Flat Rolled Steel Research Articles

Mechanism of Improved Ductility of 1500 MPa-class Ultra-high Strength Cold-rolled Steel Sheet Produced by Rolling and Partitioning Method

By using a steel with standardized chemical composition and conventional manufacturing processes for flat-rolled steel strip, a 1500 MPa class stainless steel sheet, whose product of yield strength (YS) and total elongation (El) exceeds 30000 MPa%, was developed and its mass production was established. Besides the excellent YS–El balance, the developed steel sheet has excellent performance for not only an anti-secondary work embrittlement but also high cycle fatigue endurance.

Indonesia – Safeguard on Certain Iron or Steel Products

AbstractIn July 2014, Indonesia implemented a safeguard tariff on galvalume, a type of galvanized flat-rolled steel. Chinese Taipei and Viet Nam challenged the measure, mainly claiming that Indonesia's administering authority failed to satisfy various substantive and procedural requirements of the GATT 1994 and the Safeguards Agreement. The Panel and AB found that the tariff was not a safeguard measure but rather was a simple increase in Indonesia's applied rate. Interestingly, Viet Nam, the largest import supplier, is a member of a free trade area with Indonesia, meaning Viet Nam is not subject to the MFN rate. Viet Nam's preferential tariff treatment likely influenced Indonesia's decision to claim the action was a safeguard. Ironically, even though the Appellate Body essentially rejected its claims, the ruling benefits Viet Nam.

Molybdenum alloying in high-performance flat-rolled steel grades

Considerable progress in developing flat-rolled steel grades has been made by the Chinese steel industry over the recent two decades. The increasing demand for high-performance products to be used in infrastructural projects as well as in production of consumer and capital goods has been driving this development until today. The installation of state-of-the-art steel making and rolling facilities has provided the possibility of processing the most advanced steel grades. The production of high-performance steel grades relies on specific alloying elements of which molybdenum is one of the most powerful. China is nearly self-sufficient in molybdenum supplies. This paper highlights the potential and advantages of molybdenum alloying over the entire range of flat-rolled steel products. Specific aspects of steel property improvement with respect to particular applications are indicated.

Studies on applying hot-rolled coil to hull superstructure

Application of the hot-rolled steel sheet for the members of superstructure, where the strength requirement of these parts in ships is not severe, is expected as a solution to reduce the hull construction cost. Because the hot-rolled steel sheet is applied after recoiling by cold working to return it to a flat plate, the material properties is deteriorated due to excessive plastic working and the residual stress induced by the plastic work might affect for the thermal cutting and welding. There is a possibility that the hot-rolled steel sheet has poor properties comparing with the flat rolled steels applied for hull parts where the structural integrities are required by the classification societies’ rules. The difference of properties between the hot-rolled steel sheet and the flat rolled steel are investigated in this research.

Deformation Behaviors of Flat Rolled Wire in Twinning-Induced Plasticity Steel

The influence of room temperature flat rolling on microstructure, mechanical properties, and shape change in twinning-induced plasticity (TWIP) steel wire has been investigated to understand the deformation behaviors of flat rolled wire in TWIP steel and to apply TWIP steels to flat rolled wire products. Numerical simulation, hardness test, and EBSD techniques were used to analyze the distribution of strain, mechanical properties, and microstructure of flat rolled TWIP steel wire. The shape of flat rolled TWIP steel wire was also evaluated and compared with plain carbon steels having low strain hardening rate. A very different behavior of hardness, strain, twinning, and KAM value was observed with area of flat rolled wire due to the different stress state and strain with area of wire. The center area had the maximum twin density, KAM value, effective strain, and hardness; whereas free surface area had the minimum values. The hardness inhomogeneity factor (HIF) along the horizontal direction was much higher in comparison with that of the vertical direction. The maximum HIF value occurred at the specific reduction in height, i.e., 27%. This means HIF value gradually increased and then decreased with reduction in height, which is inconsistent with the results of plain carbon steel and Cu wire. The lateral spread and width of contact area of flat rolled TWIP steel wire were lower than those of plain carbon steels, indicating that material properties such as strain hardening exponent are crucial parameters that influence the shape of flat rolled wire products.

