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By Marco A. Ramírez-Argáez

A 2D mathematical model was developed for the plasma arc welding process. Computational simulations based on mass and momentum conservation equations as well as Maxwell equations were performed by using the commercial software PHOENICS. The model predicts the electric characteristics of the arc column, flow patterns, temperature contours and electrical potential, by varying the composition of the cover gas, in this case, argon and nitrogen. It was found that an arc of nitrogen with respect to one of argon generates more intense jets, greater voltages, and lower temperatures in the arc column for welding arcs current of 150 A and 10 mm arc length.

Oct 30, 2017

By Eric Schaub

Hot Blast Stove Systems are an important equipment of a Blast Furnace plant. During the last years, performance requirements and operation practice for the Hot Blast Systems have changed and have a big influence on the Blast Furnace operation. Therefore it is necessary to keep the Hot Blast System in proper condition in order to maintain the production capacity of the Blast Furnace. It is important for operators to know the condition and relevant constrains of a Hot Blast Stove Plant. Assessing its condition on a regular basis, especially in advance of a Blast Furnace relining is therefore advisable. Considering the individual condition of the Hot Blast Stove Plant, improvements in operation, but also specific and dedicated repairs might be implemented. Design improvements can be implemented as well during such repairs. This paper will describe some of these design improvements, will illustrate their implementation in new hot blast stoves but will also describe repair methods for existing stoves. In addition new developments became popular during the last decade, like the so called Dome Combustion Stoves, which was invented already 30 years ago in Western Europe. Paul Wurth’s development in this regard will be discussed in this paper as well.

Oct 30, 2017

By John Hinton

Electromagnetic based (EM) sensor technology has been shown to detect changes in the magnetic permeability of steel strip travelling down the run out table after rolling. Measuring below the Curie temperature, these changes can be interpreted in terms of the phase transformation from austenite (paramagnetic) to ferrite (ferromagnetic). These real time measurements provide a detailed insight into the changes in the structure at high temperature providing the steel producer with feedback on quality control, product consistency and product development. However unlike mill microstructure models, the sensor measurement provides a point reading at a distance through the cooling course. To map the transformation in more detail, a sensor array is required along the length of the Run Out Table i.e. to measure points on the austenite to ferrite transformation curve. This paper describes the process and metallurgical factors that should be considered in the optimum design of a sensor array, i.e. the number and location of the sensor heads. Examples of cooling strategies for different steel grades e.g. low carbon, structural and dual phase steels are used to demonstrate the importance of sensor location. In addition, the effect of variability within typical industrial parameters e.g. cooling speed, on the sensitivity of sensor output and location will be considered.

Oct 1, 2019

By Armando Vazquez

Steel Dynamics Inc. (SDI) and Tenova Goodfellow Inc. (TGI) have successfully commissioned the first hybrid extractive/laser system for continuous and full spectrum analysis (CO, CO2, O2, H2 and H2O vapor) on two twin shell furnaces at Butler, Indiana. NextGen® technology using off-gas analysis as a main tool for EAF practice optimization is a proven effective method for improving plant productivity. Significant benefits attributed to the NextGen® system are operational cost reductions through the use of real-time dynamic control of chemical energy and improved environmental conditions through reduced GHG emissions. Additionally, the implementation of Tenova’s Water Leak Detection Technology® has shown results as an effective tool for operators to identify in real-time the presence of water during both reducing and oxidizing conditions. This paper will include project details, trials and results and will also outline the latest hardware developments and multipoint capabilities

Oct 30, 2017

By Alexander Fleischanderl

Steel market has become somehow unpredictable and requires quick adjustment in production conditions to survive in the harsh market environment. Steel production is not anymore driven by output records, but by efficient cost reduction measures to remain competitive under strongly varying production conditions. Energy efficient production and flexible raw material scenarios have become decisive factors to succeed and survive in our industry. Such scenarios have to be carefully investigated to be well prepared to adopt production steps continuously. The paper analyses various process opportunities to optimize energy and raw material consumption in the production route. Off-gas treatment systems have still a huge untapped potential to recover energy from the hot waste gases. This is valid for the EAF mini mills as well as for the integrated route. Various examples for waste heat recovery systems including resulting benefits are discussed for the EAF, agglomeration, blast furnace, direct reduction and BOF. New innovative bag-filter systems feature extremely low emission levels at lowest pressure loss and sound emission conditions. Also improved control and automation solutions support the operators to minimize the operation and maintenance costs of their off-gas system. Steelmaking by-products shall not be considered as residues, but as a valuable and cheap raw material source. The paper presents some show cases how to valorize slags as well as utilizing coke and iron oxide fines to increase productivity and minimize raw material cost. A new process for highly flexible converter steelmaking allowing for extraordinary high HBI and scrap rates above 50% and improved yield is discussed and evaluated

