From inside the book Metallurgical fundamentals of the CONTINUOUS CASTING. The presentday position of continuous casting of steel. This monograph provides university professionals and students, those working in the steel industry and steel plant suppliers in related activities. Front Cover. Iron and Steel Institute, - Continuous casting - pages. 0 Reviews. From inside the book QR code for Continuous Casting of Steel.
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CRC Press Published September 1, Reference - Pages ISBN - CAT# K Select Format: Hardback. Quantity: USD$ Continuous Casting of Steel by W. R. Irving, , available at Book Depository with free delivery worldwide. Book Reviews. Continuous Casting of Steel by W.R. Irving. This book is written to provide a detailed account of the development of continuous casting.
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Toggle navigation Additional Book Information. Share this Title. Recommend to Librarian. Shopping Cart Summary. Items Subtotal. View Cart. In the tundish, any inclusions that are less dense than the liquid metal — gas bubbles, other slag or oxides, or undissolved alloys — may also float to the surface and be trapped in the slag layer.
While the tundish and mold fill for the first time at the start of a casting run, the liquid is badly contaminated with oxygen and the first items produced are typically quarantined or diverted to customers who do not require top-quality material. Breakouts[ edit ] A major problem that may occur in continuous casting is breakout of the liquid metal: for whatever reason, the solid shell of the strand breaks and allows the still-molten metal contained within to spill out and foul the machine.
A breakout is usually due to the shell wall being too thin to support the liquid column above it, a condition which has several root causes often related to heat management. If the metal withdrawal rate is too fast, the shell may not have time to solidify to the required thickness even with enhanced cooling sprays.
Similarly, the incoming liquid metal may be too hot and the final solidification may occur further down the strand at a later point than expected; if this point is below the straightening rolls, the shell may break from stresses applied during straightening.
A breakout can also occur as a result of physical irregularities or damage to the shell occurring within the mould during the initial seconds of solidification. Excessive turbulence within the mold may cause an irregular shell pattern that grows abnormally or it may entrap slag droplets within the shell which reduces the wall strength.
If the incoming metal is severely overheated, it may be preferable to stop the caster than to risk a breakout.
Additionally, lead contamination of the metal caused by counterweights or lead-acid batteries in the initial steel charge can form a thin film between the mould wall and the steel, inhibiting heat removal and shell growth and increasing the risk of breakouts. Other considerations[ edit ] Another problem that may occur is a carbon boil — oxygen dissolved in the steel reacts with also-present carbon to generate bubbles of carbon monoxide.
As the term boil suggests, this reaction is extremely fast and violent, generating large amounts of hot gas, and is especially dangerous if it occurs in the confined spaces of a casting machine.
Oxygen can be removed by "killing" it through the addition of silicon or aluminium to the steel, which reacts to form silicon oxide silica or aluminium oxide alumina. However, too much alumina in the steel will clog the casting nozzles and cause the steel to 'choke off'.
Computational fluid dynamics and other fluid flow techniques are being used extensively in the design of new continuous casting operations, especially in the tundish, to ensure that inclusions and turbulence are removed from the hot metal, yet ensure that all the metal reaches the mould before it cools too much.
Slight adjustments to the flow conditions within the tundish or the mould can mean the difference between high and low rejection rates of the product. Starter bar[ edit ] The starter bar, also called a dummy bar, has a free end portion which is flexible for storage and a substantially rigid portion at the end which plugs the mold.
The starter bar is constructed in discrete blocks secured to one side of a planar spine provided in segments and arranged end to end. Adjustable spacers in the form of tapered blocks are disposed between the blocks of the bar to allow the starter bar to be self-supporting in a curved configuration corresponding to the casting path. A more flexible spine in the end portion of the starter bar allows the starter bar to be curved to a tighter radius than that of the casting path while the blocks fan out in an unsupported configuration.
A storage ramp is provided to support the flexible end in the stored position. Before a cast is started, the starter bars are fed through the caster in reverse direction of casting using hydraulic actuators. Once fed all the way to the bottom of the mold, the process of packing the mold can continue to ensure a smooth start up.
Direct strip casting[ edit ] Direct strip casting is a continuous casting process for producing metallic sheet directly from the molten state that minimizes the need for substantial secondary processing. For low-carbon sheet steels, this is a relatively new process which has only achieved commercial industrialization within the last decade. Twin-belt continuous casting employs a moving mold consisting of parallel carbon-steel belts held in tension as top and bottom casting surfaces.
Chains of rectangular steel or copper blocks moving with the belts and spaced according to the desired cast width form the sides of the mold.
Molten metal is introduced into the twin-belt continuous casting machine from a tundish through a nozzle placed between the casting belts.
The metal is cooled by direct contact with the belts which are in turn cooled by high pressure recirculating water.
Various coatings can be applied to the belt casting surfaces to provide required mold interface characteristics and prevent adhesion. The cast metal from the twin-belt continuous casting machine is synchronized with, and directly fed into, a hot rolling mill.
Combining the casting and rolling operations can result in significant energy and cost savings over other casting processes which incorporate intermediate cast and reheat steps.
Metals cast on twin-belt continuous casting machines: Copper Bar, Strip, Anode , Aluminum Strip , Zinc Strip , Lead Strip Production rates and speeds: Twin-belt continuous casting rates range up to 60 tons per hour at speeds up to 14 meters per minute.
Twin-belt continuous casting is a near net shape casting process, which significantly reduces the need for secondary rolling or forming operations.
For example, when casting copper anode plate the cast slab is not rolled but rather sheared directly into distinct anode plates. The cooling belts are typically made of low carbon steel and are held under tension within the casting machine to ensure flatness and accuracy. As a "cold" belt enters the mold region, it is heated in the cast zone and is subject to powerful forces caused by thermal expansion.
When casting wide strip, these forces must be controlled to eliminate buckling and reduce thermal distortion of the belt at the mold entrance. These forces can be controlled by preheating the belts before mold entry, or by magnetically stabilizing them once they have entered the mold. Induction heating coils can be used across the width to preheat each belt.
Otherwise, it can properly increase withdrawal speed and specific water flowrate for slab casting of steels without Nb to improve the productivity. As so far, a lot of scholars have tested and researched on hot ductility of many kinds of steels.
We can acquire these useful thermoplastic parameters from the literature when needed.
Even so, most secondary cooling control systems are difficult to adapt to so many kinds of steels produced by each caster in actual production, due to the difference cooling characteristics of steel grades, especially for new steel production. At the same time, the database is embedded in the secondary cooling control system in order to acquire the corresponding reference and guidance for different kinds of steels and set suitable target surface temperatures by means of querying data from the database.
Figure 2. The software interface of the database for hot ductility of steels The hot ductility of steel is mainly influenced by the chemical composition or technical conditions.
Thus, the mathematical model has been established for predicting the reduction of area with chemical composition. The multiple linear regression analysis method has been applied to this model, which was conducted from 24 groups tested data in the similar experiment condition. Moreover, the model considers 12 elements as the independent variables and the reduction of area as the dependent variable.