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本帖最后由 沼泽 于 2013-1-11 22:30 编辑
克虏伯火炮 发表于 2013-1-11 21:39 
当时美国为了抵御硬质被帽的侵彻，在表面硬化装甲方面走上了误区，认为这样大厚度的硬化是有必要的。
基 ...
大厚度的硬化也不能用百分比进行表示，渗碳深度由渗碳工艺和渗碳时间决定的，渗碳不可能达到那么厚，美国渗碳技术用的是哈维装甲用木炭做原料，和德国的克虏伯气体渗碳工艺不同渗碳速度和渗碳深度都比用kC的差。
PS：
其实在navweaps里面就有渗碳装甲的说明
DECREMENTAL HARDENING: This is a special form of quenching/chilling designed to get a deep, gradually-softening face on a face-hardened plate. Grüson Chilled Cast Iron armor formed its face using the chilling process, which was possible because of the very high Carbon content of the cast iron allowing rather rapid hardening. However, armor steels use rather low amounts of Carbon to prevent brittleness, so deep hardening is only possible by the use of alloying elements--primarily Chromium, though Molybdenum was used extensively after World War I in addition to Chromium--that slow down the transformation of austenite to ferrite, allowing martensite to form deeper in the plate where the cooling rate is slower, and that form additional carbides to increase the hardness by more efficiently using the existing Carbon. Nickel was also of use here, since it toughened steel considerably and allowed higher hardnesses to be used while keeping the toughness above the minimum required. This process applied to steel was introduced by Krupp in 1894 as his famous Krupp Cemented face-hardened armor (later called KRUPP CEMENTED "OLD TYPE"--abbreviated "KC a/A" (see below)--in Germany after World War I to separate it from the post-World War I improved KC "NEW TYPE" ("KC n/A" (see below)) developed by Krupp during the late 1920's and early 1930's) and in less than a decade had made all other forms of full-strength armor steel obsolete when used for the primary protection of warships and, later, armored land vehicles--including all previous homogeneous metal armors because his new Chromium-Nickel-Steel was harder and tougher and thus more resistant than the older Nickel-Steel. It was originally combined with the cementing process, but a few face-hardened armors dispensed with cementing and successfully (or not) employed decremental hardening by itself. Except for a final, post-hardening temper (not always used in early KC-type armors) and minor machining, the decremental hardening process was the last heat treatment applied to a KC-type face-hardened Chromium-Nickel-Steel armor plate. The plate was completely heat treated for optimum crystal structure, mechanically worked (hammered, rolled, and forged), cemented (if used), and shaped to as close to its final form as possible, then laid flat and packed around the edges with an insulating layer of sand or loam, so only its face and back surfaces were exposed. Any portions of the face where holes were to be cut were covered with thick insulation (usually asbestos) to reduce both the rates of heating and of cooling and thus prevent hardening when quenched. All temperatures and times used were carefully regulated using data from previous tests and production runs. The plate was run into an oven and raised slowly to an even red hot temperature below the CHT, then the face surface only was evenly blasted by flaming jets to raise it to a much higher white hot temperature and the plate allowed to soak in this condition for a specified time, depending on the plate size and thickness. The CHT would gradually move into the plate in a flat front and when the timer indicated that it had reached the desired depth (which varied considerably between manufacturers and date made over a wide range), the plate would be removed from the oven and either both the face and back would be sprayed with high pressure water cold (original Krupp technique) or the plate would first undergo dipping of the face in water and/or oil (British Vickers KC-type armor manufactured prior to World War I, for example) prior to the final water quench. The result was a "decrementally hardened" or "deep" face layer of circa 500 Brinell (535 Brinell is the hardest I know of, and not in a normal prodcution plate) just behind the cemented layer (if used), dropping off gradually in hardness to the level of the unhardened back in one of several ways, depending on the final face and back temperatures, the heating time, and the plate's metallurgical makeup. The original KC a/A armor had the deep face layer's hardness drop off with increasing depth in either a straight line or a "ski-slope" (a rapid, ramp-like drop in the middle of the face layer, but slow near the surface and near the unhardened back, like a child's slide) to about 350 Brinell at about 20% into the plate from the face surface. At this point the drop in hardness would become much steeper in another ski-slope--the transition layer--until it merged with the back layer's circa 225 Brinell hardness at 33-35% of the plate from the surface of the face, being a constant hardness from there to the back surface of the plate. Except for the sudden drop in hardness at the back of the cemented layer (if used) of from 650-700 Brinell to the circa 500 Brinell level, in no place was there any sudden change in hardness, though there was the relatively sudden change in the rate that the hardness was dropping at the boundary of the deep face layer and the transition layer. The cemented layer/deep face layer combined is also called the undrillable portion of the face, while the entire cemented layer, deep face layer, and transition layer combined is called the chill or, loosely, the face, though this can be confused with the more limited scope deep face layer part of the undrillable portion of the chill. The width of the undrillable chill portion, the width of the transition layer, the hardness level where the transition layer begins, and the average hardness of the back layer were all changed slightly or considerably by later adopters of this process, including, after World War I, by Krupp itself. KC n/A armor increased the back layer hardness to 240 Brinell (the maximum used by anyone); increased the depth of the chill to 41% (very exact value); and adjusted the hardness drop in the undrillable chill layer to exactly match the transition layer drop so that the chill went from about 500 Brinell just behind the cemented layer in a single straight line or gradually-flattening curve, making the point where the transition layer starts invisible (it should be when the hardness drops to somewhere around 350 Brinell, depending on whose definition of "undrillable" you use!). This armor was tempered and was much superior to KC a/A in every way. In other face-hardened plates, the deep face layer hardness stays constant for some depth and then begins to decrease in a ski-slope (deep face layer/transition layer boundary again somewhat arbitrarily specified) or in a very sudden drop (essentially no transition layer at all). U.S. Navy BETHLEHEM THIN CHILL Class "A" armor (see below) was unusual in that it had essentially no deep face layer, with the drop in hardness being so steep behind the cemented layer that the cemented layer itself became the entire face and only a narrow, very steep transition layer not much thicker than the cemented layer connecting the cemented layer with the back layer, while U.S. Navy MIDVALE NON-CEMENTED Class "A" armor (see below) had a extreme chill depth of over 80% of the plate. The depth of the chill (actually the thickness of the unhardened back layer as a percent of the total plate thickness) is important not only for damaging projectiles, but also because the hard chill always fails by breaking (brittle fracture) and this is a surface phenomenon, as opposed to ductile tearing, where the entire volume of armor is distorted and pushed aside by the projectile as it penetrates (see SCALING on page 3). Due to the difficulty of precisely controlling temperature and due to the use of the circa-1"-thick cemented surface layer in most KC-type armors, the minimum plate thickness for the deep face process described above was usually circa 4" (102mm) or greater (6" (15.2cm) for Japanese World War I-era VICKERS CEMENTED armor, for example), though Krupp and Witkowitz originally made their KC armors down to 3.2" (8cm) up through the end of World War I--even they increased the minimum to 4" after World War I.
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发表于 2013-1-11 17:13
发表于 2013-1-11 17:26
有段没来，这帖子内容好颠覆啊...SKC34雄起了,壮哉我大RM更是...
发表于 2013-1-11 22:43