Contact Vanitec
Tel: +44 (0)1959 563400
Fax: +44 (0)1959 562563
E-mail: info@vanitec.org
Vanitec Limited,
Winterton House, High Street, Westerham, Kent TN16 1AQ, England
Reg No. 06490949
Vanadium - provides strength in structural steels around the world.
Bridges and Buildings
Vanadium is the most widely used alloying element for strengthening steels
employed in buildings and bridges. It is the most effective alloy for increasing
the strength of reinforcing bars used for buildings, tunnels and bridges;
it is added to bars for prestressed concrete structures and suspension ropes
and it is a commonly adopted alloying element for strengthening steel sections.
Vanadium is used alone and in combination with other alloying elements for
strengthening steel plates for box girder and other types of bridge. It is
added to steels designed to resist fire and earthquake and is employed to
strengthen steels designed to resist the corrosive effects of weather.
Interchange bridge, Johannesburg
The bridge at the Geldenhuis interchange near Johannesburg consisting of two 30 m spans involves four girders welded from vanadium steel plate. The steel has a yield strength of 350 N/mm² and a Charpy V impact minimum of 27J at -30°C required by local codes to guarantee the necessary resistance to fatigue.
Gion bridge, Sweden
The welded bridge across the river Gion in Sweden is built with high strength "as
rolled" steel plates containing vanadium and titanium.
Central Plaza, Hong Kong
Several hundred tonnes of vanadium are present in the reinforcing bars used in the construction of the numerous ferroconcrete buildings in Hong Kong including the Central Plaza - the highest building in Asia.
Sears building, Chicago
The famous Sears building in Chicago, is reputed to be the highest in the
world and is made with high strength vanadium steel sections.
Lee house, London
Lee House straddles London Wall, one of the City of London's main thoroughfares. The tension members of the trusses across the 27 m roadway supporting an 18 storey office block are anchored in cast vanadium steel nodes each weighing up to 18 tonnes. These are the largest steel castings ever used in the building industry.
Cranes and Drag Lines
Vanadium provides the strength and toughness for Cranes and Draglines
Vanadium - reduces weight and increases payload
Vanadium steels are used in many types of crane, parts of drag lines, and
trucks working in open cast mines and in road construction.
In cranes and the spars of drag lines, vanadium provides the strength in rolled and heat treated sections where the maximum strength-to-weight ratio is required.
Vanadium steels are also used in universal beams and in heavy plates (>330mm thick) where strength and rigidity are important.
In addition vanadium steels are used for the buckets of some drag lines enabling heavier loads to be lifted without distortion.
By suitable alloy composition and/or heat treatment, steels can be used in these machines which will resist fracture under impact loading conditions even when they are used in low temperature environments.
High strength steels containing vanadium have been used extensively for the booms of cranes and draglines, reducing the weight of the booms or enabling heavier loads to be lifted. Normalised vanadium-manganese steels are used in the form of plates up to 340 mm thick for various stressed members of drag lines including tension members in the gantry backs, masts and mast links.
Vanadium steels enable larger buckets to be used and increased efficiency to be achieved. By the use of quenched and tempered nickel-chromium-molybdenum-vanadium steels, having a yield strength of 890 /mm², in which vanadium precipitation gives secondary hardening and strengthening, loads up to 10 tonnes can be lifted by telescopic arms when extended to 60 m.
Steels for heavy duty trucks
Vanadium is used in steels required to have strength, abrasion resistance and toughness in many parts of trucks especially those operating in mines and other severe environments.
By the use of vanadium steels, protection can be given to cabs of trucks
where ore, coal or over-burden can fall on the cab.
Vanadium steels also provide reinforcement to the side walls of trucks while they are being loaded. Vanadium steels are used in the frames to enable the maximum strength-to-weight ratio to be achieved so that the maximum pay-load can be carried.
Industrial Plan and Tubular Structures
Vanadium provides the varied combinations of properties in cast iron, heavy steel forgings and plate for Industrial Plant and Tubular Structures.
Vanadium - for reliability and durability in steel and cast iron
Vanadium in rolling Mill rolls
Vanadium is an essential alloying element in a number of steels and cast irons used for rolls in steel mills. The vanadium, however, has several different functions depending on the product being rolled.
Cast iron finishing rolls for steel Plate Mills
Up to 1% vanadium is added to cast iron rolls used for hot rolling of steel
plate. the function of the vanadium is to increase the depth of chill and
hardness on the surface of the rolls so that when polished the high quality
surface of the roll imparts an equally high quality surface to the steel
plate.
The hard surface containing vanadium carbides also ensures that cracks do not form under thermal cycles resulting from the rolling of the hot steel.
Vanadium also refines the graphite of the core thus increasing the strength and toughness of the iron enabling it to resist impact loading during rolling operations.
Forge steel back up rolls in four high Mills
Small amounts of vanadium (of the order of 0.1%) are added to forged steel
back up rolls of four high mills to refine the grain size and hence increase
the toughness of the rolls. This enables the rolls to resist impact loading
during rolling operations.
Similar rolls with up to 0.25% vanadium have been used in the work rolls of hot strip mills.
Heat treated steels for industrial compressor rotors
Fully heat treated nickel-chromium-molybdenum-vanadium steels having a yield
strength of 890 /mm² and a high resistance to wear are used for large
rotors operating at high speeds to circulate large volumes of air in sinter
and pelletising plant in the steel industry.
