Ducol or "D"-steel is the name of a number of high-strength low-alloy steels of varying composition, first developed from the early 1920s by the Scottish firm of David Colville & Sons, Motherwell.
Applications have included warship hull construction and light armouring, road bridges, and pressure vessels including locomotive steam boilers and nuclear reactors.
The original Ducol, or "D"-steel, is a manganese-silicon steel, a toughened version of the new, proven standard construction steels developed by David Colville & Sons just after WW1. [lower-alpha 1]
It was an improvement on British Admiralty "HT" (High Tensile) steel, a shipbuilding and light armour steel developed c1900 and used through the end of WWI. HT was a carbon steel with a small amount of nickel, which allowed it to be hardened to a greater level without cracking (i.e. increased "toughness"). Foreign similar steels – for example, German "Low-%" Nickel Steel and U.S. High Tensile Steel (HTS) – were more complex alloys using chromium, vanadium and molybdenum. [3] [ better source needed ]
Up until about 1945, Ducol generally contained only manganese and silicon as alloying elements. More recent weldable grades (Ducol W21, W25, W30, and W30 grades A & B) include varying amounts of nickel, chromium, copper, molybdenum and vanadium.
Grade | % C | % Mn | % Si | % P | % S | % Ni | % Cr | % Mo | % Cu | % V | Notes |
---|---|---|---|---|---|---|---|---|---|---|---|
Royal Navy "HT" steel | 0.35~0.40 | 0.8~1.2 | 0.15 | [4] | |||||||
§R. Sumida bridges | 0.24~0.30 | 1.4~1.6 | [5] | ||||||||
IJN Ducol | 0.25~0.30 | 1.20~1.60 | ? | ||||||||
Ducol, RN "D"-steel | 0.24~0.30 | 1.50 | 0.06~0.10 | trace | trace | [5] | |||||
§Chelsea Bridge | 0.25 | 1.52 | 0.13 | 0.03 | 0.03 | 0.36 | [7] | ||||
Ducol W21 | 0.23 | 1.7 | 0.5 max | 0.25 max | [8] | ||||||
Ducol W25 | 0.2 max | 1.5 max | 0.5 max | 0.3 max | 0.3 max | [8] | |||||
Ducol W30 | 0.18 max | 1.4 max | 0.5 max | 0.8 max | 0.25 max | 0.5 max | 0.1 max | [8] | |||
Ducol W30 Grade A | 0.11~0.17 | 1.0~1.5 | 0.4 max | 0.7 max | 0.4~0.7 | 0.2~0.28 | 0.3 max | 0.04~0.12 | [8] | ||
Ducol W30 Grade B | 0.09~0.15 | 0.9~1.5 | 0.4 max | 0.7~1.0 | 0.4~0.7 | 0.2~0.28 | 0.3 max | 0.04~0.12 | [8] | ||
§Sizewell 'A' | 0.1 | 1.4 | ? | 0.2 | 0.5 | 0.25 | 0.1 | [9] |
Although modern grades of Ducol are termed 'weldable', this doesn't necessarily mean 'easily weldable'. A 1970 report on an explosion in a cylinder made of Ducol 30 found that in Ducol W30, embrittlement of the heat-affected zone (HAZ) occurs in welds unless post-weld heat treatment takes place at a sufficient temperature (675C). [10]
In addition, the original product from the 1920s was also weldable (ie 'capable of being welded'), but with dubious results. The Imperial Japanese Navy built large warships using all-welded Ducol structural elements, which swiftly led to severe problems with the Mogami-class cruisers.[ citation needed ]
Ducol has been used for bulkheads in both general construction and against torpedoes, and for light armour in warships of several countries, including the British, Japanese and perhaps Italian navies. [11] After WW2 the highest grades of the commercial shipbuilding steels were based on this type of steel. [12]
Ducol steel was used in HMS Nelson and HMS Rodney (1927) to save weight. [13]
It was used in British anti-torpedo-system design practice in its last battleships. The internal hull and torpedo bulkheads and internal decks were made of Ducol or "D"-class steel, an extra-strong form of HTS. Much of the load-bearing portions of King George V-class battleships including the weather deck and the bulkheads were made from Ducol [14]
HMS Ark Royal's fully-enclosed armoured hangar and the armoured flight deck which it supported were constructed of Ducol.[ citation needed ]
Other types of armour used on Navy ships:
The Imperial Japanese Navy (IJN) made considerable use of Ducol made under licence by Japan Steel Works in Muroran, Hokkaidō, Japan: the company was set up with investment from Vickers, Armstrong Whitworth and Mitsui. [15]
The Mogami-class cruisers were originally designed with all-welded Ducol bulkheads which were then welded to the ship's hull. The resultant faults caused by electric welding used in the structural portions of the hull resulted in deformation, and the main gun turrets were unable to train properly. They were re-built with riveted construction, and the other two were redesigned. [16] [17] [18]
All of the following ships or classes (the list is not complete) used Ducol in structural bulkheads and protective plating:
In addition, the IJN's '25-ton' type river motor gun boat had an all-welded hull, protected by 4-5mm Ducol steel.