Oct 30, 2017

By Giulio Rodrigues Altoé

The environmental concern is creating pressure for the substitution of high energy consumption materials for natural and sustainable ones. Compared to synthetic fibers, natural fibers have shown advantages in technical aspects such as flexibility and toughness. So there is a growing worldwide interest in the use of these fibers. PALF extracted from pineapple leaves, presents some significant characteristic, but until now only few studies on PALF were performed. This work aims to make the analysis of the tensile strength of polyester composites reinforced with PALF. The fibers were incorporated into the polyester matrix with volume fraction from 0 to 30%. After fracture the specimens were analyzed by a SEM (scanning electron microscope).

Aug 16, 2017

By Li Shanqing, Xu Jianghua, Li Hongmei, Huang Peijie

Cold rolled high strength steel are playing a very important role in reducing automobile weight for energy saving and environment protection. In recent year, more and more high strength steel were manufacturing in steel company. But there are some problems in the cold rolling process for high strength steel products. Periodic thickness deviation especially in strip head or tail is an important one in these problems. In this paper, the reason of periodic thickness deviation was analysed and a new AGC algorithm called Property FFC for high strength steel in tandem cold rolling was developed. The application of this new algorithm shows that it can reduce the thickness deviation.

Oct 1, 2019

By Stefan Thelen

In November 2013 Salzgitter restarted their tandem mill after two weeks of shutdown, during which the existing mill entry equipment has been removed and replaced by new entry area equipment including pay-off reels, welding machine and a vertical entry looper for continuous feeding of the 5-stand tandem mill. It turned out to be beneficial to both product quality and production capacity.

Aug 16, 2017

By Matteo Tomba

Today’s steel market is characterised by high competitiveness and tight profit margins; therefore, the operational costs of rolling mills must be as low as possible, while ensuring a final product of the highest quality standards. PERT SRL is an engineering company with a long-term experience in the international steel market, specialised in the design and supply of highly innovative and bespoke solutions for siderurgical and environmental plants. Because of its strong commitment to deliver excellent products and services, and its ability to innovate and adapt to the fastchanging market requirements, PERT has studied a new generation of BI-SUPPORT rolling stands, designed to be used in rolling mill plants for the production of rebars, rounds and sections in special quality bars (SBQ) steel grade, wire rod, light and medium section, suitable also for special steel plants. This paper will provide a deep insight into the key technical and economic features that have revolutionised the rolling technology for long products, such as the absence of spindles and piping on board, the considerably reduced number of spare parts required, a ring gap regulation system, and the compact dimensions, which lead to significant savings in investments and production costs; at the same time, the BI-SUPPORT stands guarantee excellent standards to the final product, an increase in plant productivity and a general improvement in the plant management.

Aug 16, 2017

By Delio Amorim

Industry 4.0 concepts is the new biggest challenge on the industry nowadays and every company in every industry in every part of the globe is looking to implement this somehow on their factories and machines. To do that on the newest long rolling mills, that brings already onboard state-of-the-art technologies, is for sure a challenge of machinery builder industry, but how to become the long rolling mills built on 70’s, 80’s or 90’s part of this innovation process and connected to the new trends? This is the main mission here, to show some examples of applications that goes in this direction.

Oct 1, 2019

By Piotr Kula

Vacuum carburising with pre-nitriding (PreNitLPC® technology) involves feeding ammonia during the charge heating stage before carburising. The purpose is to restrict the growth of grain in the surface layer of the carburised steel. The article presents the influence of nitrogen on restricting austenite grain growth during vacuum carburising and on mechanical properties (fatigue strength, impact resistance) of layers that underwent such treatment in comparison with traditional carburising methods.