Vanadium steels in tubular structures
As long ago as the 1970s vanadium was used to provide extra high strength in steels used for welded tubular structures. Such tubes were used in the British Airways hangars at Heathrow airport and in the spectator stand at Bristol City Football stadium.
More
recently vanadium steels have been used to provide strength in thick walled
structural seamless tubes such as those in some of the columns in the terminal
building at Stanstead airport and in certain complex joints in the sports
stadium in Sheffield, England.
In all these applications the use of high strength tubular structures enables large unsupported spans to be built so that in sports stadia spectators can have views unimpeded by pillars and aircraft hangars can be constructed so that large aircraft can have free access.
Vanadium steels have also been used in tubes in chemical plant and oil refineries.
Hot formed pressure vessels
In many parts of chemical plant made from steel plates, such as pressure vessels, the plates have to be formed to shape after heating to make them soft. Vanadium steels which depend for their strength on grain refinement and precipitation formed during normalising are very suitable because the thermal cycles during fabrication involve temperatures similar to those used in normalising. As a result of this the structure and properties of the plates remain largely unchanged despite the fabrication conditions.
Vanadium steels are also preferred for bends and manifolds in high strength pipelines because the heating for the forming operations has little effect on their strength and properties.
Vanadium steels are frequently used for forged valves because they can be normalised after forging to give high strength without distortion.
Vanadium steels in industrial buildings
In North America "as rolled" vanadium steel sections are used extensively in the frames and roofs of industrial buildings. In these steels vanadium carbonitrides precipitated in ferrite provide the strength.
Tools and Dies
Vanadium creates the hardness for cutting edges and wear resistance required in Tools and Dies.
Vanadium tool and die steels are melted in induction furnaces and scrap steel is recycled without significant loss of vanadium.
Vanadium in high carbon steels forms hard primary carbides during casting
sometimes in combination with other alloying elements present in the steel.
These carbides are stable at high temperatures and mostly remain in primary
form throughout subsequent forging and heat treatment operations. They are
the basis of the wear resistance and cutting performance of cold pressing
dies and tools. The stability of these carbides at high temperatures makes
the steels containing them suitable for high speed machining operations and
gives wear resistance to hot forging and pressing dies.
In addition to the primary carbides, some vanadium remains in solution and contributes to the hardenability, strength and toughness of the tools and dies. During heat treatment some additional hardening occurs to give increased wear resistance as a result of the precipitation of very fine particles of secondary vanadium carbides.
By varying the composition and heat treatment a wide variety of property combinations can be obtained. This makes it possible for steels to have the very different properties required in high speed tools and dies used in the automobile and heavy engineering industries and for domestic hand tools such as spanners and screwdrivers
Hot forging dies
Dies for hot forging, stamping and pressing operations have to withstand high surface temperatures (up to 1500°C) and thermal shock. In addition, they have to resist high pressures and, in the case of stamping dies, impact loading. In order to meet these conditions of service microstructures giving a tough steel with a hard surface are required and they are provided by relatively high tungsten-vanadium steels. The tungsten and vanadium provide the hardenability necessary to ensure a tough core and a surface containing carbides which provide the resistance to wear.
Many dies can be resurface after use and are therefore recyclable.
High speed steel
All tools used for the machining of steel at high speed, as in the production
of automobile components, require a cutting edge which is stable at the high
temperature reached at the tool tip which can be in excess of 600°C.
Particles of vanadium carbide formed during the casting of the steel and
which remain out of solution throughout the heat treatment operations satisfy
this requirement. The original high speed steel developed at the beginning
of the century contained 1% vanadium. Improved and lower cost versions were
developed in the middle of the century and they are now the standard steels
and contain 2% vanadium.
Cold pressing dies and tools
Cold pressing dies and tools handling hard materials must have high abrasion resisting surfaces. These can be produced by high vanadium contents. Normal casting tends to give coarse particles of carbides which can lead to cracking during forging except for small tools. Recent developments have taken place in powder metallurgy techniques which have resulted in refined microstructures so that large tools and dies can now be made. Tools and dies containing as much as 10% vanadium can now be produced for punches and dies by these powder metallurgy methods. Knives, shear blades, extrusion dies, pelletiser blades and screw conveyors, handling metals, plastics and other abrasive materials also benefit from powder metallurgy alloying. Similar tools operating in wet conditions are made from corrosion resistant steels containing 4% vanadium.
General tool steels
Vanadium is added to many grades of carbon steel used for lathe tools and milling cutters, blacksmith's tools, stamping dies, rock drills, chisels, wood cutting tools and razor blades. The precipitation of fine particles of vanadium carbide during heat treatment of the tolls increases their hardness and improves their cutting efficiency giving them longer life. Vanadium, through its effect on hardenability increases the depth of hardness in heat treated tools which increases their resistance to crushing, their toughness and hence their resistance to fracture under loading.
Chrome-vanadium steels for spanners and domestic tools
In spanners, screwdrivers and other domestic and engineering tools vanadium
and chromium are added to increase the surface hardness and resistance to
distortion under load. Vanadium is added with chromium to provide strong,
wear resistant tools.
Tap dies, reamers, punches, planes, chisels and shear blades
In tools which have a cutting function the cutting edge is provided by hard carbides. The iron carbide of carbon steels is supplemented by the harder carbides of vanadium and tungsten in tools which undertake severe cutting operations. Thus planes, chisels, reamers and shears, especially those used for cutting hard materials or heavy sections of softer materials, are made from vanadium-tungsten steels.
Cutlery steels
Vanadium is added to chromium cutlery steels to increase the hardness of the steel and to give a longer-lasting, better cutting edge.