Root cause analysis of surface cracks in heavy steel plates during the hot rolling process article pdf available in metals open access metallurgy journal 97. Simulations of the hot rolling of u10mo coupons encapsulated in lowcarbon steel have been conducted. There are certain types of the rolling process, whereas, in the hot rolling. Secondary scale on hot strip and the impact on wear is another issue.
Rolling process animation rolling mill machine concept. A rolling mill is a complex machine having two or more working rollers, supporting rollers, roll stands, drive motor, reducing gear, flywheel, coupling gear etc. The steel is processed further in cold reduction mills, where the material is cooled at room temperature followed by annealing andor tempers rolling. Steel rolling technology handbook 2nd revised edition. Rolling of metal auxiliary operations used in connection. Hot rolling technology rolling is classified according to the temperature of work piece rolled. Apart from that, another crucial significance of the rolling process is the least tolerance. Working, application, defects, type of rolling mills.
Hot rolling hot rolling is a metalworking process that occurs above the recrystallization temperature of the material. Companion volume to cold rolling of steel by william roberts circa 1978 and number two of the series. During hot rolling, three kinds of scales are possible. In order to reduce the roll force, we can reduce roll diameter, or. Accounts for 90% of all metals produced by metal working processes. Cold rollingis a rolling operation carried out at room temperature. Thanks to integrated process models todays demands for flexible and economic production of steel plate can only be met by electrical and automation solutions based on technological process modeling, highperformance control systems, and a comprehensive understanding of. Friction modelling of a hot rolling process by means of. Thorough account of the hotrolling process and facilities as well as followup treatments given to hotrolled products. Pdf in this paper, a real application of opti mal control of a hot rolling mill is presented. Rolls wear characterization in hot rolling process c. Hot rolling aluminum is hot rolled into a coil of desired thickness. The evolution of microstructure in hot rolling of aluminium alloys depends on the interaction of the main process parameters. Rolling is the process of reducing the thickness or changing the cross section of a long workpiece by compressive forces applied through a set of rolls, as shown in figure 51.
The primary function of the hot strip mill is to reheat semifinished steel slabs of steel nearly to their melting point, then roll them thinner and longer through 12 successive rolling mill stands driven by motors totaling 77,000 hp, and finally coiling up the lengthened steel sheet for transport to the next process. We guarantee that your information will not be divulged to the third party. Hot rolled metals generally have little directionality in their mechanical properties and deformation induced residual stresses. In the past it used to take weeks to produce coiled strip from iron ore. The process of shaping metals into semifinished or finished forms by passing between rollers is called rolling. The hot strip geometry and microstructure also affects the final sheet geometry and properties, also after final cold rolling, so special attention must be paid to the hot mill process. Rolling is a metal forming process in which metal is passed through a pair of rotating rolls for plastic deformation of the metall. The temperature of preheat of the ingot and the time held at that temperature is important for some alloys since a process of homogenisation takes place which renders the material in the. Its grains reform after the rolling process and it is left in a stressfree state. Cold rolling is commonly conducted after hot rolling when good surface quality and low thickness tolerance are needed.
In any particular metal rolling process, it is important to understand how these deflections will affect the rolls and hence the work being rolled. Rolling is the oldest metal working process after forging and today is the most commonly used method of deforming ascast metals into. After the grains deform during processing, they recrystallize, which maintains an equiaxed microstructure and prevents the metal from work hardening. Rolling is used for making hollow seamless tubes, rods etc. In flat rolling, the work is squeezed between two rolls so that its thickness is reduced by an amount called the draft. Rolling of workpiece can be carried out in hot or cold condition. Stresses from hertzian pressure in 4high cold mill back up rolls were measured years ago, the results were never published, but of high interest also, maybe later. Rolls will be subject to different degrees of deflection. Components produced through rolling have higher mechanical properties than cast products. The cold rolling process is carried out at low recrystallization temperature and it produces relevant small and thin pieces and temperature is low, therefore deformation becomes relatively difficult than the hot rolling process.
So tolerance for the shape at the hot rolling process is rather high. It is used the state space model formulation in the. Hot rolling is a process in a steel plant in which the semifinished slab is reheated to a predetermined temperature and the hot slab is rolled to make the specified hot strip in a coiled form. They are usually welded to the supporting steel members and can. Hotrolled process can significantly reduce consumption, reduce costs where it can be hotrolled billet should be hotrolled metal, because metal hot deformation resistance than coldrolled low, can significantly reduce energy consumption during rolling. Advanced process and quality control in hot rolling mills. Cold roll is processed below the recrystallization temperature.
Cold rolling can also reduce the grain size of the metal resulting in hallpetch hardening. Forging is one of the oldest known metalworking processes. Pdf rolls wear characterization in hot rolling process. In thinslab continuouscast rolling mills the strip rolled thickness is below 1 mm and the strip caster aims to cast between 2 and 1 mm. Rolling is the most widely used metal forming process. Hot working is plastically deforming of the metallic material at a temperature above the recrystallization temperature. Similarly, smaller reductions requires lower roll force. Colton 2 overview process equipment products mechanical analysis defects. This process is used to create shapes with the desired geometrical dimensions and material properties while maintaining the same volume of metal.
