This paper presents a model of the magnetostrictive hysteresis loop with local maximum. The model is based on the differential equations describing magnetostriction due to the domain wall movement as ...well as domain magnetization rotation. The transition between these mechanisms of magnetization is quantified by the Maxwell⁻Boltzmann distribution. Moreover, the lift-off phenomenon in the magnetostrictive hysteresis loop is considered. The proposed model was validated on the results of measurements of magnetostrictive hysteresis loops of Mn
Zn
Fe
O₄ ferrite for power application and 13CrMo4-5 construction steel. The results of modeling confirm that the proposed model corresponds well with experimental results. Good agreement was confirmed by determination coefficient R², which exceeded 0.995 and 0.985 for Mn
Zn
Fe
O₄ ferrite for power application and 13CrMo4-5 construction steel, respectively.
In this paper, we estimate the fire resistance of rolled products from construction steels based on the results of thermomechanical tensile tests of laboratory specimens at elevated temperatures. For ...the study, 05GNDB, 10G2FBYu, 10KhSND, 09G2S, and 06MBF steels and samples in the form of industrial rolled products of strength categories S345–S375 were selected. Tensile at elevated temperatures were tested in accordance with GOST 9651–84. Based on the test results, critical fire resistance coefficient YS
c
, which was calculated as the ratio of the conditional yield strength determined at a critical temperature of 600°C to its value at 20°C, was determined.
The thermo-mechanical control processing (TMCP) of low carbon (C) Nb-Ti-containing HSLA steel with different cooling rates from 5 to 20 °C/s was simulated using a Gleeble 3500 system. The samples’ ...microstructure was characterized and the tensile properties measured. The results show that a microstructure mainly consisting of quasi-polygonal ferrite (QPF), granular bainitic ferrite (GBF), and martensite/austenite (M/A) constituent formed in each sample. Furthermore, the accelerated cooling led to a significant grain refinement of the QPF and GBF, and an increase in the density of dislocations, as well as suppressed the precipitation of nanoscale particles; however, the overall yield strength (YS) still increased obviously. The accelerated cooling also brought about a decrease in amount of M/A constituent acting as a mixed hard phase, which weakened the overall strain-hardening capacity of the QPF + GBF + M/A multiphase steel and simultaneously elevated yield-to-tensile strength ratio (YR). In addition, the mechanisms in dominating the influence of controlled cooling on the final microstructure and tensile properties were discussed.
The Research of Carbon Construction Steel at Laser Alloying Smirnova, sZhanna. V.; Rudenko, Alexander A.; Vaganova, Olga I. ...
International journal of innovative technology and exploring engineering,
07/2019, Volume:
8, Issue:
9
Journal Article
Open access
Relevance: The theme of machine components case-hardening when heated by a laser ray has been and remains currently relevant. Laser case-hardening is characterized by a number of exclusive ...advantages: hardening of hard-to-reach surfaces, ensuring local hardening, including “spot” one when a continuous layer of fragile material vulnerable to cracking and destruction doesn’t form; the lack of deformations and warping of processed parts as well as finishing operations; getting desired properties both mechanical and chemical ones by introducing different elements in the uppermost layer of a product at its melting by a laser ray, i.e. at implementing laser alloying.
In a steel plant, one of the critical tasks of plant logistics is the transportation of the finished products. A steel company transportation system generally consists of a fleet of load-carrying ...trailers and rail, which are used to transport finished goods. In this paper, a two-stage mathematical model is developed for an Indian company that helps with strategic planning of the supply of finished construction steel (TMT Bar and Structural Steel) from multiple plant locations to the stockyards and then to the distributors. The transportation cost depends on various factors like the type of transportation mode, loading & unloading charges, and other fixed expenses. The steel demand also varies based on the season and other external factors like COVID-19, government policies, and so forth. The model proposed in the present research facilitates cost-effective network planning by achieving the most appropriate dispatching method considering various factors operating in multiple stages using a mixed fleet of trailers and rail. The model’s key objective is to optimize the transportation cost and demand for construction steel.
Volumetric steel structures are commonly used in the construction of modular buildings to overcome environmental hazards, control wastage, minimise construction safety issues, improve productivity ...and cost-effectiveness, reduce labour, and execute quick project completion. An adequate structural design and effective manufacturing are both integral processes to produce efficient and durable volumetric steel structures. Design for Manufacture and Assembly (DfMA) principles known for efficient design in the automobile industry can significantly improve the design of volumetric steel structures in terms of overall cost, safety, sustainability, productivity and time. The current research presents a case study of a volumetric steel structure in which structural design and DfMA approaches were integrated, and 3D visualisation was achieved by Building Information Model (BIM) and Solidworks that has limited previous research. The findings of this research reveal sustainable, material and cost optimised design for the prefabricated 3D steel structures. Furthermore, the novelty of the current research is enhanced by proposing a model for the automated efficient design and production of volumetric steel structures.
