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By Eduardo Dominguez Trindade

Lubricant oils are subjected to reciprocating movement in the piston ring/cylinder tribocouple of automotive engines. In this kind of movement, the relative speed oscillates between zero and a maximum, and therefore the lubrication regime goes from boundary to hydrodynamic. Tribotests are widely used in laboratories to hint at the friction developed in these systems. In the present work, a SRV tribometer was used to evaluate the friction behaviour of lubricant oils under reciprocating movement up to 60 Hz. A high acquisition rate allowed the analysis of data inside each reciprocating cycle. Both a pure base oil and a fully formulated lubricant were used. Changes in the contact pressure, viscosity and speed were seen to influence friction, which was correlated to the relative thickness predicted by Hamrock-Dowson equation. While some observed characteristics were typical consequences of the Stribeck curve, other effects were also observed, such as the occurrence of seizure at high reciprocating frequency. A lower boundary coefficient of friction due to additive package in the formulated oil was also observed. The results allow a better understanding of friction in reciprocating cycles and can be used to evaluate the performance of oils and surfaces in laboratory prior to engine testing.

Jul 31, 2018

By Gabriel Oliveira Glória

Due to growing concern about the ambient impacts, lignocellulosic fibers are been investigated to replace the synthetic ones in polymer composites The giant bamboo fiber, a relatively unknown lignocellulosic fiber with potential for composite reinforcement, still needs to characterize for possible engineer applications. However the giant bamboo fiber has low adhesion with the polymeric matrix. In order to understand the interaction that occurs between the bamboo fiber and the polymer matrix is necessary to evaluate its physical and chemical characteristics. Therefore, the present work analyzed the giant bamboo fiber by means of Fourier Transform Infrared (FTIR) spectroscopy. The spectrum revealed main absorption bands typical of giant bamboo fiber specific molecular interactions.

Aug 16, 2017

By Dalila Chaves Sicupira

A pitting corrosion study of welded joints of lean duplex stainless steel (LDSS) UNS S32304 has been performed. LDSS S32304 thick plates were welded by different processes commonly employed in equipment and piping construction: SMAW (Shielded metal arc welding), GMAW (Gas metal arc welding) and FCAW (Flux cored arc welding). The electrochemical behavior of different weldment zones (fusion zone (FZ), base metal (BM) and heat affected zone (HAZ)) was characterized both independently using an electrochemical microcell and together through whole sample analysis. The electrochemical method applied was performed in acidified glycerin, a process fluid of the biodiesel industry. The results were correlated to the microstructural features of the materials. Based on the results, is possible to conclude that the breakdown potential (Eb) of the fusion zone (FZ) was higher than the Eb obtained for the heat affected zone (HAZ). In general, top samples show higher breakdown potential than root samples and also the samples welded using filler metal 2209 has a better anodic behavior than the filler metal 2307. According to the results, GMAW welding process with 2209 as filler metal was revealed as the optimum chosen for application of 2304 duplex stainless steels in this case.

Jan 16, 2018

By Stephanie L. Kaster, John G. Speer, Blake M. Whitley

Niobium-microalloying technology has been increasingly applied in a wide range of steel applications over the past half-century, to increase strength, control microstructure, enhance properties and enable a variety of applications. To achieve desired performance levels, thermomechanically processed microalloyed steels are widely supplied by the steel industry for high volume applications in hot-rolled plate, sheet and structural steels. However, in steel long products and forgings, the final properties are often generated by downstream users, after heat-treatment, surface hardening, forging or wire drawing. Two examples are presented highlighting advancements associated with Nb-microalloying, to enhance microstructures and properties developed during thermomechanical and/or downstream processing. In the first example, a 0.02 wt. pct. Nb addition was made to a medium-carbon bar steel intended for induction-hardening applications requiring fatigue and fracture resistance in bending and torsion. The Nb addition as well as thermomechanical bar processing led to beneficial refinement of both the pre-induction and post-induction microstructures. In the second example, a 0.01 wt. pct. Nb addition to a high-carbon wire rod was found to refine the pearlite colony size and interlamellar spacing, and increase the hardness.

Oct 1, 2019

By Bimal Nathwani

This paper presents an overview of bearings failures with focus on steel mill applications such as continuous casting, rolling mills, multi-roll cluster mills and wire and rod mills. This paper will also provide countermeasures for prevention of these modes of failures.

