scholarly journals ABOUT TECHNOLOGICAL FEATURES OF PRODUCTION OF REINFORSING BARS FROM PEARLITE GRADE STEELS

2021 ◽  
pp. 55-64
Author(s):  
E.V. PARUSOV ◽  
S.I. GUBENKO ◽  
І. М. CHUIKO ◽  
O.V. PARUSOV
Keyword(s):  
Carbon Content ◽  
Strength Class ◽  
High Strength ◽  
Carbon Steels ◽  
International Standards ◽  
Reinforcing Bars ◽  
High Carbon ◽  
Reinforcing Bar ◽  
The Usa ◽  
The Uk

Formulation of the problem. In the production of coiled rolled products from perlite grade steels, metallurgical enterprises encounter with the sorting of some batches of continuously cast billets or commercial products due to non-compliance with regulatory requirements. One of the alternative ways of using such blanks can be their reassignment for the production of thermally hardened reinforcing bars. In accordance with the edition of GOST 5781-82, it was possible to produce hot rolled reinforcing bars from steel grade 80C (carbon content 0,74…0,82 %), and according to TU 14-15-339-94 – thermally hardened with a carbon content of 0,50…0,85 % C. In world practice, reinforcing bars of a strength class similar to classes A800…A1000 (DSTU 3760:2019) are made mainly of high-carbon steels. The main type of stressed reinforcement in the EU, USA, Canada and Great Britain are rods with a nominal diameter of 26…40 mm of strength class 835…1030 MPa and 26…36 mm of strength class 1080…1230 MPa. An analysis of the requirements for reinforcing bars according to various regulatory documents shows that in the standards of Canada, the USA and the UK, the carbon content is not standardized, but according to the standards of Japan and Ukraine it is 0,45…0,80 % and 0,13…0,37 % respectively. According to the requirements of international standards, the minimum values of the yield strength and strength correspond to the reinforcing bar A800 (DSTU 3760:2019). Therefore, for the possibility of producing reinforcing bars from high-carbon steels, it is necessary to establish rational temperature-time conditions for heat hardening modes, which will ensure that the finished metal products comply with the requirements of DSTU 3760:2019. Purpose. Determine the influence of the parameters of the technology of thermal hardening on the features of the formation of the structure and mechanical properties of reinforcing bars made of steels with a carbon content of 0,50…0,90 %. Results. The possibility of producing reinforcing bars of strength classes А800 and А1000 from steels С56DВ, C70DВ, C80DВ and C82DВ (EN 16120-2:2017) using intermittent and interrupted quenching methods has been scientifically proven. In accordance with the results obtained, the industrial production of reinforcing bars of strength classes A800 and A1000 from these steels is expedient, since it will contribute to the improvement of technical and economic indicators in the production of coiled steel from perlite grade steels intended for high-strength products (cold-worked rebar, metal cord, bead wire, spring wire, reinforcing ropes, etc.). Based on the results of industrial experiments, a technical agreement was developed and approved for the production of pilot batches of thermally hardened reinforcing bars of strength classes A800 and A1000 from steels containing 0.50...0.90 % carbon.

scholarly journals Trends in educational mobility: How does China compare to Europe and the United States?

2019 ◽  
Vol 5 (2) ◽  
pp. 214-240
Author(s):  
Rob J Gruijters ◽  
Tak Wing Chan ◽  
John Ermisch
Keyword(s):  
Educational Opportunity ◽  
The United States ◽  
International Standards ◽  
Educational Mobility ◽  
The Us ◽  
The Usa ◽  
Economic Boom ◽  
The Uk ◽  
Large Decline ◽  
Inequality Of Educational Opportunity

Despite an impressive rise in school enrolment rates over the past few decades, there are concerns about growing inequality of educational opportunity in China. In this article, we examine the level and trend of educational mobility in China, and compare them to the situation in Germany, the Netherlands, the UK and the USA. Educational mobility is defined as the association between parents’ and children’s educational attainment. We show that China’s economic boom has been accompanied by a large decline in relative educational mobility chances, as measured by odds ratios. To elaborate, relative rates of educational mobility in China were, by international standards, quite high for those who grew up under state socialism. For the most recent cohorts, however, educational mobility rates have dropped to levels that are comparable to those of European countries, although they are still higher than the US level.

