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Harvey armor
Harvey armor
Harvey armor
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8 inches (200 mm) Harveyized nickel-steel plate from 1894

Harvey armor was a type of steel naval armor developed in the early 1890s in which the front surfaces of the plates were case hardened. The method for doing this was known as the Harvey process, and was invented by the American engineer Hayward Augustus Harvey.

This type of armor was used in the construction of capital ships until superseded by Krupp armor in the late 1890s.

The Harvey United Steel Company was a steel cartel whose chairman was Albert Vickers [la]. The year 1894 would see the ten main producers of armor plate, including Vickers, Armstrong, Krupp, Schneider, Carnegie, and Bethlehem Steel, form the Harvey Syndicate.

Predecessors

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Before the appearance of compound armor in the 1880s, armor plating was made from uniform homogeneous iron or steel plates backed by several inches of teak to absorb the shock of projectile impact. Compound armor appeared in the mid-1880s and was made from two different types of metal, a very hard but brittle high-carbon steel front plate backed by a more elastic low-carbon wrought iron plate. The front plate was intended to break up an incoming shell, while the rear plate would catch any splinters and hold the armor together if the brittle front plate shattered.

Compound armor was made by pouring molten steel between a red-hot wrought iron backing plate and a hardened steel front plate to weld them together. This process produced a sharp transition between the properties of the two plates in a very small distance. As consequence, the two plates could separate when struck by a shell, and the rear plate was often not elastic enough to stop the splinters. With the discovery of nickel-steel alloys in 1889, compound armor was rendered obsolete.

Production process

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Harvey armor used a single plate of steel, but re-introduced the benefits of compound armor. The front surface was converted to high carbon steel by "cementing". In this process, the steel plate would be covered with charcoal and heated to approximately 1200 degrees Celsius for two to three weeks. The process increased the carbon content at the face to around 1 percent; the carbon content decreasing gradually from this level with distance into the plate, reaching the original proportion (approximately 0.1–0.2 percent) at a depth of around an inch. After cementing, the plate was chilled first in an oil bath, then in a water bath, before being annealed to toughen the back of the plate. The water bath was later replaced with jets of water to prevent the formation of a layer of steam which would insulate the steel from the cooling effect of the water. The process was further improved by low temperature forging of the plate before the final heat treatment.

While the American navy used nickel steel for Harvey armor (roughly 0.2 percent carbon, 0.6 percent manganese, 3.5 percent nickel), the British used normal steels since their tests had shown that ordinary steel subjected to the Harvey process had the same resistance to penetration as nickel steel, although it was not quite as tough.

Harvey armor was taken up by all of the major navies, since 13 in (330 mm) of Harvey armor offered the same protection as 15.5 in (390 mm) of nickel-steel armor. It was in turn rendered obsolete by the development of Krupp armor in the late 1890s.

See also

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References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Harvey armor

View on Grokipedia
from Grokipedia
Harvey armor is a type of face-hardened naval steel armor developed in the late , characterized by a super-hard, high-carbon surface layer—typically 1 inch deep—fused to a tougher, more ductile backing, designed to resist projectile penetration by combining on the exterior with elasticity in the body. Invented by American engineer Henry A. Harvey of , the process involved steel plates in bone charcoal at temperatures exceeding 2,000°F for two to three weeks, raising the face carbon content to 1-1.1% while the overall plate retained about 0.20% carbon, followed by a controlled quench and oil cooling to achieve a Brinell of 600-700 on the surface. The development of Harvey armor marked a significant advancement in protection, emerging in 1890 as an improvement over earlier nickel-steel and compound armors, with the first successful application on a 10.5-inch Creusot plate treated at the . Initially tested under the guidance of U.S. officers like W.M. Folger, it demonstrated superior ballistic resistance, such as a 3-inch Harvey armor plate stopping a 4-inch shell at 1,700 feet per second, leading to contracts for plates up to 14 inches thick by 1893. Often produced as Harveyized nickel-steel with 3.25-3.50% nickel and 0.60% manganese for enhanced toughness, it provided 15-20% greater resistance than plain nickel-steel equivalents, making it a standard for Indiana-class battleships such as the USS Indiana and Massachusetts in the 1890s. This armor's key advantage lay in its ability to distribute impact energy across the plate's thickness, preventing localized deformation and cracking while outperforming homogeneous steel by forcing projectiles to fragment against the hardened face. However, by the mid-1890s, it was gradually superseded by cemented armor, which offered deeper hardening and better performance against capped projectiles, though Harvey armor remained influential in naval metallurgy until the early .

