 Subjects -> METALLURGY (Total: 58 journals)
|
|
|
- Monitoring the Blast furnace working state by a combination of innovative
measurement techniques
Authors: Tatjana Mirkovic, Hauke Bartusch, Pavel Ivashechkin, Thorsten Hauck
Pages: 411 - 423
Abstract: At blast furnace B at Salzgitter Flachstahl a series of innovative measuring techniques are installed to monitor the processes at the blast furnace top, making this furnace one of the best equipped furnaces in Europe. These techniques comprise full 2D measurement of the temperature profile of the top gas shortly above the burden surface, 3D radar scan of the whole burden surface and online measurement of the dust concentration in the top gas. After more than 5 years’ experience with most of these techniques, they enable to better understand the complex chemical and physical interrelations occurring in the BF stack between the ascending process gas and the descending solid burden. A couple of examples of incidents that were monitored are presented in this article, including influences of charging programmes on top gas temperature profiles and influences of disturbed gas solids interaction on the BF working state. The new measuring techniques with tailor-made data processing enable the operators to gain a better picture of the processes currently occurring in the blast furnace, consequently supporting them in keeping the blast furnace operation as stable and efficient as possible.
PubDate: 2021-12-21
DOI: 10.30544/757
Issue No: Vol. 27, No. 4 (2021)
- Estimation of phosphorus distribution ratio at the end of blowing in BOF
Authors: Z. M. Slović, D. Bradarić, Karlo Raić, J. Z. Slović
Pages: 425 - 436
Abstract: In integrated steel plants, the removal of phosphorous normally takes place during the primary basic oxygen furnace (BOF) steelmaking process. Phosphorous is usually introduced to the integrated steelmaking process through blast furnace additions, such as iron ore, coke, sinter, and fluxes. Among the others parameters such as optimizing the charging system, oxygen supply system, oxygen lance parameters of the converter, the flux quality in combination with temperature process control can improve the BOF efficiency of Dephosphorization. Phosphorus partition ratio (LP) is usually used to evaluate the thermodynamic efficiency of the dephosphorization of slags with different compositions in steelmaking processes. However, this parameter is only useful in equilibrium conditions, and it is not accurate when used to evaluate slag efficiency in industrial processes. Because of this, the aim of this work was to study the phosphorus partition ratio estimated from the experimental results in real plant conditions of two different BOF steel plants and compare them with well-known published models. In the present study, data from two steel plants (further Plant A and Plant B) were evaluated applying Healy’s, Suito and Inoui’s, Zhang’s as well as Assis’s equations. The calculated values were compared against measured values.
PubDate: 2021-12-21
DOI: 10.30544/646
Issue No: Vol. 27, No. 4 (2021)
- Algorithm for quantifying the particle size distribution of non-metallic
inclusions formation in steel production
Authors: Marija Mihailović, Karlo Raić
Pages: 437 - 447
Abstract: When the quantitative characterization of non-metallic inclusions in steel is done and the effect of limiting factors is assessed, and based on that the possibility of reconstruction of the total content of non-metallic inclusions in steel is estimated, further considerations can be directed towards predicting the model of size distribution curve. The aim of this work is to establish relations on the basis of which it will be possible to quantify the content of non-metallic inclusions in extra-pure steels, when metallographic control is difficult or even impossible by routine procedures.
PubDate: 2021-12-25
DOI: 10.30544/776
Issue No: Vol. 27, No. 4 (2021)
- Static-dynamic model for endpoint control used in Smederevo's BOF
shop
Authors: Tomislav D Bradarić, Z. M. Slović, G. J. Stepanoski, S. Kosanović
Pages: 449 - 456
Abstract: This paper describes the computer model for BOF control that was in use at Smederevo, Serbia, during the period 1994-2006. The model was developed at the Institute of Metallurgy of the Smederevo Steelwork in mid-1994 and was motivated by the fact that the plant in Smederevo, by that time, had many years of experience in endpoint control using Intermediate Stop Practice (ISP). The vision for the model was to continuously improve and adapt to the working conditions of production through self-learning and adjustments. The model belongs to the well-known family of Static-Dynamic models (SDMs). It is aimed to reduce the "oxygen off-to-start tap" time and thus increase productivity and reduce production costs. The paper briefly describes the metallurgical software, operator operations and provides some information on the model's effectiveness.
PubDate: 2021-12-28
DOI: 10.30544/716
Issue No: Vol. 27, No. 4 (2021)
- Application of thermal analysis in ferrous and nonferrous foundries
Authors: Mile B Djurdjevic
Pages: 457 - 471
Abstract: This paper is devoted to the memory of Professor Ljubomir Nedeljkovic (1933-2020), Head of the Department of Iron and Steel Metallurgy University of Belgrade, Serbia. Assessment of the melt quality is one of the most important casting process parameters, which allowed sound production of intricated cast parts. At the present time, various devices have been applied at foundry floors to control melt quality. Thermal analysis is one of them, widely used for melt quality control in ferrous and non-ferrous casting plants. During solidification, metal and alloys released latent heat, which magnitude is dependent on the type of phases that form during the solidification process. Plotting temperature versus time data during solidification provides useful information related to the actual solidification process. The applied technique is called thermal analysis, whereas the cooling curve is the name of such a plot. The main aim of this paper is to give a short overview of the present thermal analysis application in various foundries and to indicate the future potential use of this technique.