Jul 30, 2018

By Diogo Tenório dos Santos

This property has been studied to characterize the strength a metallic material exhibits when it is machined so it can be regarded as its typical behaviour. As such, it may even be considered as an intrinsic material property. It is usually measured by an index called Coppini index, which is expressed by the ratio between the removed mass of a cutting tool caused by wear when it is used for machining and its initial one for a certain set of machining parameters. In this investigation, the tests were therefore conducted by an established set of parameters, namely feed rate, cutting and depth rates, in which the same wear mechanism took place in both ferrous alloys: AISI 4140 and AISI 316 steels. They were chosen based upon their increasing ordinary machinability indexes. The initial and final mass of the cutting tool were measured by an analytical scale with 0.01 mg precision. Cylindrical rods of 50-mm diameter were machined and the CI indexes showed a remarkable difference between them: 0.080 for the first steel and 0.049 for the second one, i.e., AISI 316 steel presented better machinability than the first one. It was then possible to conclude that this method presents good results in terms of both reproducibility and adequacy for machine shop conditions and it may be applied in a foreseeable future, mainly for metallic materials that have rather low machinability indices.

Jul 31, 2018

By Ramon Augusto Moretti, Henrique da Rocha Severino, Renato Nascimento de Castro, Fernando Cesar Sousa

Rolling stand 12 (LTx) of long steel, installed in the company A, Piracicaba - SP unit, had presented high levels of vibration, which affected its internal components, such as: shaft, gears and bearings, generating downtime. To evaluate this equipment a study was proposed by the following engineering techniques: Conventional Vibration Analysis, Operational Deflection Shape (ODS) and numerical simulation by the Finite Element Method (FEM). In the Conventional Vibration Analysis, high levels of vibration were observed during manufacturing process, especially when the material reaches the equipment. Impacts generate high values in acceleration, on average 80 m/s² peak to peak. In the moment of impact, misalignment of internal components was observed by ODS. Field results were correlated to those obtained by the Finite Element Method, which allowed to calibrate FEM model. Thus, the most effective structural modification already numerically evaluated was implemented in the system. Afterwards, new measurements by vibration and ODS techniques were performed, and attenuation of vibrational levels and operational mode, which overloaded the internal components rolling stand, were verified.

Oct 1, 2019

By Evan Thomas

It has been shown before that liquids can slip at a solid boundary, which prompted the idea that parallel-surface bearings can be obtained by the use of alternating slip and non-slip regions in the direction of fluid flow. The amount of slip at the wall depends upon the surface tension at the liquid - solid interface, which in turn depends on the chemical composition of the surface and its roughness. In the present study a heterogeneous surface was created by coating half of a circular glass disc with a coating repellent to glycerol. A rotating glass disc was placed at a known distance above the coated stationary surface and the gap was filled with glycerol. With the top surface moving in the direction of slip to non-slip region, a pressure build up can be theoretically predicted. The pressure gradient in the two regions is constant, similar to that in a Rayleigh step bearing, with the maximum pressure at the boundary. In order to accurately measure the force generated by the pressure increase, a load cell was attached to the heterogeneous disc. Experiments were conducted by varying both sliding speed and distance, and the resultant load carrying capacity was measured and compared with theoretical calculations. This allowed the slip coefficient of the coated surface to be evaluated.

Jul 31, 2018

By Xihuai Gong, Hongshuang Di, Jianping Li, Ning Yan

In this work, we investigated the effect of the rolling process (warm-rolled or cold-rolled) on microstructure evolution and mechanical properties of 9Mn steel. After intercritical annealing at 670°C for 10min, both cold-rolled and warm-rolled microstructures are composed of ultra-fined austenite and intercritical ferrite. The austenite in warm-rolled sample includes two types of morphology, namely equiaxed and lamellar, which exhibits a wide distribution of grain-size. The incomplete recrystallization or recovery behavior of ferrite in warm-rolled and annealed sample results in higher yield strength and shorter yield point elongation. Moreover, the warm-rolled and annealed sample extends the TRIP-related work hardening over a broad strain range, resulting in a better combination of ultimate tensile strength and total elongation.

Oct 1, 2019

By Norbert Asamer, Stefan Purrer

Depending on the product or the material grade, conventional deburring machines, such as e.g. with rotating hammers, are in many cases not capable to reliably or completely remove burrs from the edges of a continuously cast product. Burr, however, is generated at the front and/or tail ends of a slab, bloom or billet as a result from torch cutting. Likewise, traversal grinding of the slab’s rolling surfaces can also cause burr at the long side edges of the slab whereby such burr can even be more difficult to remove. Based on their experience and know-how with abrasive machining processes (abrasive cutting, high-pressure grinding) over a period of more than 50 years up to now, BRAUN has developed a highly flexible deburring grinding machine for applications which are too difficult for conventional deburring techniques. BRAUN’s deburring grinding machines were successfully introduced to the steel industry and have proven their worth under normal production conditions already. The subject paper describes the key features and advantages of BRAUN’s machine design and the operational results from the first already completed projects.

