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The effect of cyclic torsion on the dislocation structure of drawn mild steel
Aguilar, Maria Teresa Paulino;Corrêa, Elaine Carballo Siqueira;Monteiro, Waldemar Alfredo;Cetlin, Paulo Roberto;
Materials Research , 2006, DOI: 10.1590/S1516-14392006000300016
Abstract: cold forming is usually associated with the "work hardening" of the material being formed. the work hardening behavior of metals subject to complex processing paths is different from that in monotonic deformation. the results show that, after some initial hardening, there is a possibility that further deformation will cause softening in the material ("work softening"). recent work showed that cyclic torsion applied to drawn products causes changes in the subsequent tensile behavior of low carbon steel, and that the effect will depend on the previous "history" of the material. for annealed samples, the cyclic torsion leads to an increase in the yield strength, but does not affect the tensile strength and elongation. for the case of previously drawn bars, the cyclic deformation caused a decrease in the yield and tensile strength and an increase in the total elongation. the present paper discusses the dislocation structure changes associated with different strain paths in mild steel.
Experimental Study on the Mechanical Properties of FRP Bars by Hybridizing with Steel Wires  [PDF]
Ji-Hyun Hwang, Dong-Woo Seo, Ki-Tae Park, Young-Jun You
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.67039
Abstract:

Many studies on fiber reinforced polymer composite bars, as a substitute for reinforcing bars, have been conducted to solve corrosion of steel in reinforced concrete structures since 1960s’. However, FRP Bars have a lower elastic modulus than steel rebar as a structural component of concrete structures. Material properties with brittleness fracture and low elastic modulus can be improved by combining cheaper steel than carbon or aramid fibers. In this study, prototypes of FRP Bars with inserted steel wires (i.e., “FRP Hybrid Bars”) were developed and their tensile performance was compared depending on the proportion and diameter of steel. The FRP Hybrid Bars were made by dividing them into D13 and D16 according to the diameter and proportion of inserted wires: GFRPs were combined with wires having different diameters of 0.5 mm, 1.0 mm, and 2.0 mm in the proportion of 10%, 30%, 50%, and 70%, respectively. As a result of tensile tests, the elastic modulus of FRP Hybrid Bars were improved as 20% - 190% in comparison with the fully GFRP Bars.

EVALUACION DEL COMPORTAMIENTO DE BARRAS DE ACERO CON BAJO CONTENIDO DE CARBONO SOLDADAS A TOPE Y SOMETIDAS A CICLOS SEVEROS DE CARGA AXIAL EVALUATION OF THE BEHAVIOR OF BUTT-WELDT LOW-CARBON BARS OF STEEL AND SUBJECTED TO SEVERE CYCLES OF AXIAL LOAD
Enrique Castilla C,Aimé Guerrero,Norberto Fernández
Boletín Técnico , 2001,
Abstract: RESUMEN El presente estudio evalúa el comportamiento de barras para refuerzo con bajo contenido de carbono (ASTM A-706) soldadas a tope y sometidas a ciclos severos de carga pulsante. En tal sentido, se ensayaron 95 barras para todos los diámetros comerciales entre y 1 pulgada soldadas según lo establecido por la norma AWS D1.4. Un total de 55 barras eran de acero termotratado y las restantes 40 de acero microaleado. Una vez alcanzado el agotamiento de algunas muestras ensayadas, se determinaron a través de las técnicas de microscopía electrónica de barrido (M.E.B.) y espectrometría de energía dispersiva por rayos X (E.D.X.), las características microestructurales y fractográficas de las uniones soldadas del refuerzo estructural. Los resultados sugieren que las barras de acero microaleado son soldables a temperatura ambiente sin comprometer sus propiedades sismorresistentes. Para el caso de las barras de acero termotratado, los diámetros grandes (mayores o iguales a de pulgada) presentan restricciones en cuanto a su soldabilidad con fines sismorresistentes, por ser ellos posiblemente más sensibles al agrietamiento por hidrógeno. Se concluye también sobre la profundidad de temple para barras de acero termotratado que garanticen su comportamiento dúctil al ser soldadas a temperatura ambiente ABSTRACT This study evaluates the behavior of butt-welded low-carbon reinforcing bars (ASTM A-706) subjected to severe cycles of pulsating load. The tests covered 95 bars of all commercial diameters between #4 and #8, welded according to specifications set forth in AWS D1.4. Of these, a total of 55 were of thermo-treated steel and the remaining 40 were of micro-alloy steel. Once failure was reached in some of the tested specimens, the micro-structural and fractographic characteristics of the welded joints were determined using electronic microscope scanning and X-ray dispersive energy. The results suggest that micro-alloy steel bars can be welded at room-temperature without affecting their earthquake-resistant properties. In the case of thermo-treated steel bars, larger diameters (equal or greater than #6) show undesired behavior for earthquake-resistant use, perhaps because they are more sensitive to hydrogen cracking. Conclusions are also drawn as to the quench depth for thermo-treated steel bars which will guarantee ductile behavior when welded at room temperature
Mechanical Properties of Cold-Drawn Low Carbon Steel for Nail Manufacture: Experimental Observation  [cached]
N.A. Raji,O.O. Oluwole
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: The objective of this study is to investigate the influence of service situation on the mechanical properties of plain nails manufactured from low carbon steel. The influence of the degree of cold drawing on the mechanical properties and strain hardening of the material is investigated by tensile test experimentation. The stress-strain relationships of the cold-drawn low carbon steel were investigated over the 20, 25, 40 and 55% degree of drawn deformation for the manufacture of 4, 3, 2 and 2 inches nails, respectively. The true stress-strain curves were analyzed to obtain the yield strength and tensile strength of the cold drawn steel. It is shown that the yield strength, tensile strength, hardness and toughness of the low carbon steel reduce with increasing degree of cold-drawn deformation. The micrographs of the deformed samples obtained using optical microscope shows that the grain structure elongates in the direction of the drawing operation and misorientation of the grains set in at 40 and 55% degree of deformation. The difference in yield strength was attributed to the strain hardening, resulting from the different degrees of drawn deformation.
Nanostructure of a cold drawn tempered martensitic steel  [PDF]
Xavier Sauvage,Xavier Quelennec,Jean-Jacques Malandain,Philippe Pareige
Physics , 2006,
Abstract: The carbon atom distribution in a tempered martensitic steel processed by cold drawing was investigated with a three-dimensional atom probe. Data clearly show that cementite starts to decompose at the early stage of deformation. This indicates that the driving force of cementite decomposition during plastic deformation is not related to a strong increase of the interfacial energy. Carbon atmospheres were also analysed. They probably result from pipe diffusion of carbon atoms along dislocations pined by Fe3C carbides.
Effect of Soaking Time on the Mechanical Properties of Annealed Cold-Drawn Low Carbon Steel  [PDF]
Nurudeen Adekunle Raji, Oluleke Olugbemiga Oluwole
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.38072
Abstract: The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the annealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.
Weldability of Recycled Steel Bars in Uganda
Senfuka C,Kirabira J.B,Byauhanga J.K
International Journal of Engineering and Technology , 2012,
Abstract: The metallurgical reliability of welded recycled steel made in Uganda has been studied through the examination of manual metal arc weldments of steel samples of 0.27%C and less using the dye penetrant flaw detection method, micro-hardness plots and spark spectromentry. This method was selected to ensure reproducibility by taking repeated readings on the same sample since it is largely non-destructive. About thirteen percent of the samples exhibited post-weld cracks. Of these, 3% of the samples yielded hot cracks while the other 10% showed typical hydrogen assisted cracks. The cracking sensitivity has been attributed to the presence of large numbers and quantities of residual elements rather than high carbon content in particular. This resulted from the predominantly recycled production mode in the country. The use of more elaborate refining methods and the exploitation of virgin iron resources have been recommended. Pre- and post-heating techniques have been advised whenever weld cracking threatens.
Optimization of the Annealing Parameters for Improved Tensile Properties in Cold Drawn 0.12 wt% C Steel  [PDF]
Nurudeen A. Raji, Oluleke O. Oluwole
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.511106
Abstract:

Drawn low carbon steel is characterized by brittle fracture. These defects are associated with the poor ductility and high strain hardening due to the cold work. There is a need therefore to determine optimum heat treatment parameters that could ensure improved toughness and ductility. Determining the optimum annealing parameters ensures valued recrystallization and also minimizes grain growth that could be detrimental to the resulting product. 40% and 55% cold drawn steels were annealed at temperatures 500℃ to 650℃ at intervals of 50℃ and soaked for 10 to 60 minutes at interval of 10 minutes to identify the temperature range and soaking time where optimum combination of properties could be obtained. Tensile test and impact toughness experiments were done to determine the required properties of the steel. Polynomial regression analysis was used to fit the properties relationship with soaking time and temperatures and the classical optimization technique was used to determine the minimum soaking time and temperature required for improved properties of the steel. Annealing treatment at 588℃ for 11 minutes at grain size of 44.7 mm can be considered to be the optimum annealing treatment for the 40% cold drawn 0.12 wt% C steel and 539℃ for 17 minutes at grain size of 19.5 mm for the 55% cold drawn 0.12 wt% C steel.

Quantity Detection of Steel Bars Based on Deep Learning
Han Yang, Chenghua Fu
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105784
Abstract:
In the actual production environment, the number of steel bars in the con-struction site is mainly counted manually. For the special task of steel bar detection, a detection and counting method based on depth learning is proposed. The method is applied to the actual production environment in-stead of the traditional time-consuming and labor-consuming manual counting method. By comparing the traditional detection algorithm with the one-stage and two-stage detection in depth learning. After the algorithm and considering the efficiency of the model, the improved detection algorithm is proposed to adapt to the special task of steel bar detection. In the final evaluation index, the improved one-stage detection algorithm is superior to the improved detection algorithm in the special task of steel bar detection, showing the improvement of performance, and compared with the single-stage detection algorithm. The law has also been improved to a certain extent.
Theoretical and experimental aspects of the bimetallic reinforcement bars steel - steel resistant to corrosion rolling process  [PDF]
S. Sawicki,H. Dyja,S. Mróz,P. Szota
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: Bimetallic bars which possess higher corrosion resistance and mechanical properties, it is the new kind of bimetallic bars, which are better than standard bars. The bimetallic bars are more often applied in concrete construction.Design/methodology/approach: The simulations of the bar rolling were carried out using the Forge2007 commercial program.Findings: The use of non-corrosive steel on plating layer assures receipt on a high durability and esthetics bimetallic bars.Practical implications: Bimetallic bars are chiefly used in the building industry at production of concrete constructions, and as working elements in bridge building in aggressive environment.Originality/value: Production of bimetallic bars is very difficult. One from many problems during production bimetallic bars is assurance good strength of bimetallic layer bond.
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