scholarly journals Study on the Bending and Joint Performances of Reinforced Concrete Beams Using High-Strength Rebars

2021 ◽  
Vol 13 (6) ◽  
pp. 3482
Author(s):  
Seoungho Cho ◽  
Myungkwan Lim ◽  
Changhee Lee
Keyword(s):  
Yield Strength ◽  
High Strength ◽  
Reinforced Concrete Beams ◽  
High Yield ◽  
Performance Tests ◽  
Reinforcing Bars ◽  
Joint Performance ◽  
Lap Splice ◽  
Reinforcing Bar ◽  
Nominal Strength

High-strength reinforcing bars have high yield strengths. It is possible to reduce the number of reinforcing bars placed in a building. Accordingly, as the amount of reinforcement decreases, the spacing of reinforcing bars increases, workability improves, and the construction period shortens. To evaluate the structural performance of high-strength reinforcing bars and the joint performance of high-strength threaded reinforcing bars, flexural performance tests were performed in this study on 12 beam members with the compressive strength of concrete, the yield strength of the tensile reinforcing bars, and the tensile reinforcing bar ratio as variables. The yield strengths of the tensile reinforcement and joint methods were used as variables, and joint performance tests were performed for six beam members. Based on this study, the foundation for using high-strength reinforcing bars with a design standard yield strength equal to 600 MPa was established. Accordingly, mechanical joints of high-strength threaded reinforcing bars (600 and 670 MPa) can be used. All six specimens were destroyed under more than the expected nominal strength. Lap splice caused brittle fractures because it was not reinforced in stirrup. Increases of 21% to 47% in the loads of specimens using a coupler and a lock nut were observed. Shape yield represents destruction—a section must ensure sufficient ductility after yielding. Therefore, a coupler and lock nut are effective.

scholarly journals Development of a structure of norms for steel products based on a principle of advanced standardization

2019 ◽  
Vol 17 (1) ◽  
pp. 86-93
Author(s):  
Sergey V. Snimshchikov ◽  
Marina A. Polyakova ◽  
Aleksandr S. Limarev ◽  
Veniamin A. Kharitonov
Keyword(s):  
Product Quality ◽  
International Norms ◽  
International Standards ◽  
National Standards ◽  
Reinforcing Bars ◽  
Reinforcing Bar ◽  
Analysis And Synthesis ◽  
Standard Structure ◽  
National Practice ◽  
Quality Indexes

Problem Statement (Relevance): It is shown in the paper that at present one of the important problems in standardization is to harmonize requirements in standards with international norms. It is caused by the necessity to increase the product competitiveness in the external market conditions. At the same time, national practice in standardization, a variety of valid standards on the same product as well as the existing structure of standards do not make it possible to fully harmonize product quality indexes which are normalized in national standards with the relevant indexes of the best world similar standards. Objectives: Development of a new concept for a standard structure which allows combining requirements of both valid national standards and international norms. Methods Applied: When developing a new concept for the standard structure, the authors used universal methods of scientific cognition: analysis and synthesis, deduction, analogy, extrapolation, abstraction. Originality: Novelty of the proposed approach is based on the development of a new procedure for creating standards taking into consideration the existing practice in the product quality indexes setting, the level of similar world quality indexes, and economical factors. Findings: The paper presents the application of the developed concept for a standard structure by the example of an interstate standard for reinforcing bars. It was shown that a basic difference in the standard structure is that the standard had two sections. The first section contains norms valid in revoked national standards. The second section includes the requirements which were harmonized with the international standards. This makes it possible for a manufacturer to choose independently such kind of a technological process for reinforcing bar production which fully corresponds with the existing process facilities. Practical Relevance: The proposed concept for arrangement of the standard structure makes it possible to take into consideration the existing national experience in the area of setting norms for product quality indexes which are to the maximum extent harmonized with the level of similar world properties.