The Italian Navy used a similar type of steel to Ducol in its Pugliese torpedo defense system. This underwater "bulge" system was introduced in the Italian Littorio-class battleships, and in the completely rebuilt versions of the Italian battleship Duilio and the Conte di Cavour-class battleships. The inboard-facing side consisted of a layer of silicon-manganese high-tensile steel from 28-40mm thick called "Elevata Resistenza" (ER) steel, which was probably somewhat similar to the British Ducol ("D" or "Dl") Steel used for light armour and torpedo bulkheads in WWII. [26]
During WWII many Soviet tanks used Ducol type steel due to a lack of chromium and nickel. [12]
The Eitai-bashi (1926) and Kiyosu-bashi (1928) bridges over the Sumida River in Tokyo seem to have been some of the first bridges to be made with Ducol, at the time a state-of-the-art technology.
The bridges were built by Kawasaki Dockyard Co., to replace earlier crossings which were destroyed in the 1923 Great Kanto earthquake. High-tensile Ducol was used for the lower supports of the Eitai-bashi tied-arch bridge, and for the upper cables of the Kiyosu-bashi self-anchored suspension bridge. The steel was made at Kawasaki's Hyogo Works, Kobe. [27]
Ducol was also used in the construction of the stiffening girders of Chelsea Bridge (1934-1937) joined by HTS rivets. A small amount of copper was added to the mix to improve corrosion resistance. [7]
Used in the construction of the Glen Quoich Road Bridge, Aberdeenshire - built 1955 by Sir William Arrol & Co. crossing the Qoich Water between Mar Lodge and Allanaquoich, not far from where it joins the River Dee. [28] [29] [30]
Ducol has been used in pressure vessels including steam boilers and solid wall ammonia converter shells as used in the Haber–Bosch process. Normalised and tempered Ducol W30 has been used in heavy walled nuclear reactors. [31]
In the UK, the British Standard for low alloy steels used for high temperature pressure purposes is BS EN 10028-2:2006. It replaced the old BS1501 Part 2: 1988. [32]
The boiler plates for the Southern Railway 4-6-0 Lord Nelson class locomotives, designed by Richard Maunsell in 1926 to work at 250 psi (1,700 kPa), were made of Ducol. [33]
A number of pressure vessels & boilers constructed with Ducol (or similar materials) have failed. Such failures have all been because of faulty fabrication or testing of the vessel, rather than the steel itself. [34]
Ducol was used in the boiler shells at Sizewell ‘A’ nuclear reactor. [35] [36]
Failure of Sizewell ‘A’ boiler under hydrostatic test, May 1963. "The boiler was 18.9 m long, 6.9 m diameter, and was fabricated from plates 57 mm thick in a low alloy steel, conforming to BW87A specification (similar to Ducol W30, but with lower C), of composition 0.1C, 1.4Mn, 0.5Cr, 0.25Mo, 0.2Ni, 0.1 V. The cause of the failure was attributed to a shock impact loading, when the wooden chocks on which the vessel was resting during the hydro-test suddenly gave way." [37] [38]
Ducol would have been used for the later stations, but was superseded by prestressed concrete pressure vessels (PCPV). [39] The advantage of prestressed concrete is that once the initial compression has been applied, the resulting material has the characteristics of high-strength concrete when subject to any subsequent compression forces, and of ductile high-strength steel when subject to tension forces. [40]
In December 1965 a boiler made of Ducol was under construction by John Thompson, Wolverhampton, for ICI's ammonia plant at Fisons' Immingham works. It was being pressure-tested after heat treatment when it exploded, throwing one chunk weighing 2 tons right through the workshop wall and landing 50 metres away. [41] [42]
In Ducol W30, embrittlement of the heat-affected zone (HAZ) in welds occurs unless post-weld heat treatment takes place at a sufficient temperature (675C). [10] The amount of pre-heating and the type of welding consumables (eg low hydrogen) can affect hydrogen embrittlement (or cracking) in the weld. [43]
A boiler drum made with Ducol plates, manufactured by Babcock & Wilcox Ltd (now Altrad Babcock) at Renfrew, near Glasgow, to BS 1113 (1958) was installed at Cockenzie Power Station in East Lothian, Scotland. It exploded on 6 May 1967 under repeated pressure testing. According to Jim Thomson, the failure was caused by a crack (created during the original manufacturing process) which occurred next to an economiser nozzle replaced during testing; the crack had penetrated part-way through the thick wall of the pressure vessel. [44]
Hiei (比叡) was a warship of the Imperial Japanese Navy during World War I and World War II. Designed by British naval architect George Thurston, she was the second launched of four Kongō-class battlecruisers, among the most heavily armed ships in any navy when built. Laid down in 1911 at the Yokosuka Naval Arsenal, Hiei was formally commissioned in 1914. She patrolled off the Chinese coast on several occasions during World War I, and helped with rescue efforts following the 1923 Great Kantō earthquake.