Oct 1, 2019

By Michel Rodrigo Luiz, Glaucio Augusto Polini, Giardini F. Lazzarin

ArcelorMittal's pickling and cold rolling line has been demanded to increase production since the installation of equipments in 2015. In addition to the improvement in productivity related to these new equipment, one of them the automatic surface inspection system (SIAS), work has also been developed in other equipment seeking improvement of production indicators. The present article exposes the actions and gains that were achieved with actions on two equipments in the same section as the Side Trimmer. The first one deals with the optimization of time gains with sequencing adjustments without financial contribution, using only internal labor seeking reduction of unproductive times by adjustments of the side trimmer in the cold strip mill. The second item discussed demonstrates the actions and the gains generated due to the availability of new resources (installation of SIAS equipment), the optimization of these resources seeking a focus on the reduction of ruptures in the tandem cold mill, configuring the same in the aid of the identification of critical defects and also in the automatic speed reduction action of the tandem cold mill in defects considered serious. In both cases the intention was to improve production, seeking to improve the results of the section and the line.

Oct 1, 2019

By Yong Tian, Tian Zhang, Zhao-Dong Wang

To meet the requirements of high-performance steel plates, while reducing manufacturing costs and saving energy, the advanced cooling system for plate mill (ADCOS-PM) with functions of accelerated cooling (ACC), ultra-fast cooling (UFC), and direct quenching (DQ) was researched and developed by the State Key Laboratory of Rolling and Automation (RAL). Since 2003, several sets of ADCOS-PM device were developed and implemented in industrial practice. To fully utilize the ADCOS-PM technology, the combination of various strengthening mechanisms was promoted by NG-TMCP technology and low-cost, high performance plates were produced such as pipeline steels, and high-strength construction machinery steel.

Oct 1, 2019

By Yuechang Wang

A new method of manufacturing the wavy-tilt-dam(WTD) mechanical seal has been mentioned. In this method, the special equipment is designed to provide a predetermined force to external and inner circular surface of the ring. After milling the end face of the seal by grinding miller and releasing the preload, the wavy-tilt-dam can be done on the seal surface. In this paper, a prediction model is built up to investigate the relationship between the predetermined force and the deformation on the surface of the ring by using ANSYS software. A WTD ring is manufactured by this method which approves that the prediction model is in accord with the real process and this manufacturing method of the WTD mechanical seal is a proper choice.

Jul 31, 2018

By Emanuelle Garcia Reis, Gustavo de Sousa, Rodney Pardo Alves

Gerdau Ouro Branco´s plate mill started the operation in 2016 with high level technology. In general, national and international plate markets are every day more rigorous about final product quality. Suppliers must be aware about dimensional accuracy, surface quality and flatness of the plates, independent of the quality standards. To guarantee the best service to this increasingly demanding and competitive market, it is extremely important to guarantee the original project conditions executing the right maintenance of the rolling mill main components. In order to maintain the product quality and avoid the production and maintenance cost increase, it is important to find ways to control the mill and the main process variables, through daily measurements of the equipment performance. This paper aims to present the influence of the main equipment variables that affect the mill operational stability and how to control and evaluate the mill performance.

Oct 1, 2019

By Edo Engel

Whereas only a handful of decades ago, typical blast furnace working volumes were below 1000 m³, such furnaces are currently designated compact or even mini blast furnaces. For certain business cases, however, small furnace sizes remain an attractive option. Decades ago, this size blast furnace would have produced a maximum of 0.3 Mtpa with its 600 m³ working volume over a campaign of up to four years. The current state of technology and operational know–how will allow a similarly sized furnace to produce over 0.7 Mtpa while achieving the multiple decade campaigns that have become familiar to steel producers in full sized operations. This level of productivity, but especially the reliability and supply security associated with mature technology, allows for integration into minimills or taking a first step towards a full scale BF–BOF integrated mill. Steel producers considering such scenarios, which are typically attractive for emerging economies, are confronted with fundamental decisions, one of which is for the technological basis for the compact or mini blast furnace to be included in the plant. This article addresses some of these decisions from an operations–based perspective. A small number of case studies is included.