scholarly journals Influence of Carbon Content and Carbide Distribution on Recrystallization in Cold Rolled High Carbon Steels

1991 ◽  
Vol 77 (12) ◽  
pp. 2147-2154 ◽  
Author(s):  
Kiyoshi FUKUI ◽  
Teruo KANEKO ◽  
Atsuki OKAMOTO
Keyword(s):  
Carbon Content ◽  
Carbon Steels ◽  
High Carbon ◽  
Carbide Distribution ◽  
Cold Rolled

scholarly journals The c/a Ratio in Quenched Fe-C and Fe-N Steels - A Heuristic Story

2007 ◽  
Vol 539-543 ◽  
pp. 215-222 ◽  
Author(s):  
Oleg D. Sherby ◽  
Jeffrey Wadsworth ◽  
D.R. Lesuer ◽  
C.K. Syn
Keyword(s):  
Carbon Content ◽  
Abrupt Change ◽  
Transformation Process ◽  
Carbon Steels ◽  
The Body ◽  
Low Carbon ◽  
High Carbon ◽  
Linear Change ◽  
Bcc Structure ◽  
Fcc Structure

The body-centered tetragonal (BCT) structure in quenched Fe-C steels is usually illustrated to show a linear change in the c and a axes with an increase in carbon content from 0 to 1.4%C. The work of Campbell and Fink, however, shows that this continuous linear relationship is not correct. Rather, it was shown that the body-centered-cubic (BCC) structure is the stable structure from 0 to 0.6 wt%C with the c/a ratio equal to unity. An abrupt change in the c/a ratio to 1.02 occurs at 0.6 wt%C. The BCT structure forms, and the c/a ratio increases with further increase in carbon content. An identical observation is noted in quenched Fe-N steels. This discontinuity is explained by a change in the transformation process. It is proposed that a two-step transformation process occurs in the low carbon region, with the FCC first transforming to HCP and then from HCP to BCC. In the high carbon region, the FCC structure transforms to the BCT structure. The results are explained with the Engel-Brewer theory of valence and crystal structure of the elements. An understanding of the strength of quenched iron-carbon steels plays a key role in the proposed explanation of the c/a anomaly based on interstitial solutes and precipitates.

Quality Control Framework for Statutory Audit of Financial Statements: A Comparative Study of USA, UK and India

2016 ◽  
Vol 9 (2) ◽  
pp. 186-211 ◽  
Author(s):  
Siddhartha Sankar Saha ◽  
Mitrendu Narayan Roy
Keyword(s):  
Quality Control ◽  
The United States ◽  
International Standards ◽  
Control Policies ◽  
Accounting Firms ◽  
Quality Control Standard ◽  
Policies And Procedures ◽  
Control Framework ◽  
The Usa ◽  
The Uk

Quality control of audit procedure has become extremely important in today’s corporate environment in the backdrop of accounting irregularities and audit failures leading to corporate demise. Accounting firms control the quality of audit procedure with the help of the quality control standard (QCS) and specific auditing standard. These standards provide reasonable assurance of compliance with applicable regulation and issuance of the appropriate report by the engagement team. After discussing the international scenario of quality control framework, in this study a comparative analysis of quality control policies and procedures at firm and engagement in three select countries has been presented. The countries selected are the United States of America (USA), the United Kingdom (UK) and India. The study finds that the QCS and the auditing standard in all three countries are designed in line with International Standards on Auditing (ISAs) and International Standards on Quality Control (ISQC)-1. Naturally, quality control policies and procedures in three countries are comparable barring few minor differences. Based on these differences, it can be concluded that the quality control framework in the UK and India is more stringent as compared to the USA.