The Mogami class (最上型) was a ship class of four cruisers built for the Imperial Japanese Navy (IJN) during the 1930s. They were initially classified as light cruisers under the weight and armament restrictions of the London Naval Treaty. After Japan abrogated that agreement, all four ships were rearmed with larger guns and reclassified as heavy cruisers. All participated in World War II and were sunk.
The Yamato-class battleships were two battleships of the Imperial Japanese Navy, Yamato and Musashi, laid down leading up to World War II and completed as designed. A third hull, laid down in 1940, was converted to an aircraft carrier, Shinano, during construction.
Ōyodo (大淀) was a light cruiser built for the Imperial Japanese Navy (IJN) during World War II, and was the only ship of her class completed before the end of the war. Designed to command submarine operations, she was obsolete upon completion in 1943. The ship was used as a transport and to escort the navy's capital ships for the rest of the year. Ōyodo was lightly damaged by American aircraft in early January 1944 during one transport mission and returned home several months later to begin conversion to serve as the flagship of the Combined Fleet.
Yahagi (矢矧) was an Agano-class cruiser which served with the Imperial Japanese Navy (IJN) during World War II.
The four Agano-class cruisers were light cruisers operated by the Imperial Japanese Navy. All were named after Japanese rivers. Larger than previous Japanese light cruisers, the Agano-class vessels were fast, but with little protection, and were under-gunned for their size. They participated in numerous actions throughout World War II.
Itsukushima (厳島) was the lead ship in the Matsushima class of protected cruisers of the Imperial Japanese Navy. Like her sister ships, the name Itsukushima comes from one of the traditional Three Views of Japan, in this case, the Itsukushima Shrine in Hiroshima prefecture on the Seto Inland Sea, home to a famous Shinto-Buddhist shrine dedicated to the Buddhist goddess Benzaiten.
Aki (安芸) was one of two Satsuma-class semi-dreadnought battleship built for the Imperial Japanese Navy (IJN) during the first decade of the 20th century. She was the second battleship built domestically in Japan and the first to use steam turbines for propulsion. The ship was named for Aki Province, now a part of Hiroshima Prefecture. The ship saw no combat during World War I. Aki was disarmed in 1922 and sunk as a target in 1924 in accordance with the terms of the Washington Naval Treaty of 1922.
Settsu (摂津) was the second and last of the Kawachi-class dreadnought battleships built for the Imperial Japanese Navy (IJN) in the first decade of the 20th century. Following the Japanese ship-naming conventions, Settsu was named after Settsu Province, now a part of Osaka prefecture. During World War I she bombarded German fortifications at Qingdao during the siege of Qingdao in 1914, but saw no other combat. She was placed in reserve in 1919 and was disarmed in 1922 in accordance with the terms of the Washington Naval Treaty.
Algérie was the last treaty cruiser constructed for the French Navy. Designed and built in response to the Italian's Zara class of 8-inch gun cruisers, she was a totally new design and not based on the previous ships. The armoured caisson system used in Foch and Dupleix was abandoned in favour of a full armoured belt enclosing both the magazines and machinery spaces. She abandoned the unit propulsion system used previously and grouped her boilers forward leading to the reduction to a single funnel. She was one of the first vessels to utilize super heating boilers. Welding was used primarily in place of the normal rivetting in previous vessels. She maintained the same main armament but her secondary guns were increased to 100 mm guns. She served in the Mediterranean Sea after entering service then searched for German surface raiders at the beginning of the war. She was at Toulon, France, at the time of the Armistice and remained there until scuttled in November 1942.
