Effect of water flow rate on the yield strength of a reinforced bar
- Musonda, Vincent, Akinlabi, Esther Titilayo, Jen, Tien-Chien
- Authors: Musonda, Vincent , Akinlabi, Esther Titilayo , Jen, Tien-Chien
- Date: 2017
- Subjects: Hot rolling , Microstructure , Rebar
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/370699 , http://hdl.handle.net/10210/243763 , uj:25198 , Citation: Musonda, V., Akinlabi, E.T. & Jen, T.C. 2017. Effect of water flow rate on the yield strength of a reinforced bar. Advances in Engineering Research (AER), volume 102, Second International Conference on Mechanics, Materials and Structural Engineering (ICMMSE 2017).
- Description: Abstract: High strength requirement of Thermo-mechanically treated (TMT) rebars is crucial in the construction of flyovers, bridges and high rise buildings because of the good combination of the mechanical properties. The yield strength is expected to be between 450 MPa and 550 MPa after the hot rolling process depending on prescribed standards. A series of experimental trials during a hot rolling process were carried out in a steel plant in which parameters such as the water flow rate and the processing time were varied to study their effect on the evolving mechanical properties of the rebars. Four “heats”(A “heat” is a batch of molten steel, referred to as tap to tap cycle and involves furnace charging with scrap, melting, deslagging, tapping molten steel and furnace turn-around. Furnace turn-around is the period following completion of tapping until the furnace is recharged for the next “heat”) were done to produce Y 12 mm reinforced bars (rebars). For every “heat” done, tensile tests were carried out on the samples every after 15 minutes to establish the yield strength of the rebar. At least eight samples were tested in every “heat”. It was observed that some samples showed low values of yield strength (< 450 MPa) which falls short of the minimum guaranteed yield strength. It was further noted that the water flow rate in the water cooling chamber was far below 600 m⁄h for this size of rebar in some cases. A series of these tests were conducted and the water flow rate adjusted in order to arrive at the optimum flow rate corresponding to the expected yield strength and microstructure. The quenching time in the water cooling chamber was in the range 0.1 to 0.5 seconds and the results obtained both for the tensile tests and microstructure after several adjustments to the flow rate in particular yielded optimum results consistent with prescribed standards.
- Full Text:
- Authors: Musonda, Vincent , Akinlabi, Esther Titilayo , Jen, Tien-Chien
- Date: 2017
- Subjects: Hot rolling , Microstructure , Rebar
- Language: English
- Type: Conference proceedings
- Identifier: http://ujcontent.uj.ac.za8080/10210/370699 , http://hdl.handle.net/10210/243763 , uj:25198 , Citation: Musonda, V., Akinlabi, E.T. & Jen, T.C. 2017. Effect of water flow rate on the yield strength of a reinforced bar. Advances in Engineering Research (AER), volume 102, Second International Conference on Mechanics, Materials and Structural Engineering (ICMMSE 2017).
- Description: Abstract: High strength requirement of Thermo-mechanically treated (TMT) rebars is crucial in the construction of flyovers, bridges and high rise buildings because of the good combination of the mechanical properties. The yield strength is expected to be between 450 MPa and 550 MPa after the hot rolling process depending on prescribed standards. A series of experimental trials during a hot rolling process were carried out in a steel plant in which parameters such as the water flow rate and the processing time were varied to study their effect on the evolving mechanical properties of the rebars. Four “heats”(A “heat” is a batch of molten steel, referred to as tap to tap cycle and involves furnace charging with scrap, melting, deslagging, tapping molten steel and furnace turn-around. Furnace turn-around is the period following completion of tapping until the furnace is recharged for the next “heat”) were done to produce Y 12 mm reinforced bars (rebars). For every “heat” done, tensile tests were carried out on the samples every after 15 minutes to establish the yield strength of the rebar. At least eight samples were tested in every “heat”. It was observed that some samples showed low values of yield strength (< 450 MPa) which falls short of the minimum guaranteed yield strength. It was further noted that the water flow rate in the water cooling chamber was far below 600 m⁄h for this size of rebar in some cases. A series of these tests were conducted and the water flow rate adjusted in order to arrive at the optimum flow rate corresponding to the expected yield strength and microstructure. The quenching time in the water cooling chamber was in the range 0.1 to 0.5 seconds and the results obtained both for the tensile tests and microstructure after several adjustments to the flow rate in particular yielded optimum results consistent with prescribed standards.
- Full Text:
Effect of weight per meter of reinforced bar on mechanical properties and microstructure
- Musonda, V., Akinlabi, Esther Titilayo, Jen, T.C.
- Authors: Musonda, V. , Akinlabi, Esther Titilayo , Jen, T.C.
- Date: 2017
- Subjects: Billets , Hot rolling , Microstructure
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/241963 , uj:24945 , Citation: Musonda, V., Akinlabi, E.T. & Jen, T.C. 2017. Effect of weight per meter of reinforced bar on mechanical properties and microstructure.