History and Development

Invention and Early Experiments

Hayward Augustus Harvey (1824–1893) was an American engineer and inventor based in , known for his innovative work in and processes. Throughout his career, Harvey held numerous patents related to machinery and treatment, but his most significant contribution emerged in the field of naval armor during the late . Motivated by the vulnerabilities of existing armors such as compound armor, which consisted of layered and but suffered from under impact, Harvey sought to develop a more reliable single-piece plate with a hardened face for enhanced ballistic protection. Harvey's experiments began in earnest around 1891, focusing on a cementation process to infuse carbon into the surface of steel plates, creating a hard outer layer while maintaining a ductile interior. He conducted initial quenching trials to refine the hardening technique, heating the plates in contact with carbon-rich materials like bone charcoal and then rapidly cooling them to achieve the desired gradient hardness. These early efforts culminated in demonstrations to the U.S. Navy in 1891, including a notable test at the Annapolis naval ordnance proving ground where a treated steel plate withstood repeated impacts from six-pounder projectiles without breaking, highlighting its potential for cruiser armor. Further trials followed at Indian Head in December 1892, where a curved 10.5-inch Harveyized plate from Bethlehem Iron Works exhibited remarkable endurance against gunfire, marking the first such test on a curved surface. The breakthrough came in 1893 with a pivotal proof at the U.S. Naval Proving Ground in , where a 13-inch Harveyized plate—intended for battleship side armor like that of the —successfully resisted attacks from heavy projectiles. This test demonstrated superior performance compared to compound armor, with the Harvey process enabling equivalent protection at reduced thickness (approximately 15-20% lighter than untreated nickel-steel equivalents), thus proving its viability for naval applications without the risks of layered designs.

Formation of the Harvey Syndicate

Following the successful demonstration of the Harvey process through proofs in 1893, major international steel producers established the Harvey Syndicate in 1894 to commercialize and license the technology globally. The syndicate, also known as the Harvey United Steel Company, was formed by key firms including in the , in , Carnegie Steel in the United States, and in the United States, creating a to manage production and distribution. This organization, capitalized at £630,000 and chaired by Albert Vickers, aimed to standardize the Harvey armor manufacturing process across participating entities while preventing unauthorized replication. The syndicate's licensing agreements granted exclusive rights to its members for producing Harvey-treated armor plates, enforced through a royalty system that required payments per ton of output. , for instance, the U.S. negotiated contracts with Carnegie and that included royalties of 0.5 cents per pound (capped at $75,000 annually) paid to the Harvey Steel Company, ensuring controlled access to the patented process. These arrangements not only protected but also coordinated international output, with the syndicate allocating orders and stabilizing prices to avoid competition. A pivotal catalyst for the syndicate's international adoption was the U.S. Navy's trials of Harvey armor in 1894 at the Indian Head Proving Ground, where plates for the battleship Indiana withstood severe impacts, validating the process's reliability. This success prompted rapid licensing expansions to European navies, as the syndicate leveraged the results to secure agreements with additional producers like Schneider in France and Armstrong in the UK. By standardizing production techniques, the group facilitated uniform quality and scalability, enabling widespread naval applications. Economically, the syndicate generated substantial royalties for the Harvey interests following inventor Hayward A. Harvey's death in 1893, with U.S. firms alone deriving over 50% of their profits from armor contracts in the late . The monopoly maintained control over global production into the early 1900s, until patent expirations around 1911-1913 led to its liquidation and the technology's broader dissemination.