PubDate: 2021-12-21
DOI: 10.30544/673
Issue No: Vol. 27, No. 4 (2021)
- Some advanced welding technologies applied for repair welding in power
plants
Authors: Zoran Dušan Odanović
Pages: 473 - 487
Abstract: Steels are subjected to many time-dependent degradation mechanisms when they are applied in electric power plants. They are exposed to high temperatures, multi-axial stresses, creep, fatigue, corrosion, and abrasion during such services. Used under these threatening conditions, those materials could develop various damages or failures or even form cracks. Therefore, it is desirable to prevent in-service failures, improve reliability, and extend the plant's operational life. The efficiency of the electric power plant, among other processes, depends on effective maintenance. The paper presents the evaluation of advanced procedures and knowledge in the field of steel repair welding in the maintenance of the power plants. Most repair welding of low alloy steels requires high-temperature post-weld heat treatment (PWHT), but in certain repairs, however, this is not always possible. Application of the nickel-based filler metal could also be an alternative to performing post-weld heat treatment (PWHT). The repair work expenses could be reduced if the repair is performed on-site. The novel developed repair welding procedures presented in this paper were applied for emergency weld repairing of the steel pipelines in thermal power plant, repairing without disassembling the working wheel of the coal mill in thermal power plant and "on-site" repairing turbine shaft of the hydropower plant. For all the presented repair welding procedures, weldability analysis based on the analytical equations and technological ''CTS'' and ''Y'' tests to determine the sensitivity to cold and hot crack forming were applied. Tensile tests, absorbed energies tests, banding tests, and hardness measurements were performed on trial joints, which were used to develop and verify the applied methodologies. Presented advanced weld repair technologies enable repairs for a shorter time and at lower costs compared to conventional procedures.
PubDate: 2021-12-21
DOI: 10.30544/631
Issue No: Vol. 27, No. 4 (2021)
- Microstructural characterization and mechanical performance along the
thickness of electron beam welded stabilized AISI 321 stainless steel
Authors: Ajay Sharma, Vineet Prabhakar, Sandeep Singh Sandhu
Pages: 489 - 504
Abstract: The Electron Beam welding (EBW) process was employed to fabricate 18 mm thick fully penetrated butt welds of AISI 321 stainless steel. Nail shaped weld wide at the top and narrow at the bottom was obtained. Characterization of the weld joint was carried out using optical microscopy, scan electron microscopy, X-ray diffraction, microhardness, impact toughness test and tensile strength test. The microstructure of the weld metal was found to be free from defects like cracks porosity etc. The weld metal consisted of the primarily austenitic matrix with skeletal and vermicular morphology of δ-ferrite by the side of the grain boundaries. Carbides of Cr and Ti were found in the weld metal after the thermal aging treatment of 750°C for 24 hours as reveled by the XRD analysis. The tensile strength study revealed a maximum strength of 575 MPa at the root of the weld joint in the as-welded state. The maximum impact toughness of 129.3 J was obtained in the top section of the weld in the as-welded condition. The results in terms of structure-property correlaterelationship. This study recommends the effectiveness of EBW for joining 18 mm thick AISI 321.
PubDate: 2021-05-17
DOI: 10.30544/592
Issue No: Vol. 27, No. 4 (2021)
- Pulse spray gas metal arc welding of advanced high strength S650MC
automotive steel
Authors: Ashok Kumar Srivastava, Pradip K Patra
Pages: 505 - 517
Abstract: With an increasing demand for safer and greener vehicles, mild steel and high strength steel are being replaced by much stronger advanced high strength steels of thinner gauges. However, the welding process of advanced high strength steels is not developed at the same pace. The performance of these welded automotive structural components depends largely on the external and internal quality of weldment. Gas metal arc welding (GMAW) is one of the most common methods used in the automotive industry to join car body parts of dissimilar high strength steels. It is also recognized for its versatility and speed. In this work, after a review of GMAW process and issues in welding of advanced high strength steels, a welding experiment is carried out with varying heat input by using spray and pulse-spray transfer GMAW method with filler wires of three different strength levels. The experiment results, including macro-microstructure, mechanical properties, and microhardness of weld samples, are investigated in detail. Very good weldability of S650MC is demonstrated through the weld joint efficiency > 90%; no crack in bending of weld joints, or fracture of tensile test sample within weld joint or heat affected zone (HAZ), or softening of the HAZ. Pulse spray is superior because of thinner HAZ width and finer microstructure on account of lower heat input. The impact of filler wire strength on weldability is insignificant. However, high strength filler wire (ER100SG) may be chosen as per standard welding practice of matching strength.
