brittle. I believe this is due to the fact that the huge stocks of WW1 materials acquired by SA were used throughout the production of double heat treat receivers. Steels made in that period are highly variable, reflecting the period wartime pressures and the lack of sophisticated process controls. It took till about 1927 for the SA WW1 steel stockpile to run out.
The nickle steels used by RIA and SA had 3.5 lbs of nickle per 100 pound billet, and by the time you get to 1940, that was way too much nickle. Alloy steels of that period were using about a half pound of nickle per 100 pound billet. Nickle was then, and now, an expensive, strategic material and it comes from abroad. Conserving natural resources was very important in WW2, anything that had to go by ship, sailed on an ocean filled with U Boats, Japanese I Boats, and sharks!
From Wiki:
Nickle
World production
More than 2.3 million tonnes (t) of nickel per year are mined worldwide, with Indonesia (560,000 t), The Philippines (340,000 t), Russia (210,000 t), New Caledonia (210,000 t), Australia (170,000 t) and Canada (160,000 t) being the largest producers as of 2019.[26] The largest deposits of nickel in non-Russian Europe are located in Finland and Greece. Identified land-based resources averaging 1% nickel or greater contain at least 130 million tonnes of nickel. Approximately 60% is in laterites and 40% is in sulfide deposits. In addition, extensive deep-sea resources of nickel are in manganese crusts and nodules covering large areas of the ocean floor, particularly in the Pacific Ocean.[53]