Predecessors

Compound Armor

Compound armor represented a significant advancement in naval protection during the mid-1880s, consisting of a multi-layer design that featured a hard steel face plate, typically 4 to 6 inches thick, welded or fused to a thicker backing of softer wrought iron or mild steel to provide both hardness against penetration and elasticity to absorb impacts. This construction addressed the limitations of earlier all-wrought-iron armor, which lacked sufficient resistance to armor-piercing shells, by combining the brittleness-resistant properties of iron with the superior hardness of steel. Invented by Alexander Wilson of the British firm Charles Cammell & Co., the process involved casting molten steel onto a preheated wrought-iron plate in a rotating mold to ensure bonding, with successful trials conducted by the British Admiralty as early as 1888. Both the British and French navies adopted armor in the mid-1880s as an interim solution to enhance defenses amid rapid advancements in . In Britain, it was applied to vessels like HMS Inflexible, where 9-inch compound plates protected the turrets, offering effective resistance equivalent to about 12 inches of against heavy ordnance. The French integrated it into ships such as the Amiral Baudin, launched in 1883, and Formidable in 1885, marking early large-scale use of the material to counter emerging threats from high-explosive shells. Overall, a 10-inch plate provided approximately 25% greater ballistic resistance than a comparable plate, demonstrating its value in providing layered protection without the full weight of solid steel. Despite these benefits, compound armor suffered from critical drawbacks that limited its long-term viability, including a pronounced tendency for where the steel face could separate from the iron backing under severe impact, compromising structural integrity. Production was also more costly due to the complex assembly and fusion processes required, often involving specialized firms like Cammell, which increased expenses compared to simpler homogeneous plates. Furthermore, it proved vulnerable to high-velocity projectiles, such as 6-inch steel shots exceeding 1,900 feet per second, which could penetrate even thicker sections in some tests, as seen in early evaluations where layers failed to hold against modern armor-piercing rounds. These issues on HMS Inflexible highlighted occasional test failures, where the armor's multi-layer design did not consistently withstand prolonged engagements. This paved the way for transitions to single-piece nickel-steel homogeneous armor as a more reliable alternative.

Nickel-Steel Homogeneous Armor

Nickel-steel homogeneous armor emerged in as a significant advancement in naval plating, introduced by the French firm Schneider & Co. as a single-piece designed to replace multi-layered compound armor. This material incorporated 3 to 4 percent into a low-carbon base, typically with around 0.20 percent carbon, to produce tougher and more uniform plates without the risks of earlier designs. The key properties of nickel-steel armor stemmed from its homogeneous composition, which provided uniform throughout the plate rather than relying on layered construction. The addition of enhanced and tensile strength compared to plain , allowing the material to absorb impacts better while maintaining a Brinell of approximately 200-250 across its thickness. With a carbon content of 0.2-0.3 percent, it offered improved over or high-carbon steels, though it remained susceptible to deformation without surface treatments. Following successful U.S. Navy trials in the early 1890s, the Navy adopted nickel-steel homogeneous armor for its new battleships, marking a shift toward all-steel protection. It was prominently used in the armored cruisers and , with plates up to 12 inches thick providing the primary , outperforming compound armor in penetration resistance during early tests against 6- to 10-inch projectiles. These ships, constructed between 1888 and 1895, benefited from the material's single-piece integrity, which reduced manufacturing complexities. In the U.S., firms like and Carnegie produced nickel-steel plates, facilitating adoption by the Navy. Note that later ships in the Indiana class, including USS Oregon, incorporated Harvey face-hardening on nickel-steel plates. Nickel-steel armor provided slightly greater resistance than compound armor of the same thickness, requiring less material for equivalent protection and reducing weight compared to compound designs. Additionally, its uniform structure made it prone to cracking and brittle failure under oblique impacts, where shock waves could propagate through the entire plate without a hardened face to dissipate energy. Harvey's later face-hardening process built directly on this single-piece nickel-steel foundation to address such vulnerabilities.

Production Process

Material Composition

Harvey armor plates were forged from ingots of low-carbon alloys optimized for the , which introduced a carbon-rich layer on the surface while preserving a ductile core. In the United States, the primary variant employed a - base composition of approximately 0.2% carbon, 0.6% , and 3.5% by weight, enhancing toughness and resistance to cracking under impact. British production, in contrast, favored plain with 0.2–0.3% carbon, avoiding to leverage more straightforward manufacturing while achieving comparable baseline properties. Following cementation and , the carbon content formed a profile, reaching about 1% at the face for superior and tapering to 0.1–0.2% carbon at a depth of roughly 1 inch, ensuring a tough, fibrous interior that absorbed energy without shattering. levels varied between 0.5% and 1% across producers to balance and , with trace impurities controlled to minimize . These plates were typically produced in thicknesses of 10 to 16 inches for main belt armor on battleships, forged from large ingots to achieve uniform microstructure prior to treatment. The quenching step locked in this carbon profile, creating the signature face-hardened structure.