Transparency in the German real estate market

2005 ◽  
Vol 23 (1) ◽  
pp. 90-108 ◽  
Author(s):  
Karl‐Werner Schulte ◽  
Nico Rottke ◽  
Christoph Pitschke
Keyword(s):  
Real Estate ◽  
Real Estate Market ◽  
International Standards ◽  
Real Estate Industry ◽  
Content Type ◽  
Real Estate Markets ◽  
Current State ◽  
The Usa ◽  
Private And Public ◽  
The Uk

PurposeGerman real estate markets used to show little transparency in the past. This has changed over the last 15 years. The purpose of this study therefore is to examine the current state of transparency.Design/methodology/approachThe study investigates and discusses the concept of transparency in general, availability of private and public market data, major real estate investment products, performance measurement, changes in the regulatory environment and the emergence of organizations and publications. The findings of this study are obtained in a comparative manner: The transparency status of the 1990s in the different areas researched is compared to the current German and other international standards. The authors describe the relatively opaque German real estate market as it was at the beginning of the 1990s and show how it has improved to date.FindingsThe results show that transparency in the German real estate market has noticeably improved in all researched areas. But still, compared with the USA or the UK, the German real estate industry and real estate market still lack transparency and are characterized by information asymmetries and opaqueness.Originality/valueThe results indicate that the German real estate market and industry become more mature and bit by bit converge with their US and UK archetype.

Study on the Effect of V Microalloying on Earthquake Resisting High-Strength Reinforcing Bar Steels

2021 ◽  
Vol 1016 ◽  
pp. 345-353
Author(s):  
Junho Chung ◽  
Taeh Yung Kim ◽  
Ju Sang Lee
Keyword(s):  
Seismic Performance ◽  
High Strength ◽  
Social Needs ◽  
Alloying Elements ◽  
Reinforcing Bars ◽  
Reinforcing Bar ◽  
Fine Grain ◽  
The Social ◽  
Microstructural Evaluation ◽  
Tempcore Process

Recently, the frequency of earthquakes has been increasing worldwide. As a result, steel reinforced with seismic performance that can satisfy the social needs to strengthen the existing seismic performance of existing infrastructure facilities and new buildings has become important. In general, to secure the yield strength of reinforcing bars and to reduce the production cost, reinforcing bars are produced by rolling the surface through a facility such as a Tempcore. In Korea, most of them have adopted the Tempcore process to ensure the mechanical requirements of the product. However, the use of a small amount of alloying elements and the application of Tempcore have limitations in producing reinforcing bars that require seismic performance. In recent years, remarkable progress has been made in the production and application of high strength rebars. Microalloying and fine-grain strengthening are the most effective methods in developing high strength rebars. That is, the precipitation of V (C, N) is promoted by the addition of V to improve the strength by precipitation strengthening of V-carbonitride. However, in V-microalloyed reinforcing bars, it was confirmed that the required strength did not increase proportional to the amount of V added. In this study, the effects of vanadium and other alloying elements on the mechanical properties and yield ratio of steel bars were investigated by tensile test results and microstructural evaluation.

Investigation of Lath and Plate Martensite in a Carbon Steel

2011 ◽  
Vol 172-174 ◽  
pp. 61-66 ◽  
Author(s):  
Albin Stormvinter ◽  
Annika Borgenstam ◽  
Peter Hedström
Keyword(s):  
Carbon Steel ◽  
Carbon Content ◽  
Morphological Change ◽  
Retained Austenite ◽  
Alloy Composition ◽  
Lath Martensite ◽  
Carbon Steels ◽  
Plate Martensite ◽  
High Carbon ◽  
Martensite Microstructure

Martensite in carbon steels forms in different morphologies, often referred to as lath andplate martensite. The alloy composition has a strong effect on the morphology, for instance in car-bon steels there is a morphological change of the martensite microstructure from lath martensite atlow carbon contents to plate martensite at high carbon contents. In the present work a decarburizedhigh-carbon steel, enabling the isolation of carbons' influence alone, has been studied in order to in-vestigate the changes in morphology and hardness. From the results it is concluded that there is acontinuous change of hardness with increased carbon content. The increasing hardness slows down atabout 0.6 wt%C before decreasing at higher carbon contents. This is in accordance with the change inmorphology since it was found that lath martensite dominates below 0.6 wt%C and the first units ofgrain boundary martensite and plate martensite appear above 0.6 wt%C. At high carbon contents thedominating morphology is plate martensite, but retained austenite is also present.

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