Tuesday, 13 September 2016

Nickel-Free Armour

"Decree of the State Committee of Defense #1586
RE: trials of the new nickel-free armour for T-34 hulls

The State Committee of Defense decrees that:
  1. The People's Commissariat of Ferrous Metals (comrade Tevosyan), People's Commissariat of Tank Production (comrade Malyshev), and GABTU are to be informed that trials of nickel-free armour and cast T-34 turrets from MZ-5 gave satisfactory results, matching the technical requirements for MZ-2 nickel armour.
  2. The People's Commissariat of Tank Production (comrade Malyshev) must:
    1. Begin production of cast turrets and cast armoured components for T-34 tanks from nickel-free MZ-5 steel instead of MZ-2 steel at factories #112, #183, #178, and Uralmash by May 10th of this year
    2. Produce 15 hulls at factory #112 by May 10th of this year from nickel-free MZ-5 steel and perform ballistic trials by May 10th in cooperation with GABTU.
  3. In the event of satisfactory welding and trials results, allow the People's Commissariat of Ferrous Metals, People's Commissariat of Tank Production, and GABTU to begin using MZ-5 nickel-free steel instead of MZ-2 in production of tank hulls, according to technical requirements.
  4. The People's Commissariat of Ferrous Metals (comrade Tevosyan) must provide the necessary amount of low carbon ferrous chrome for production of MZ-5 armoured steel.
Chairman of the State Committee of Defense, I. Stalin"

RGASPI 644-2-50

1 comment:

  1. Nickel in steel alloy is benefitial by allowing a larger degree of toughening. Nickel-free armor is perfectly feasable but requires certain other alloying agents, such as copper (in small amounts), boron (in tiny amounts) or chromium (in small amounts)and -ideally- molybdenium plus a specific heat treatment sequence. Enhanced skills in metallurgy are required to reduce as much as possible exposure to the brittle tempering temperature range (depending on section thickness and alloys present, either a very slow cooling or a very rapid quench). Ni-free armor is highly suspect of temper embrittlement due to the presence of chromium or boron.
    Plus, it´s only feasable within a very narrow range of section thicknesses (50mm being the thickest practicable section thickness without massive loss in ductility or toughness).
    Ni-free, full armor grade homogenious steel was patented by Krupp 1932 and information of this material was passed to the soviets in the years of cooperation between Hitler and Stalin.

    In Germany, these armor steels were classified as thermo-mechanically treated steel (requiring hot rolling, annealing, hot rolling,...) and were mainly applied in thin sections of vehicle and screen armor to provide protection without or with much reduced nickel content for early and mid war PzII-IV.

    Do You happen to have the date of the document and informations in regard to MZ-2 and MZ-5 steel composition?