Krupp armour was a type of steel naval armour used in the construction of capital ships starting shortly before the end of the nineteenth century. It was developed by Germany's Krupp Arms Works in 1893 and quickly replaced Harvey armour as the primary method of protecting naval ships, before itself being supplanted by the improved Krupp cemented armour.
The Tosa-class battleships were two dreadnoughts ordered as part of the "Eight-Eight" fleet for the Imperial Japanese Navy (IJN) during the early 1920s. The ships were larger versions of the preceding Nagato class, and carried an additional 41-centimeter (16.1 in) twin-gun turret. The design for the class served as a basis for the Amagi-class battlecruisers.
The Shōkaku class consisted of two aircraft carriers built for the Imperial Japanese Navy (IJN) in the late 1930s. Completed shortly before the start of the Pacific War in 1941, the Shōkaku and Zuikaku were called "arguably the best aircraft carriers in the world" when built. With the exception of the Battle of Midway, they participated in every major naval action of the Pacific War, including the attack on Pearl Harbor, the Indian Ocean Raid, the Battle of the Coral Sea, the Guadalcanal Campaign, the Battle of the Philippine Sea and the Battle of Leyte Gulf.
The Hatsuharu-class destroyers were a class of Imperial Japanese Navy destroyers in the service before and during World War II. The final two vessels in the class, completed after modifications to the design, are sometimes considered a separate "Ariake class".
The Fuji class was a two-ship class of pre-dreadnought battleships built for the Imperial Japanese Navy (IJN) in the mid-1890s. They were the first battleships in the IJN, and were constructed in the UK as Japan lacked the industrial facilities needed to build them. Their design was based on the battleships being built for the Royal Navy at that time.
The Tsukuba-class cruisers were a pair of large armored cruisers built for the Imperial Japanese Navy (IJN) in the first decade of the 20th century. Construction began during the Russo-Japanese War of 1904–05 and their design was influenced by the IJN's experiences during the war. The British development of the battlecruiser the year after Tsukuba was completed made her and her sister ship Ikoma obsolete, as they were slower and more weakly armed than the British, and later German, ships. Despite this, they were reclassified in 1912 as battlecruisers by the IJN.
Tosa (土佐) was a planned battleship of the Imperial Japanese Navy. Designed by Yuzuru Hiraga, she was envisioned as the lead ship of the Tosa class of two 39,900-long-ton (40,540 t) ships. The battleships would have been armed with ten 410 mm (16.1 in) guns and brought Japan closer to its goal of an "Eight-four" fleet. All work on the ship was halted after the Washington Naval Conference and the signing of the Washington Naval Treaty. As the vessel had to be destroyed in accordance with the terms of the treaty, the incomplete Tosa was then subjected to tests to gauge the effect of Japanese weaponry before being scuttled on 9 February 1925.
The Ibuki class, also called the Kurama class, was a ship class of two large armoured cruisers built for the Imperial Japanese Navy after the Russo-Japanese War of 1904–1905. These ships reflected Japanese experiences during that war as they were designed to fight side-by-side with battleships and were given an armament equal to, or superior to existing Japanese battleships. The development of the battlecruiser the year before Ibuki was completed made her and her sister ship Kurama obsolete before they were completed because the foreign battlecruisers were much more heavily armed and faster.
The Ibuki-class cruisers were the last class of heavy cruisers built for the Imperial Japanese Navy (IJN). In order to save design time, the ships were essentially repeats of the earlier Mogami class. Begun during World War II, only the lead ship, Ibuki, was launched, but she was in the process of being converted into a light aircraft carrier when construction was suspended in 1945. She was scrapped the following year. The unnamed second ship was scrapped less than a month after being laid down in order to clear her slipway for an aircraft carrier.
Naval armor refers to the various protections schemes employed by warships. The first ironclad warship was created in 1859, and the pace of armour advancement accelerated quickly thereafter. The emergence of battleships around the turn of the 20th century saw ships become increasingly large and well armoured. Vast quantities of heavily armoured ships were used during the World Wars, and were crucial in the outcome. The emergence of guided missiles in the last part of the 20th century has greatly reduced the utility of armor, and most modern warships are now only lightly armored.