The purpose of the study is an experimental determination of the stress-related characteristics of the structural steel produced in the Republic of Kazakhstan for use in conventional and ...earthquake-resistive construction. Since 2015, the construction industry has been using European regulatory documents—Eurocodes—as a statutory framework. In particular, the Eurocode 1993 for steel structures and the Eurocode 1998 for the design of earthquake-resistant structures However, the study of stress-related properties of structural steel using experimental methods of ISO standards has not been performed. Therefore, in the construction industry of the Republic of Kazakhstan, steel-work structures have been used in fairly limited volume since 2015. The experimental studies were conducted on 7 types of structural steel with thicknesses of 8, 10, and 20 mm manufactured by Arcelor Mittal. The yield strength, ultimate tensile strength (breaking stress), and tensile strength at break were studied. The experimental studies were carried out on the basis of ISO standards. In each test run, 5 samples were used. In two series, 20 samples each were tested, which made it possible to estimate the yield strength and strength distribution functions. The correlation relationships between Brinell hardness and yield and strength limits have been studied. As a result of experimental studies, it was found that the strength and deformability parameters fully comply with the requirements of Eurocode 1993. Based on the application of the Student's test, it is revealed that the distribution functions of yield strength and resistance correspond to the normal law (Gaussian function). The calculation of a three-story, two-span residential building with box section columns for construction in an area with a seismicity of 8 points is performed by the finite element method. The work results will significantly increase the scope of Kazakhstani structural steel use in seismic and conventional areas of the Republic of Kazakhstan. Doi: 10.28991/CEJ-2024-010-03-09 Full Text: PDF
Influences of cooling time (welding heat input) on microstructure, impact toughness and the fracture mechanism of the weakest CGHAZ (coarse-grained heat-affected zone) in a novel high-strength ...low-carbon microalloyed construction steel were studied for the purpose of laying a theoretical foundation for developing welding support technologies. When the cooling time (t
8/5
) was increased, the microstructure changed from dot shape M-A constituents and lath martensite/bainite to slender and blocky M-A constituents and coarse granular bainite. Accordingly, the impact toughness deteriorated. Large blocky M-A constituents seriously reduced the impact absorbed energy during crack initiation. For coarse bainite, the high-misorientation boundary almost disappeared. Therefore, crack initiation energy determines the cleavage fracture micromechanism of high heat input construction steel.
In this article, thermomechanical controlled processing (TMCP) plus tempering (T) is adopted to acquire a novel 690 MPa‐grade high‐strength low‐carbon bainitic construction structural steel, which ...has an optimum balance of strength‐ductility and lower yield ratio (YR). The results show that the as‐rolled steel consists of bainitic ferrite, lath‐like bainite, and granular bainite. With an increase in the tempering temperature, a great deal of carbonitrides precipitates and maintains a small nano‐scaled size without coarsening. Their interaction with dislocations induces an increase in strength. When the tempering temperature further increases, some grain boundaries between adjacent bainitic laths gradually blur or even disappear, and the average width of the bainitic laths increases to ≈860 nm. The recovery of bainitic laths is the main reason for the decreased strength. Due to the synergistic effect of the small dot‐shaped martensite/austenite (M/A) constituents and grain boundaries misorientation distribution, maximum impact absorbed energy is achieved after tempered at 500 °C. Furthermore, the lower YR is achieved by appropriate control of strength difference between the soft bainitic ferrite and hard M/A constituents via tempering.
Thermomechanical controlled processing (TMCP) plus tempering is adopted to acquire a novel 690 MPa‐grade construction structural steel with high‐strength toughness, superior weldability, resistance to fire, anti‐seismic, and anti‐corrosion. The strengthening and toughening mechanisms are discussed in detail, and the optimum lower yield ratio can be obtained by broadening the strength difference between soft bainitic ferrite and hard martensite/austenite (M/A) constituents.
Abstract
To meet the engineering demand for vibration control of a super-tall integral jacking platform moulding system, a tuned liquid damper (TLD) is used for the tuned control device of the ...construction steel platform. An experimental method for isolating the substructure is proposed, and the effectiveness of the TLD for vibration damping control of the steel platform is verified by shaking table tests. The test results show that the dynamic response of the construction steel platform and the main body of the structure under earthquake can be suppressed simultaneously by controlling the mass ratio of TLD to the construction platform within 5%, and the displacement damping effect is good.
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