Cementation and Quenching

The Harvey armor production process began with cementation, a carburizing step where steel plates were tightly packed in bone charcoal or similar carbonaceous materials within an airtight oven to infuse carbon primarily into the face surface. This packing, often using a mixture of animal and wood charcoal with a thin layer of pure animal charcoal directly against the plate, was covered on the sides and back with sand or loam to limit carbon penetration to the desired depth. The packed plates were then heated to temperatures around 1200°C, approximating the melting point of cast iron, and maintained at this level for approximately 2-3 weeks, allowing carbon to diffuse into the steel face to create a hardened layer. Following cementation, the quenching sequence was critical to achieving the desired face-hardened structure while minimizing defects. Plates were exposed to high-pressure water jets or sprays, a refinement introduced in the mid-1890s, which rapidly hardened the carburized face by transforming it into while leaving the interior relatively tough and ductile. This was followed by lowering the plates into an for controlled cooling to prevent cracking due to . The process was applied to single-piece nickel-steel plates, a key innovation over predecessors that relied on multiple layers, enabling greater homogeneity and scalability. By the mid-1890s, refinements allowed treatment of thicker plates up to 14 inches, including techniques like reforging after cementation to improve thickness control and surface integrity. After quenching, the plates underwent annealing at lower temperatures around 600°C for 1-2 weeks to relieve internal stresses, break up large crystals in the cemented layer, and enhance overall without compromising the hard face. This post-quenching , often conducted in air from a cherry-red , ensured the plate's structural for naval applications.

Properties and Performance

Hardness Profile

Harvey armor exhibits a pronounced gradient, with the face achieving a Brinell hardness of 600-700, imparting glass-like to shatter incoming projectiles upon impact. This hardness decreases gradually through the plate's thickness to a core value of approximately 190 Brinell in nickel-steel variants, ensuring sufficient to absorb residual without . The process following cementation is responsible for establishing this decrementally hardened profile, transitioning from a brittle exterior to a tougher interior. In typical plates, the hardened layer penetrates 1 to 2 inches deep, though this depth increases proportionally in thicker armor—for instance, reaching 2-3 inches in 12-inch plates—to maintain effective resistance across varying dimensions. The overall tensile strength of Harvey nickel-steel armor measures around 95,000 psi, balancing the face's projectile-shattering capability with the back's energy absorption. Testing standards employed Brinell hardness measurements to evaluate the armor, revealing a 15-20% improvement in face resistance compared to homogeneous nickel-steel plates of equivalent thickness.

Ballistic Resistance and Equivalents

Harvey armor demonstrated superior ballistic resistance in U.S. Navy trials from 1894 to 1897, where a 12-inch plate suffered incomplete penetration of 7 inches from 6-inch armor-piercing shells at velocities around 2,100 ft/s, with the plate breaking apart but held by bolts, highlighting its ability to limit despite damage. These tests highlighted the armor's ability to shatter or deform projectiles upon impact, preventing deep penetration even against high-velocity strikes. In comparative evaluations, 13 inches of Harvey armor provided ballistic protection equivalent to approximately 15.5 inches of nickel-steel armor, translating to 1.2 to 1.5 times the protective efficiency per inch of thickness relative to predecessors such as compound armor and nickel-steel. This enhanced efficiency stemmed from the face-hardened design, which distributed impact forces more effectively across the plate. Against oblique impacts at 30-degree angles, Harvey armor excelled due to its hard outer layer deflecting and fragmenting shells, reducing compared to normal incidence, though performance diminished at perpendicular hits where shattering was less pronounced. The hardness profile briefly referenced here enabled consistent shattering, contributing to this oblique resilience. Standardized ballistic assessments underscored its transformative impact on naval protection levels.

Applications

Adoption by Major Navies

The was the first major naval power to adopt Harvey armor following successful trials in the early . Initial contracts were awarded to the and in February and March 1893 for approximately 6,500 tons of nickel-steel armor treated via the Harvey process, at an additional cost of $50.40 to $100.80 per ton depending on plate thickness, plus royalties to the Harvey Steel . By 1895, the U.S. Navy mandated Harvey armor for all new constructions, securing further production through to meet procurement needs for emerging designs. The Royal Navy followed suit in 1895, licensing the process through as part of the newly formed Harvey United Steel Company syndicate, which facilitated controlled global distribution among major producers. This adoption enabled the integration of Harvey armor into the Majestic-class battleships, marking a shift to comprehensive protection schemes in British while favoring a plain variant for certain applications. Other navies rapidly incorporated Harvey armor by 1896–1897, driven by syndicate licensing that provided access to the technology. Germany's Kaiserliche Marine procured it through in 1896, adapting the process for domestic production ahead of further innovations. France integrated Harvey armor into and designs by 1897, as seen in vessels like Guichen. and similarly adopted it around the same period, with 's applying it to the Fuji-class battleships laid down in 1896. By 1900, Harvey armor had become the predominant choice for vertical protection in new constructions worldwide, shaping the standard for pre-dreadnought era designs across multiple powers.