State of production sheet steel rolled stock in the world and tendencies of development of cold strip rolling mills

The conditions of production and the most relevant directions of development of technology and equipment of cold rolling mills for the production of thin flat rolled steel are investigated, analyzed and summarized. A comparative analysis of cold rolling technology is carried out, which is implemented in continuous and reversed modes of mill. The technological limitations and criteria for the development of deformation modes on cold rolling strip mills, which allow to expand the assortment towards a smaller thickness, are given. A method for determining the thickness is proposed, and a series of thicknesses of thin (1.5-1.8 mm) hot-rolled break-down are recommended for the production of tinplate of single rolling and thin strips of high quality. The method of calculation schedule drafting on a specific mill is developed. The technique of determination of the smallest thickness of a strip on a concrete mill is presented, taking into account the influence of rigidity of the working cage and features of the force load of the roller node with a decrease in the thickness and width of the strip. The use of the above materials allows to select and justify the optimal variant of cold band rolling technology, as well as to develop rational deformation modes that ensure the implementation of the cold rolling process with maximum efficiency, given the desired range and the required volume of thin cold-rolled sheet steel or tinplate. As a result of taking into account the features of the force interaction of the thin strip with the rolls during cold rolling and the rigidity of the working stands of the mill, the accuracy and reliability of determining the parameters are increased, it opens additional possibilities for expanding the range of cold rolling mills towards smaller thicknesses.

Indonesia – Safeguard on Certain Iron or Steel Products: If It Looks Like a Duck, Swims Like a Duck, and Quacks Like a Duck, Then It Is Not a Duck

In July 2014 Indonesia implemented a safeguard tariff on galvalume, a type of galvanized flat-rolled steel. Chinese Taipei and Viet Nam challenged the measure, mainly claiming that Indonesia’s administering authority failed to satisfy various substantive and procedural requirements of the GATT 1994 and the Safeguards Agreement. The Panel and AB found that the tariff was not a safeguard measure but rather was a simple increase in Indonesia’s applied rate. Interestingly, Viet Nam, the largest import supplier, is a member of a free trade area with Indonesia, meaning Viet Nam is not subject to the MFN rate. Viet Nam’s preferential tariff treatment likely influenced Indonesia’s decision to claim the action was a safeguard. Ironically, even though the Appellate Body essentially rejected its claims, the ruling benefits Viet Nam.

Some approaches to improve the resource efficiency of production of flat rolled steel

Some approaches to improve the resource efficiency of production of flat rolled steel

Review of vision-based steel surface inspection systems

Steel is the material of choice for a large number and very diverse industrial applications. Surface qualities along with other properties are the most important quality parameters, particularly for flat-rolled steel products. Traditional manual surface inspection procedures are awfully inadequate to ensure guaranteed quality-free surface. To ensure stringent requirements of customers, automated vision-based steel surface inspection techniques have been found to be very effective and popular during the last two decades. Considering its importance, this paper attempts to make the first formal review of state-of-art of vision-based defect detection and classification of steel surfaces as they are produced from steel mills. It is observed that majority of research work has been undertaken for cold steel strip surfaces which is most sensitive to customers' requirements. Work on surface defect detection of hot strips and bars/rods has also shown signs of increase during the last 10 years. The review covers overall aspects of automatic steel surface defect detection and classification systems using vision-based techniques. Attentions have also been drawn to reported success rates along with issues related to real-time operational aspects.

