Secondary Cooling Technology in Continuous Casting Process Jul31

Secondary Cooling Technology in Continuous Casting Process...

Secondary Cooling Technology in Continuous Casting Process  A wide range of steel grades ranging from ultra low carbon (ULC) and low carbon grades to high carbon and different grades of special steels are required to be cast in continuous casting machine (CCM). The casting of these grades is to be achieved while maximizing CCM output. Consistent production of prime quality cast steel product requires increased operational and maintenance flexibility in the CCM for maintaining optimum casting parameters can be maintained. This flexibility is needed both for every element as well as control system of CCM. While the strand is continuously withdrawn at the casting speed, solidification of steel continues beneath the mould through the different zones of cooling having a series of water sprays. The secondary cooling system consists of these different zones, each responsible for a segment of controlled cooling of the solidifying strand as it progresses through the CCM. The sprayed medium is either water or a combination of air and water (mist spray cooling). Mist spray cooling provides the following advantages. Uniform cooling Less water requirement Reduced surface cracking Product quality in a CCM is considerably influenced by temperature variations during strand cooling in secondary cooling zone. Hence secondary cooling zone has a very important function for the maintenance of a correct temperature parameter and is crucial to the quality of the cast steel product. Since the quality of steel depends on the behavior of the surface temperature and the solidification of steel front in time, it is to a large extent defined by the intensity of the water sprays. Improper cooling conditions can have detrimental impact on stress distribution in solidified shell. First of all, overcooling can lead to the formation of cracks. Moreover, there must be a smooth transition...

Beam Blank Casting Technology May14

Beam Blank Casting Technology...

Beam Blank Casting Technology The development of the direct casting of beam blanks is one of the most outstanding success stories in the evolution of the continuous casting of steel. The continuous casting of near net shape cross sections, called ‘beam blanks’ or ‘dogbones’, has been an efficient commercial process to manufacture long steel products such as I and H beams since the first beam blank caster was commissioned at Algoma Steel (now Essar Steel Algoma Inc., Sault Ste. Marie, Canada) in 1968. Its economics over conventional bloom casting are due to higher productivity, lower rolling costs and improved energy efficiency. As with many other innovations, the relatively conservative steel industry needed some time to accept this revolutionary concept. Its successful application depended on the inter-disciplinary co-operation and on the optimizing of casting and rolling process. This pioneering effort immediately attracted wide interest not only in the steel industry, but also by academia, e.g., in studying the solidification pattern of this complex strand shape. Nevertheless, it took another five years until the next beam blank caster got off the ground at Mizushima works of Kawasaki Steel Corporation. Continuous casting and rolling of beam blank has become a common practice in the steel beam production. Development in recent years concentrates in casting near net shape beam blanks. The difference between the conventional and near net shape beam blank is showed in Fig. 1. Conventional beam blank has a relatively thicker flange, usually over 100 mm, while the near net shape beam blank has a flange thickness less than 100 mm, usually with a lower limit 50 mm in the practice. Dozens, even a hundred beams can be produced through rolling only one beam blank. Fig 1 Conventional and near net shape beam blanks Beam blank...

Electromagnetic Stirring in Continuous Casting Process Nov29

Electromagnetic Stirring in Continuous Casting Process...

Electromagnetic Stirring in Continuous Casting Process Since the first application of the principle of continuous casting to steel in the test continuous casting machine of Junghans of former West Germany, the quality of the continuous cast product has been paid more and more attention. In recent years with the stress on the production of clean steels, there are higher requirements for the microstructure and the composition homogenization of the cast product. The chemical composition, solidification conditions and the nature of the liquid steel flow in the mould affects the surface quality and the inner structure of the cast product. The application of electromagnetic stirring (EMS) technique promotes the formation of an equiaxed crystallic zone in the strand. It causes the refinement of the solidification structure, the reduction in the content of inclusions and improvement in the quality of the surface, sub surface and the inner structure of the cast product. Principle of electromagnetic stirring It is well known that an alternating magnetic field (B) (either single phase, two phase or three phase) applied to a conductor, whether solid or fluid, will induce electric current (j) in the conductor, and hence there is a force (F = j x B). This force is known as Lorentz force. Due to the Lorentz force there is a generation of a torque that gives the liquid steel a rotational movement.  The generated torque depends on the following factors. Intensity of supply current Number of windings forming a coil Frequency System geometry These parameters change depending on the stirrer type. Thus the magnetic field acts as a non intrusive stirring device and it can, in principle, be engineered to provide any desired pattern of stirring. The stirrer design, size and position etc. depend on the continuous casting machine data,...

Steel Wire Ropes

Steel Wire Ropes Steel wire rope, is also known as steel cable.  It is a type of rope which consists of several strands of steel wire laid (twisted) into a helix. Modern wire rope was invented by the German mining engineer Wilhelm Albert in the years between 1831 and 1834 for use in mining. It was quickly accepted because it proved superior to metal chains and ropes made of hemp which was used before. Wilhelm Albert’s first ropes consisted of three strands consisting of four wires each. Wire rope industry in India, which was founded very early, started with coconut fibre ropes, switched to jute fibre, on to ‘Manila’ ropes and then to steel ropes. With the change in the needs, the designing of the wire ropes also undergone major changes with respect to the core, overlay and the weight requirement etc. Wire rope is a machine which consists of a number of precise moving parts, designed and manufactured to bear a definite relation to one another. In fact, some wire ropes contain more moving parts than many complicated mechanisms. For example, a six strand wire rope, laid around and independent wire rope core each strand and core with 49 wires, contains a total of 343 individual wires. All these wires are to work together and move with respect to one another if the rope is to have the flexibility necessary for successful operation. Wire rope has three components (Fig 1) consisting of wires, strands and core. The basic unit of a wire rope is wire which is carefully processed and drawn from selected grades of steel to predetermined physical properties and sizes. A predetermined number of finished wires are helically laid together in a uniform geometric pattern to form a strand. The process is carried out with precision and...