Aug 16, 2017

By D. A. Aranda-Regino, C. Gómez-de-la-Garza, J. Ramírez-Cuellar, L. A. Leduc-Lezama

The Pickling Line Tandem Cold Mill (PLTCM) at Ternium’s Pesqueria plant with a 5 stands, 6 high configuration started in 2013. At the time of the start up the work roll specification and grinding practices were stablished following a low risk policy to be able to sustain any start-up associated accident. Once a stable operation has been achieved both these policies are being modified to improve productivity and reduce costs. The specified hardness of the rolls has been increased and efforts are being made to optimize the grinding according to the rolling campaign length and materials. The fatigue damage in work rolls, after rolling and its removal by grinding was followed by hardness measurements made at the end of the rolling campaign and after grinding. Softening of the rolls after rolling was found mainly in final stands to be related to the averaged stress experienced during the campaign, the original roll hardness was recovered after grinding. Hardness evolution was also followed after each grinding step finding that the total amount of grinding could be reduced. The grinding practice was modified accordingly for the first stands and the yield of work rolls in them has improved.

Oct 1, 2019

By Márcia Maria da Silva Monteiro Pereira

Durante o lingotamento contínuo de aço, partículas de ZrO2 adicionadas na escória de molde facilitam a nucleação heterogênea de cristais devido à sua limitada solubilidade. A adição de ZrO2 promove a cristalização da fase cuspidina, o que auxilia na redução da transferência horizontal de calor no molde, amenizando desta forma o problema das trincas longitudinais. Outro benefício da adição de ZrO2 em pós fluxantes é reduzir a taxa de desgaste da válvula submersa (SEN) na interface metal/escória; a erosão da SEN é um problema sério. Através de testes de laboratório e de testes industriais concluiu-se que a adição de ZrO2 em pós fluxantes reduz a taxa de transferência de calor horizontal no molde durante o lingotamento contínuo de aço, considerando os dois tipos de pós fluxantes que foram analisados no presente trabalho. Além disso, observou-se que a adição de ZrO2 reduz a taxa de desgaste da válvula submersa na interface metal/escória.

Aug 16, 2017

By Giuseppe Pintaude

This study aims to evaluate the effect of specimen preparation on the dry sliding wear behavior of CA-6 NM stainless steel. Two different surface finishing manufacturing processes were applied: lapping and metallographic polishing. The wear tests were conducted in reciprocating ball-on-flat system, performed for two loads: 5 or 8 N. For all test conditions, hardmetal ball was employed as counterbody. The surfaces were evaluated using 3D interferometry technique to determine their surface roughness, including texture analysis regarding isotropy. Surface characterization results indicated the presence of texturing and preferential orientation, since the parameter Str was smaller than 0.5 for samples of both the studied conditions. Two distinct levels of isotropy evaluated through Str parameter were achieved: 0.13 for lapping and 0.3 for metallographic polishing process. It is clear from wear tests that the variation of average surface roughness is the key point for tribological behavior of CA-6 NM stainless steel.

Jul 31, 2018

By Christoph Aichinger

A smart combination – Primetals Technologies developed the Circular Pelletizing Technology (CPT), which is a combination of the well-proven travelling-grate pelletizing technology with the design of a circular dip rail cooler of modern sinter plants. The overall space requirement and the installed weight for a CPT plant is significantly less compared to conventional technologies and by that CPT is a very attractive alternative for new projects.

Aug 16, 2017

By Marjorie Benegra

This study aims to compare the wear resistance assessed in rubber wheel abrasion test of nickel aluminide coatings deposited by for Plasma Transferred Arc (PTA) and High Velocity Oxigen Fuel (HVOF) manufacturing, using the same raw material. A nickel aluminide powder was atomized and deposited on 316L steel plate substrate. After deposition, some specimens were submitted to a heat treating (1200 °C for 24 h followed by 760°C for 24 h). The coatings deposited using PTA developed different microstructures due to the incorporation of substrate elements, its performance was better than the HVOF coatings, although their Vickers hardness was similar. After heat treating, a significant variation in hardness and wear resistance was observed. For PTA specimens, there were decrease in hardness of 35%, while for HVOF ones this drop was approximately 20%. Nonetheless, the effect of thermal exposure in wear resistance was quite different: an increase of 21% was observed for HVOF coatings, while a reduction of 20% occurred in PTA ones. Microstructures modifications in PTA coatings were significant for their wear resistance. On the other hand, the reduction of porosity and sintering were responsible for a better performance of heat-treated HVOF coatings.

