Střední tanky 2. světové války

Sheldon Cooper: "It's consistent with my personality."

As early as spring 1941 the arsenals were directed to reduce their use of tungsten in tools and dies wherever possible, but the savings in this area were necessarily limited. It was in production of armor-piercing small arms bullet cores, and in certain types of artillery ammunition, that the greatest savings were made. At the beginning of the defense period an electric-furnace steel known as WD 74100, containing up to 4 percent tungsten, was used for all armor-piercing small arms cores, although Frankford Arsenal and Watertown Arsenal had experimented with many other types of steel during the 1920's and 1930's and had found some to be nearly as good as the tungsten steel. As the volume of small arms production rose steadily in 1940 and early 1941 and tungsten became extremely scarce, Ordnance switched from tungsten steel to manganese-molybdenum steel for armor-piercing cores. This effected an estimated saving of over 7,500 tons of tungsten in 1942-43 production. When electric-furnace steel-making capacity became critical, Ordnance engineers discovered they could make satisfactory cores for both .30-caliber and .50-caliber ammunition from open-hearth manganese-molybdenum steel. Later, acceptable .30-caliber cores were made from high-grade carbon steel without the addition of any alloys at all. (s. 483)

[In artillery ammunition, one of the earliest and largest savings resulted from the elimination of nickel in 75-mm. and 3-inch armor-piercing-capped shot. Before the war, shell manufacturers had used steel containing a high percentage of nickel, averaging 3.5 percent, but, as tests showed that nickel was not needed to produce shot with the required ballistic properties, the use of nickel steel in shot bodies was discontinued in April and May 1942. According to estimates, during the next eighteen months this one change saved nearly 4,000 tons of nickel.] A similar change was made in the smaller 37-mm. armor-piercing-capped shot bodies; a steel containing up to 4 percent tungsten was replaced by a chrome-molybdenum steel when tungsten became very scarce. (s. 486)

By then a 90-mm. HVAP round had been developed which, following combat tests, was standardized as the M304 in June. Containing an 8-pound core of tungsten carbide as opposed to the 4-pound core of the 76-mm. HVAP shot, [...]

In essence, APCR projectiles consist of a hard, high-density, sub-calibre core within a light alloy body. In consequence, most of the kinetic energy imparted to an APCR projectile is concentrated in the sub-calibre core and hence on a smaller area of the target. This, together with the high hardness of the core, leads to greater armour penetration than that achieved with full calibre AP projectiles fired from the same gun. The sub-calibre cores or penetrators have been generally made of tungsten carbide sintered using cobalt as the bonding agent or binder, and have had densities ranging from about 14 300 to 16 300 kg/m3, compared with 7850 kg/m3 for steel. Tungsten carbide is relatively brittle and as a result penetrators made of it break up as they pierce armour, creating a highly lethal spray of particles. However, the relative brittleness of tungsten carbide penetrators also causes them to fracture when they strike armour obliquely, so that their armour piercing performance falls off appreciably as the slope of the target armour increases.

At first, the penetrators of APDS projectiles were similar to those of APCR projectiles. In particular, they were also made of tungsten carbide and as a result their armour penetration was reduced considerably by well sloped armour. Tungsten carbide was still used for the penetrators of the early 105mm APDS projectiles such as the L22 but in the L28 version, which was developed in Britain in the mid-1950s and its US M392 counterpart, a tungsten alloy cap was added to the penetrator. The tungsten alloy was less hard but more ductile than tungsten carbide and the addition of caps reduced the tendency of the penetrators to shatter, improving their armour penetration at other than normal impact. In the early 1960s the performance of APDS projectiles was improved still further with the development in Britain of the L52 projectile, which had a penetrator as well as a cap of tungsten alloy.