Aug 16, 2017

By Bruno Alves Resende, Antonio Adel dos Santos

Temperature, microstructure and dimensions are the main material parameters to be controlled during hot rolling of steel. Although thermal mathematical models have long been developed and applied for hot strip rolling, each Hot Strip Mill (HSM) must have its own model adapted to its facilities. Thus, a mathematical model for temperature evolution during rough rolling has been developed for the Usiminas HSM at Ipatinga Plant. The model achieved a high level of accuracy, which was assessed by comparing measured values of temperature at the hot strip mill entry with the calculated ones, the difference ranging from 9°C to 17°C. Application examples have shown that the slab can be occasionally stopped before start of rolling for as long as a couple of minutes without compromising its further processing. On the other hand, if the transfer bar stops after rough rolling even for short time, further processing in the HSM can be hindered, due to excessive temperature drop. In case of such abnormal line stop, the model can be used as a tool for decision-making to either continuing the planned rolling schedule or to changing the route, thus improving the overall rolling process.

Oct 1, 2019

By Jean François Stumper

This paper presents the TMT “3D TopScan” profilemeter, which is a Radar-based profilemeter that measures the total burden surface within a few seconds and on a continuous basis. This equipment is based on an electronically steered solid-state radar scanner, such that a very large amount of surface data is collected within short time intervals. These new electronically steered antenna systems are the key to meet the demands for both accuracy and speed. The TMT probe is installed at a fixed location at the top cone, such that it does not interfere with the charging, enabling a continuous measurement and a compact design.Blast furnace charging optimization can be achieved based on its measurement data. The burden surface is continuously measured every few seconds, enabling the blast furnace operator to detect any details including asymmetries or irregularities in the surface pattern. A variety of process analysis tools are available. Due to the continuous and fast measurement, the burden descent speed can be supervised without process interruption on an ongoing basis. More accurate process models (layer models) than ever are obtained which fully consider the unsymmetries.This technology, developed by TMT Tapping Measuring Technology, is successfully in operation at Salzgitter Flachstahl GmbH at their blast furnace B. The probe and the data evaluation tools combine today’s technological capabilities in measurement technology with the practical requirements of blast furnace operation.

Aug 16, 2017

By Richard Harvey, Robert Paul Mawer

In recent times there has been an increase in the demand from Steel plants for a technology that offers the most economical environmentally sustainable solution. In terms of blast furnace off gas cleaning this has seen a drive towards Cyclone technology replacing the older Dustcatchers. Cyclone technology can achieve dust removal efficiencies as high as 95% increasing the dust yield at the primary stage of gas cleaning. The dry dust (rich in Fe and C) can then be recycled to the Sinter Plant or Blast Furnace. Capture of dust at this stage also has the benefit that sludge generation from the secondary stage is also reduced meaning less waste to landfill and / or recovery of some of the by-products for further use. Primetals Technologies already offer a state of the art Tri-Axial Cyclone installed on many sites world-wide, however, this paper focuses on a hybrid of this technology, the DustClone. The DustClone is a low CAPEX unit that is essentially a Cyclone housed inside the Dustcatcher. This unit is aimed at operators who may be carrying out smaller scaled shutdowns / repairs that normally have a reduced CAPEX. This paper describes the technology that Primetals Technologies have developed.

Oct 1, 2019

By Christian Geerkens

Increasing requirements on slab quality initiates SMS group in developing products with a high sophisticated level regarding production and process. These characteristics are represented by SMS group’s HD family. HD stands for High Definition or the improvement of product quality via higher precision of the casting processes. A deep look inside into casting process is realized by the use of fiber optical equipped HD mold. High definition casting process control is assured using the HD spray and HD size. For objective, environmentally friendly and highly informative analyze of the inner quality of the cast products the new HD scan is present.

Aug 16, 2017

By Douglas Glenn Stalheim

The uniformity of the final cross sectional microstructure and subsequent final mechanical properties and shape of structural steels is dependent on the type or types of recrystallization behaviors that are created. There are three main recrystallization behaviors that are the foundation of the metallurgy created during production. Alloy design and subsequent processing design strategy drive how much of each recrystallization behavior is created through the cross section of the product. Carbon manganese steels create only one basic behavior while the addition of microalloys, in particular niobium, can add two additional behaviors. The behaviors are intertwined with each other and build upon each other. The three behaviors are Type I, static recrystallization, Type II, no-recrystallization, and Type III, metadynamic/dynamic recrystallization. How much of each behavior is generated through the cross section through the production influences the final transformed microstructure and corresponding mechanical properties and shape performance. This paper will discuss the three behaviors, how they are generated, how to identify which behavior is occurring through modeling or actual mill data. Actual examples from production will be discussed.

Aug 16, 2017