Jul 31, 2018

By Edo Engel

Blast furnace No. 3 at Zaporizhstal in Zaporozhye is rebuilt in 2016-2017. The Ukrainian company is targeting increased production and availability, mainly through the use of new technology. Zaporizhstal awarded a contract for a new Top Charging Unit to Danieli Corus, after comparing all available technologies. Reliability of the chosen charging device is pivotal, since long outages may be required for maintenance/replacement jobs, which strongly affects the availability of the blast furnace. This article describes the Top Charging Unit including DANCU (Danieli Charging Unit) - a robust hydraulic system. The main focus employed by Danieli and Danieli Corus during the development of this system has been availability and maintainability of equipment. This chute type charging unit has only few major moving parts, none of which is complex or vulnerable. The article also describes the main challenges of the project at Zaporizhstal, such as the use of hot sinter.

Oct 30, 2017

By Andrea Donadon

This article introduces the Danieli Total Asset Management System, which involves 360 degrees service methods and equipment. Danieli Condition Monitoring System and Danieli Torque Monitoring System are fundamental to evaluate the conditions of the working components in heavy duty transmissions. The first one monitors the vibrations and the lubrication fluid conditions with the purpose to identify the presence of malfunctions, by detecting any variation of the signals from the standard values. The second one monitors the transmitted torque for each spindle and gearbox, with the aim of detecting any anomaly in torque distribution and magnitude, and evaluating the residual life of the mechanical parts, on the base of a dedicated fatigue damage algorithm. All these features are useful in avoiding serious damages to machines, facilities and people, but allow also planning the maintenance and overhaul activities with efficiency, in order to achieve the best plant availability and reliability. The data analysis is made by the IntelliCMS software, which interfaces with plant and Danieli operators and includes the possibility to cooperate by remote connections, simplifying service activities and support. All these features allow providing new full service programs, where the client is totally supported in maintenance, overhauls and substitutions. This is the best way to ensure the most efficient, high quality and reliable after sales assistance.

Aug 16, 2017

By Jörg Busch

The essential pre-requisite for attaining the high quality of product required from high-speed continuous production processes is the use of new measurement and control technologies. High availability and reproducible measuring results ensure the high level of process stability necessary for full continuous operation. The requirements for the optimisation of quality across the complete production process and for quality analysis systems will be discussed. This report will present examples of basic and new measurement technologies in Cold Rolling Mills and Processing Lines. The following gauging systems will be discussed in detail: Strip tension meter, roll force measurements, weighing systems and shapemeter rolls. The measuring and control systems in this presentation must be seen as high-tech solutions in the field of processing technology. The measuring methods and technologies described are, together with optimised process models and precision control loops and actuators, the main pre-requisites for achieving the quality of product required from high-speed continuous production processes. Interconnected quality management systems enable optimisation across the complete production process.

Jul 30, 2018

By Jean Viana Bahia, Antônio Adel dos Santos, Vicente Tadeu Lopes Buono

During cold rolling of Cr-Mo alloyed DP steel, considerable oscillation of thickness may occur. The literature points out that such occurrence is due to non-uniform cooling of the coil after the hot rolling process. Since the austenite transformation in this steel continues after coiling, the microstructure and, consequently, mechanical properties are very susceptible to natural variations in cooling rates associated with distinct positions of the coil. The influence of coil cooling conditions on thickness oscillation during cold rolling was evaluated in this work by using both industrial experiments and dilatometer tests. It was verified that an industrial coil presented large variation of mechanical properties associated with its heterogeneous microstructure. Consequently, thickness oscillation occurred during cold rolling. Dilatometer tests simulating hot run-out table and coil cooling showed that the austenite transformation is very slow under small cooling rates that occur after coiling. Thus, the slow transformation rate makes the coil very susceptible to environmental conditions around it during its natural cooling and is responsible for variation in mechanical properties of the coil. To ensure the formation of a more homogeneous microstructure in the whole coil, it is necessary either to make use of technologies that improves the cooling uniformity or to adjust the steel alloy design. The latter alternative has been done with relative success by using conceptions with lower amounts of Cr and Mo.

Oct 1, 2019