Use on Specific Warships

The pioneered the use of Harvey armor on major warships during the 1890s. The USS Oregon (BB-3), commissioned in 1896, was equipped with an 18-inch thick Harvey armor belt that provided comprehensive protection along the amidships. The USS Iowa (BB-4), commissioned in 1897, featured 12- to 14-inch Harvey armor plates mounted on a nickel-steel backing for the main belt, enhancing both hardness and overall structural integrity. The Royal Navy rapidly integrated Harvey armor into its pre-dreadnought fleet following its development. HMS Majestic, the of her class commissioned in 1895, incorporated 9-inch Harvey armor for both the main belt and protective deck, representing an early large-scale application of the material. Other navies also adopted Harvey armor for key vessels in the late . On these warships, Harvey armor configurations typically featured main belts ranging from 9 to 18 inches thick to shield machinery and magazines, with turret faces protected by 10- to 12-inch plates for mount resilience. Overall, armor accounted for approximately 40% of a typical pre-dreadnought's displacement, underscoring its dominant role in ship design priorities.

Limitations and Successors

Technical Drawbacks

One significant technical drawback of Harvey armor was its , particularly in the hardened face layer, which could crack under repeated impacts or strikes from high-caliber shells exceeding 12 inches. This arose from the high carbon content (up to 1.05%) in the face, resulting in limited and a tendency for the material to rather than deform elastically, as demonstrated in tests where a 6-inch plate shattered into fragments upon impact from a 4-inch armor-piercing shell at 1,890 ft/s. Such cracking often led to spalling, where fragments of the armor's inner layers were driven inward as secondary projectiles, exacerbating damage behind the plate; ballistic tests in extreme conditions, including high-obliquity hits, revealed extensive face scaling over areas up to 15.5 inches in on 6-inch plates struck by 6-inch projectiles. Production of Harvey armor presented challenges, especially for thicker plates over 15 inches, where inconsistent carbon diffusion during the resulted in variable quality and uneven hardening. The cementation required packing plates in bone charcoal and heating to 2,230–2,500°F for extended periods—up to 6–8 days for a 9.5-inch plate—risking furnace failures, metal fusion, or segregation that could cause internal ruptures and superficial cracks during or tempering. These issues were compounded by the shallow of carbon (typically limited to about 1 inch), making uniform treatment difficult in thicker sections and increasing overall manufacturing time and costs to 2–3 weeks per plate. Thickness limitations further constrained Harvey armor's effectiveness, with a maximum practical depth of around 16 inches beyond which the core remained excessively soft, compromising the plate's overall structural integrity and ballistic performance. In thicker plates, the disproportionate soft backing relative to the thin hardened face reduced elastic dishing and heightened vulnerability to penetration, as the carbonized layer constituted a smaller portion of the total thickness. This core softness also amplified cracking propagation to the edges under impact, limiting reliable use for heavy vertical plating above this threshold.

Replacement by Krupp Armor

Krupp armor, developed by the German Arms Works between 1893 and 1897, represented a significant advancement in face-hardened plating over the Harvey process. It achieved deeper carbon penetration to approximately 30-40% of the plate thickness through a double-heat treatment: an initial stage for grain refinement followed by decremental hardening, where the plate face was embedded in clay, superheated, and selectively quenched with water sprays using gaseous hydrocarbons for cementation. This method, incorporating alloying with , produced a more uniform and resilient hardened layer compared to Harvey armor's shallower cementation. Krupp armor demonstrated 15-20% superior protection per inch of thickness against projectiles, with reduced brittleness that prevented face-layer cracking on initial impacts, allowing better performance against subsequent hits. For instance, 11.9 inches of provided equivalent resistance to 13 inches of Harvey armor, enabling thinner plates for comparable defensive capability while maintaining structural integrity. This efficiency stemmed partly from addressing Harvey armor's inconsistent hardening, which could lead to variable performance in thicker plates. The transition gained momentum in the late 1890s, with the U.S. Navy adopting armor starting in 1899 for the Wisconsin-class battleships and fully implementing the process by 1900 for subsequent vessels. The Royal Navy followed in 1901, incorporating it into the Formidable-class pre-dreadnoughts, marking a shift from Harvey designs. By , as the revolution unfolded, armor had supplanted Harvey armor entirely in new constructions across major navies. Krupp's widespread dominance was facilitated by licensing agreements from the German firm, enabling licensed production in countries like the (as Carnegie-Krupp Cemented) and the , which accelerated global adoption. Meanwhile, Harvey armor lingered on pre-1900 ships through , but its obsolescence was complete in frontline applications by the era.

References

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