- Description: Abstract: Reinforced bars (rebars) are Thermo-mechanically treated (TMT) bars hot rolled from steel billets produced from scrap melted in an Electric Arc Furnace (EAF) at a temperature of about 1600 ℃ (usually 1580℃). Weight per meter of a low carbon steel rebar is one aspect which has been neglected by some steel producers during the tensile testing in the rod mill. Determination of weight per metre is explicitly required for a TMT rebar. Any reduction in mass will mean a lowering in capacity of the steel reinforcing bar. A series of “heat” numbers or batches of molten steel from an EAF for the production of steel sample A, (Y10 and Y 12 rebars), were observed at a Steel plant to investigate the effect of weight per meter of reinforced bar on the mechanical properties and microstructure. The rolling speed range was 3m/s to 14 m/s for different “heats”. Two other steel samples B and C were sourced from the local market to compare with Sample A. Samples collected from different sources on the local market, however, showed lower values of weight per meter different from the prescribed standards. This did not only affect the ultimate tensile strengths which were higher than normal but also the microstructure which deviated from the standard for this material. Sample A, did not only show a good combination of tensile strength and yield stress of 450MPa and a maximum tensile strength of 650MPa but also a standard pearliteferrite microstructure, while sample B and C exhibited excessive high strengths and brittle behaviour and can be prone to failure.
- Full Text:
- Authors: Musonda, V. , Akinlabi, Esther Titilayo , Jen, T.C.
- Date: 2017
- Subjects: Billets , Hot rolling , Microstructure
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/241963 , uj:24945 , Citation: Musonda, V., Akinlabi, E.T. & Jen, T.C. 2017. Effect of weight per meter of reinforced bar on mechanical properties and microstructure.
- Description: Abstract: Reinforced bars (rebars) are Thermo-mechanically treated (TMT) bars hot rolled from steel billets produced from scrap melted in an Electric Arc Furnace (EAF) at a temperature of about 1600 ℃ (usually 1580℃). Weight per meter of a low carbon steel rebar is one aspect which has been neglected by some steel producers during the tensile testing in the rod mill. Determination of weight per metre is explicitly required for a TMT rebar. Any reduction in mass will mean a lowering in capacity of the steel reinforcing bar. A series of “heat” numbers or batches of molten steel from an EAF for the production of steel sample A, (Y10 and Y 12 rebars), were observed at a Steel plant to investigate the effect of weight per meter of reinforced bar on the mechanical properties and microstructure. The rolling speed range was 3m/s to 14 m/s for different “heats”. Two other steel samples B and C were sourced from the local market to compare with Sample A. Samples collected from different sources on the local market, however, showed lower values of weight per meter different from the prescribed standards. This did not only affect the ultimate tensile strengths which were higher than normal but also the microstructure which deviated from the standard for this material. Sample A, did not only show a good combination of tensile strength and yield stress of 450MPa and a maximum tensile strength of 650MPa but also a standard pearliteferrite microstructure, while sample B and C exhibited excessive high strengths and brittle behaviour and can be prone to failure.
- Full Text:
Three-dimensional simulation of a single pass hot rolling of carbon steel : case of instabilities in steady state region
- Musonda, V., Akinlabi, Esther Titilayo
- Authors: Musonda, V. , Akinlabi, Esther Titilayo
- Date: 2018
- Subjects: Instabilities , Steady-state , Hot rolling
- Language: English
- Type: Conference proceeding
- Identifier: http://hdl.handle.net/10210/291112 , uj:31606 , Citation: Musonda, V. & Akinlabi, E.T. 2018. Three-dimensional simulation of a single pass hot rolling of carbon steel : case of instabilities in steady state region.
- Description: Abstract: The nature of instabilities in the steady-state region in the form of high amplitudes or peaks during hot rolling can be an indication of the problems in the roll mill stand. The aim of this study is to predict the variation in load, stress, strain, torque and power and the influence these parameters can have during the deformation of the workpiece in the roll gap. To achieve this aim, Finite Element Modelling (FEM) was used in the simulation of a single pass hot rolling of AISI 1016 carbon steel. The results indicate that, large amplitudes in the stresses, strains and torque variations can result in vibrations in the mill stands compared to the steady state point values. This can also result in inhomogeneity in the microstructural properties of the rolled workpiece...
- Full Text:
- Authors: Musonda, V. , Akinlabi, Esther Titilayo
- Date: 2018
- Subjects: Instabilities , Steady-state , Hot rolling
- Language: English
- Type: Conference proceeding
- Identifier: http://hdl.handle.net/10210/291112 , uj:31606 , Citation: Musonda, V. & Akinlabi, E.T. 2018. Three-dimensional simulation of a single pass hot rolling of carbon steel : case of instabilities in steady state region.
- Description: Abstract: The nature of instabilities in the steady-state region in the form of high amplitudes or peaks during hot rolling can be an indication of the problems in the roll mill stand. The aim of this study is to predict the variation in load, stress, strain, torque and power and the influence these parameters can have during the deformation of the workpiece in the roll gap. To achieve this aim, Finite Element Modelling (FEM) was used in the simulation of a single pass hot rolling of AISI 1016 carbon steel. The results indicate that, large amplitudes in the stresses, strains and torque variations can result in vibrations in the mill stands compared to the steady state point values. This can also result in inhomogeneity in the microstructural properties of the rolled workpiece...
- Full Text:
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