Hybrid Modeling of Flat Rolling Process during Hot Rolling

Mathematical Modeling is an effective technique for prediction of process parameters in industrial processes. Artificial Neural Network (ANN) technique has also been used to recognize a pattern in the given data by training itself. Further the trained network is used for future prediction of process parameters on the basis of the pattern recognition. The mathematical models are based on some ideal assumptions which are not valid in practical industrial conditions. Similarly high variability in industrial data makes pattern recognition difficult for ANN models and leads to high errors of prediction. In the present work, an attempt has been made to develop a hybrid model by integrating two mathematical models and ANN model for prediction of roll force during hot rolling of flat rolled steel products. The mathematical equations for roll force have been derived from the pressure distribution equation derived by Sims and Tselikov. A feed-forward network with back-propagation algorithm has been selected for ANN. All the three methods have been converted into computer code using Visual Basic.Net programming language. The hybrid model has been trained with about 2500 hot rolled steel coil data collected from Bokaro Steel Plant and Rourkela Steel Plant consisting of three different steel grades. The hybrid model has been validated with measured data of about 1000 coils. Combinations of ANN network in hybrid model having different number of hidden neurons and learning rate have been formulated, trained and validated. The final hybrid model has been selected from these combinations which has maximum accuracy. Also Multi-variable optimization technique can be used to find out the values for various input conditions which affect the flow stress and the roll force, minimizing the Root Mean Square Error. When comparing the root mean square error (RMSE) of model, it has been found that the RMSE of hybrid model is about 25% less than that of Mathematical Model.

Machining Profiling of the Working Rolls as a Way to Control Cross-Section of the Rolled Steel

ncrease of requirements to quality of the flat-rolled steel causes the appearance of new methods and improvement of the well-known approaches to improving the geometry of thin-gage rolled steels. On modern rolling mills, control and management of the strips cross-section is carried out by a profile and flatness control system (PFC). The main channel of the influence of such systems on the geometric parameters of the rolled steel is the axial shifting of S-shaped working rolls in CVC (Continuous Variable Crown) mills. The performance of the PFC is determined by the correct choice of the initial (machining) profile of the working rolls. The paper discusses the way to improve the methodology of grinding S-shaped working rolls by taking into account the stresses, arising in the zone of contact strip with rolls, the elastic deformation of roll system, thermal deformations, arising from the contact with the hot strip and wear of the working layer of the rolls during the campaign. The developed mathematical model of stress-deformed state allows you to determine the places with the highest stresses in the zone of contact strip with working rolls and adjust the initial profile of the rolls to ensure uniformity of extracts of a strip in width with regard to shifting rolls in the axial direction. The mathematical model of the thermal condition of S-shaped rolls, which allows to predict the change of the rolls thermal profile, gives the possibility to create the algorithm for the grinding of the working rolls in hot condition and increase the accuracy of performance of their machining profile.

An airy function to rapidly predict stresses in wound metal strip having asymmetric thickness profile

With increased demand for thin gage flat metals, control of strip flatness or shape in cold rolling processes has become very important. To improve the flatness quality of cold rolled metal strip and sheet, this work provides a rapid method to predict the transient strains (or stresses) occurring during the rewinding of flat-rolled steels having problematic asymmetric strip thickness profile (or wedge). Flatness control systems, used to monitor and correct the distribution of stress across the width of rolled sheet, are unable to distinguish between stresses induced during rolling, and those caused when rewinding strip containing asymmetric thickness profile. The winding stresses, unless large enough to plastically deform the strip, vanish upon unwinding during subsequent operations such as stamping. Therefore, to help avoid strip flatness defects in thin strip containing wedge, a method is developed to separate the winding stress contribution from the overall stresses that are measured indirectly by flatness control systems. A fourth-order polynomial Airy function is developed to rapidly predict the in-plane stresses based on mandrel wrap number and spatial location on the strip. The Airy function is obtained by applying two-dimensional finite element analysis to study the transient in-plane stresses during rewinding at various numbers of mandrel wraps for a strip containing wedge profile. Three-dimensional finite element analysis is first employed, however, to show justification to a simplified two-dimensional problem described by the plane-stress Airy function. The two-dimensional finite element analysis provides insight as to how the in-plane stresses evolve, and allows determination of coefficients for the Airy function based upon model geometry and displacement boundary conditions. This approach differs from other methods that employ Fourier series to solve the biharmonic equations for an assumed two-dimensional problem. Finally, filtering of the winding stresses from flatness control system input signals is also discussed based on data taken from a rolling mill different to that used for model development.