PubDate: 2021-12-21
DOI: 10.30544/682
Issue No: Vol. 27, No. 4 (2021)
- Corrosion rate and corrosion behaviour analysis of carbon steel pipe at
constant condensed fluid
Authors: Ahmad Royani, Siska Prifiharni, Gadang Priyotomo, Sundjono Sundjono
Pages: 519 - 530
Abstract: This study investigates the corrosion rate and corrosion behavior of carbon steel pipe at constant condensed fluid from a geothermal power plant. The corrosion rate of the steel was determined by weight loss analysis, whereas the corrosivity of the condensate fluids was measured by a multimeter Hach HQ40d. The morphology of the corrosion products formed was characterized by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and x-ray diffraction (XRD) analysis. Results showed that the corrosion rate in the liquid part of the condensate fluids is constant during the immersion period when water quality parameters are constant. Meanwhile, the corrosion rate of low carbon steel pipe decreases though with the longer exposure period in the condensate fluid. The decrease of metal corrodibility identical to the lower corrosion rate at a longer exposure time due to the protective corrosion layer formed. The corrosion products during immersion tests identified in the corrosion test were uniform with iron oxide in the form of FeO(OH) and Fe2O3*H2O.
PubDate: 2021-04-29
DOI: 10.30544/591
Issue No: Vol. 27, No. 4 (2021)
- Effects of temperature and load during hot impression behavior of Cr-Ni
stainless steel
Authors: P. Bharath Sreevatsava, E. Vara Prasad, A. Sai Deepak Kumar, Mohammad Fayaz Anwar, Vadapally Rama Rao, Vanitha Chilamban
Pages: 531 - 539
Abstract: Austenitic Stainless steels are majorly used because of their high resistance to aqueous corrosion and high temperature properties. Some major applications of stainless steels at high temperatures include engine and exhaust components in aircrafts, recuperators in steel mills, and pulverized coal injection lances for blast furnaces. In all the above said applications, the components are constantly subjected to loads and high temperatures. This makes the study of their creep behavior very important to decide the life of the component. Cr-Ni stainless steel was used as a starting material, and hot impression creep test was performed on cylindrical samples of 10 mm height and 15 mm diameter for a dwell time of 150 min at two different loads of 84 and 98 MPa and at two different temperatures 450 and 500 °C. The time vs. indentation depth was plotted, and creep rate was calculated in each case. It was observed that with an increase in time, creep rate increased in the primary creep region and remained almost constant in the secondary creep region irrespective of temperature and load. The indentation depth and creep rate increased with an increase in load and temperature.
PubDate: 2021-12-28
DOI: 10.30544/745
Issue No: Vol. 27, No. 4 (2021)
- Effect of heat treatment on hardness and wear resistance of high
carbon-high chromium steel (FMU-11)
Authors: Alireza Darvishi, Aria Daneshmayeh, Alihosein Salehi, Mahdi Ahmadi, Alireza Soleymani
Pages: 541 - 556
Abstract: In the present study, microstructure, hardness, and abrasion resistance of a heat-treated high carbon-high chromium steel (FMU-11) used in the cement mills were investigated. To investigate the best heat-treating cycle for the FMU-11 steel, three sets of samples were heat treated. The first set was tempered two times, the second set was re-hardened, and the third set was cryogenically heat treated. These samples were then compared with the conventionally heat-treated samples. The samples' microstructure was studied using an optical microscope, where traditional black and white etching, as well as color etching, were used. Scanning electron microscopy (SEM) was applied for higher magnification studies and in-depth analysis of the chemical composition. The mechanical properties were investigated by measuring the hardness and the wear resistance for the samples heat-treated in different cycles. The results showed that the cryogenic treatment and double-tempered samples had the highest hardness and wear resistance. In addition, the results showed that the re-hardening operation caused the carbides to be finely separated and evenly distributed in the steel matrix. The wear test results illustrated that the wear mechanism could be the delamination wear and the abrasive wear combined.
PubDate: 2021-01-27
DOI: 10.30544/596
Issue No: Vol. 27, No. 4 (2021)
- Effect of SEN immersion depth on mold flow profile and slag entrapment
during continuous casting of steel
Authors: Mallikarjuna Rao P, Vaibhav Vasantrao Chougale, Satish Kumar D, Rajendra T, Balachandran G
Pages: 557 - 573
Abstract: Mold flux entrapment during continuous casting of steel contributes to both surface and sub-surface defects in the final product. Continuous casting operating parameters such as casting speed, SEN immersion depth, SEN port geometry, argon flow, and mold EMS significantly affect the mold flow conditions and flow profile. During continuous casting operation, SEN immersion depth is continuously varied to avoid localized erosion of SEN, and it impacts the flow dynamics in the mold. In the present work, water modeling studies were carried out for a wide range of mold widths (1200-1800 mm) and casting speeds (0.8-1.4 m/min) on a 0.5 scaled down water model to optimize casting speed for different combinations of SEN immersion depth and mold width. Results from water modeling were further validated using nail board studies in the actual plant. A safe operating matrix was identified from these experiments to avoid mold slag entrapment during continuous casting.
PubDate: 2021-10-05
DOI: 10.30544/653
Issue No: Vol. 27, No. 4 (2021)
|
Open Access journal
