苏联二战全口径弹的硬度测试

节选自Metallurgical Exmination of Soviet 45mm, 57mm, and 85mm APHE Projectiles; ADA443218; 1952-08-06

The 45MM and 57MM shot were uniformly heat treated to a hardness of approximately Rockwell C 50-55 while the 85MM shot was decrementally hardened from Rockwell C 46-50 at the nose to  Rockwell C 25 at the base. 

45 mm和57 mm均匀热处理，整体硬度50~55 HRC。85 mm硬度自头部的46~50 HRC降低至尾部的25 HRC

The carbon contents of the subject Soviet shot are in the range of 0.32 - 0.38% as compared to 0.50 - 0.60% carbon employed in domestic shot steels. The result of the lower carbon content is to lower the maximum hardness of the shot to the range of Rockwell C 50-55 as compared to Rockwell C 60 for American shot. 

苏联穿甲弹用钢含碳量在0.32~0.38%之间，而国内通常为0.5~0.6%。更高的含碳量意味着更高的硬度，国产穿甲弹的硬度通常约为60 HRC

The bodies of all three shot were made from medium carbon, manganese-silicon-chromium steels of very similar compositions, see Table I. Although the evidence provided by the subject three shot is, of course, extremely limited, there seems to be no indicationof selection of alloy content consistent with hardenability equirements to harden through sections of varying size. As a matter of fact, the largest shot, the 85MM APHE, has the lowest carbon and total alloy content. In domestic practice, it is usual to employ higher alloy steels for shot of larger caliber in order to obtain full hardening of the heavier sections. The low carbon content of the subject shot is noteworthy. In American practice, it is common to employ alloy steels having carbon. contents of 0.50-0.60% in order to harden the shot to Rockwell C 60 upon quenching. Steels with 0. 32-0.38% carbon harden to Rockwell C 52-55 upon complete transformation to martensite.

弹体材料均为中碳锰硅铬钢，成分相近，见下表。没有证据表明苏联会根据尺寸调整合金成分。口径最大的85 mm碳和合金含量最低。国内通常的做法是在增大口径同时提高合金含量以确保大截面能完全硬化。(译注：作为示例，Armox 500和Mars 600均随板厚增大相应地调整成分)

Manganese - silicon- chromium steels containing approximately 1.5% silicon have been widely observed in Soviet ordnance materiel, being used in gun components, armor, and armor-piercing shot. The low molybdenum content indicates that this element is present only as a residual rather than as an alloying element. Molybdenum is very widely employed in this country in ordnance materiel to minimize or avoid temper embrittlement, being used in quantities in the range of 0.20 to 0.60%. Since this element is almost a specific for avoidance of embrittlement, its absence in Soviet ordnance materiel may safely be taken as an indication of its strategic nature in the Soviet metal supply.

硅含量1.5%的锰硅铬钢广泛用于苏联火炮、装甲和穿甲弹。钼含量很低，表明仅是杂质而非合金元素。钼广泛用于国产军用钢，以抑制回火脆化，含量通常在0.2~0.6%。(译注：最典型的RHA 4340/40CrNiMo(A))

The hardness patterns of the subject shot are radically different from those of domestic shot. In American practice, shot are heat treated to the maximum hardness obtainable (Rockwell C 60 and higher) and then differentially tempered to have hardnesses of approximately Rockwell C 59 at the bour relet and gradually dropping to Rockwell C 45 at the base. It has been found that lowering the hardness of shot noses below Rockwell C 60 results in more extensive shatter of the shot against armor, as well as a reduction in the velocity of impact at which hatter initiates.

美国穿甲弹的头部硬度通常高于60 HRC，倒角处降低至59 HRC，尾部45 HRC。头部硬度低于60 HRC会导致弹体受破坏靶板破坏过强。

The reduced hardness of the 45MM and 57MM shot is understandable, since an effort was obviously made to increase the toughness of these shot since the blunt nose shape of these shot make shatter almost inevitable against heavy armor targets and at high terminal velocities. In the case of the 85MM shot, however, the low overall hardness should detract from the penetration performance of this ogival nosed shot.

45 mm和57 mm的低硬度是为了提高韧性，因为钝头弹在高速打击重装甲是几乎必然发生破坏。对于尖头的85 mm，降低硬度应该会劣化穿甲能力。