Texture evolution in low-C flat rolled steels on the physical properties

Texture evolution and physical properties are studied to investigate effects according to recrystallization treatment and the reduction ratio of temper rolling. Cold rolling texture can be decided by the deformation criteria and slip systems. Texture components develop by different deformation hysteresis in the surface and center layer of low-C flat rolled steels. Predominant γ-fiber is developed by cold rolling in center layer and (α+γ)-fibers which α-fiber is strong are developed in surface layer. This is the result of the different deformation hysteresis of the surface and center layer. After recrystallization the intensity of γ-fiber is clearly developed. γ-fiber is well developed in IF steel, but strong α-fiber together with γ-fiber is developed in AK steel. This is because textures having orientation scattering from γ-fiber are developed from recovery detention by the reaction between carbon and dislocations, inhomogeneity of slip behavior by carbon atoms, and plastic deformation mechanism like slip bands, etc. High permeability and low coercivity can be obtained by developing texture parallel to magnetic easy axis {hkl}〈100〉. Factors having effects on magnetic properties are grain size, chemical composition, texture, etc.

A Partial Equilibrium Approach of Modeling Vertical Linkages in the U.S. Flat Rolled Steel Market

This paper models linkages between upstream and downstream goods in the U.S. market for flat-rolled steel. These vertical linkages are important to account for when estimating the impact of trade restrictions on imports of flat rolled steel because some types of flat rolled steel are predominately used to produce other types of flat rolled steel and in some cases also make up a large share of their production costs. Previous research has modeled the linkages between upstream and downstream goods with CGE models and vertically linked partial equilibrium models. Drawing upon this literature, this paper builds a vertically linked version of the CES COMPAS model that incorporates vertical linkages as constant cross price elasticities in both downstream supply functions and upstream factor demand functions. Compared to estimates from the CES COMPAS without vertical linkages, introduction of a trade restriction increases demand for upstream goods and decreases supply of downstream goods, increasing prices of both upstream and downstream goods, while increasing shipments of upstream goods and decreasing shipments of downstream goods. In estimating the impact of the safeguard measures imposed on the flat rolled steel market, accounting for the vertical linkages is most important when estimating the impact on domestically produced slab since all downstream products produced from slab were subject to the safeguard tariffs.

Development of High-Speed/High-Torque MR Actuator Using Silicon Steel Sheet

There are a lot of robot systems that directly touch and transmit the power to the users. Though it is very important that such robot systems are developed on consideration of safety, most of them are developed without argument or with abstract argument about safety. In this paper, firstly, we insist that safety of a robot system using MR Actuator can be estimated quantitatively and ensured mechanically. Secondly, the development of the High-Speed/High-Torque MR actuator is described. Response characteristics of the developed MR actuator are improved by using flat rolled silicon steel sheet. And lastly, basic characteristics of the new MR Actuator are demonstrated.

Composite-coated flat-rolled steel

Composite-coated flat-rolled steel

ARMCO 409 Ni

Abstract Armco 409 Ni is a fine-grain stainless steel developed for applications more than 0.120 in. thick needing an alloy superior to Type 409 stainless steels in weld formability and toughness. Applications include coal-handling equipment, transportation containers, mixers, liners, exhaust flanges, heat shields, and cyclones. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming and joining. Filing Code: SS-663. Producer or source: Armco Inc., Specialty Flat-Rolled Steels.

Determination of the optimum velocity of the suspension in hydroabrasive cleaning of scale from flat-rolled steel

Determination of the optimum velocity of the suspension in hydroabrasive cleaning of scale from flat-rolled steel

An automatic surface inspection system for flat rolled steel

The paper describes a feasibility study of on-line classification of visible defects in flat rolled steel, as the steel emerges from the rolling mill. A visual signal developed by a television camera is processed by a software simulation of the proposed hardware system which stores information from the scans and alerts a small computer when a possible flaw has been detected. A pattern recognition algorithm, executable by the computer, makes the final detection and classification decision before the next coil is rolled. A detailed simulation of the hardware using photographs of steel defects is presented.

Ultrasonic testing of flat rolled steel: Silber, F.A.Berg ünd Hüttenmännische Monatshefte, 110, No. 3, 66 (1965)

Ultrasonic testing of flat rolled steel: Silber, F.A.Berg ünd Hüttenmännische Monatshefte, 110, No. 3, 66 (1965)