The hot rolling process california steel industries. Pdf root cause analysis of surface cracks in heavy steel. Rolling is classified according to the temperature of the metal rolled. The difference between the two is the temperature at which they are processed. On the possibility of looperless rolling on hot rolling. Scale formation and its removal in hot rolling process.
If the temperature of the metal is above its recrystallization temperature, then the process is termed as hot rolling. During the rolling process great forces act upon the rolls. Detection of periodic defects rolls and rollers are the most heavily used parts of a rolling mill. Hot rolling is a metalworking process in which metal is heated above the recrystallization temperature to plastically deform it in the working or rolling operation. Furthermore, it can be concluded that the metal forming process can be conducted at a low cost due to the rolling process. Number ten of the manufacturing engineering and material processing series.
After the steel has cooled, it is subjected to annealing andor tempers rolling, in order to provide a wide range of surface finishes and more accurate. The cold rolled process creates a finished product that is more precise dimensionally than a hot rolled. Report on best available techniques bat in the german. Rolling and processing papers from primetals technologies at the estad conference 2017 in vienna covering the topics of long rolling, plate mills, linked casting and rolling, hotstrip rolling, pickling, cold rolling, strip processing and the associated automation and processoptimization systems. Plate mill power meets precision primetals technologies. Hot rolling is a mill process which involves rolling the steel at a high temperature typically at a temperature over. Rolling is a metal forming process, in which stock of material is passed between one or more pairs of roller to reduce and maintain the uniform thickness.
Large length cross sections are produced by rolling process. Steel roof and floor deck panels are fabricated from sheet metal by further coldrolling into corrugated profiles four to eight centimetres 1. The rolling process allows close loop at a high speed that provides high and premium quality material. The starting material is usually large pieces of metal, like semifinished casting products, such as slabs, blooms, and. Overview of the steelmaking process pellets sinter limestone coke iron ore coal scrap blast furnace ironmaking converter steelmaking ladle refining blast furnace steelmaking coalnatural gas plate hotrolled bars rods tube rounds rails slab billet bloom hotrolled and coldrolled strip coils structural shapes. Evolution of microstructure during hot rolling of inconel. Hot rolling process in steelworks plays a role which rolls slabs casted at continuous casting in order to produce hot sheet coils. It is use for mass production of threaded parts like screw, bolts etc. Although rolls are refurbished in the roll shop regularly, they occasionally crack before the end of the usual production cycle. After being rolled, the steel is cooled at room temperature in cold reduction mills. Construction material, roofing panels, partition beams, railroads, etc. Forged steel rolls were also improved for cold rolling to give higher hardness penetration after heat treatment by increasing the content of alloying elements. Primary scale is formed during reheating process of the slabs in the pusher type or walking beam furnace.
Equipment picture 3 10 types of rolling based on workpiece geometry. The temperature at which atomic mobility can repair the damage caused by the working process. Hot rolling is a metalworking process that occurs above the recrystallization temperature of the material. Some of the hot sheet coils are shipped after rolled at cold rolling process in order to make cold sheet coils and the others are shipped as they are. Both hot rolling and cold rolling are used to create sheet metal. Cold rolling involves a similar process to hot rolling, however the steel is subjected to further processing. This makes cold rolling a more labor intensive and expensive process than hot rolling. Consider rolling of a flat plate in a 2high rolling mill. Hot rollingis a rolling operation carried out at a temperature just below the metal melting point, permitting large amount of deformation.
Flat rolling used to reduce thickness of a rectangular cross section shape rolling square cross section is formed into a shape. Cold rolled steel is essentially hot rolled steel that has had further processing. Fundamental concept of metal rolling 1 the arc of contact between the rolls and the metal is a part of a circle. Secondary scale is formed during the rolling process in the roughing mill area and. Slabs,sheets,bars,rods,structural components like i,u,l etc. Lci information on the hot rolling process was taken directly from althaus et al. In the conventional hot strip mills the minimum strip thickness rolled was 1,5 2 mm. For hot working processes, large deformation can be successively repeated, as the metal remains soft and ductile. If you have any questions or good suggestions on our products and site, or if you want to know more information about our products, please write them and send to us, we will contact you within one business day. Ugi engineering works private limited is one of the most prestigious manufacturer, exporter, supplier, and consultant of high grade hot rolling mill. We have seen that the rolling load is dependent on roll diameter, higher the roll dia, higher the roll force.
Hot roll is processed above the recrystallization temperature. Hot rolling most common due to the large amount of. Due to wear from contacting hot material with great force, their lifetime is limited. As hot rolling is a process with high energy consumption, norton results to be the more complete law for the simulation of rolling processes. Difference between hot and cold rolled steel metal.
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