Residual stress distribution and the concept of total fatigue stress in laser and mechanically formed commercially pure grade 2 titanium alloy plates
- Mjali, Kadephi V., Els-Botes, Annelize, Mashinini, Peter M.
- Authors: Mjali, Kadephi V. , Els-Botes, Annelize , Mashinini, Peter M.
- Date: 2018
- Subjects: Mechanical properties , Titanium , Residual stress
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/273165 , uj:29096 , Citation: Mjali, K.V., Els-Botes, A. & Mashinini, P.M. 2018. Residual stress distribution and the concept of total fatigue stress in laser and mechanically formed commercially pure grade 2 titanium alloy plates.
- Description: Abstract: This paper discusses the investigation of residual stresses developed as a result of mechanical and laser forming processes in commercially pure grade 2 Titanium alloy plates as well as the concept of total fatigue stress. The intention of the study was to bend the plates using the respective processes to a final radius of 120mm using both processes. The hole drilling method was used to measure residual strains in all the plates. High stress gradients were witnessed in the current research and possible cases analyzed and investigated. The effects of processing speeds and powers used also played a significant role in the residual stress distribution in all the formed plates. A change in laser power resulted in changes to residual stress distribution in the plates evaluated. This study also dwells into how the loads that are not normally incorporated in fatigue testing influence fatigue life of commercially pure grade 2 Titanium alloy plates...
- Full Text:
- Authors: Mjali, Kadephi V. , Els-Botes, Annelize , Mashinini, Peter M.
- Date: 2018
- Subjects: Mechanical properties , Titanium , Residual stress
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/10210/273165 , uj:29096 , Citation: Mjali, K.V., Els-Botes, A. & Mashinini, P.M. 2018. Residual stress distribution and the concept of total fatigue stress in laser and mechanically formed commercially pure grade 2 titanium alloy plates.
- Description: Abstract: This paper discusses the investigation of residual stresses developed as a result of mechanical and laser forming processes in commercially pure grade 2 Titanium alloy plates as well as the concept of total fatigue stress. The intention of the study was to bend the plates using the respective processes to a final radius of 120mm using both processes. The hole drilling method was used to measure residual strains in all the plates. High stress gradients were witnessed in the current research and possible cases analyzed and investigated. The effects of processing speeds and powers used also played a significant role in the residual stress distribution in all the formed plates. A change in laser power resulted in changes to residual stress distribution in the plates evaluated. This study also dwells into how the loads that are not normally incorporated in fatigue testing influence fatigue life of commercially pure grade 2 Titanium alloy plates...
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Non-destructive residual stress analysis and microstructural behaviour of laser deposited titanium and copper alloy
- Erinosho, Mutiu F., Akinlabi, Esther Titilayo
- Authors: Erinosho, Mutiu F. , Akinlabi, Esther Titilayo
- Date: 2017
- Subjects: Laser metal deposition , Microstructures , Residual stress
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/233517 , uj:23842 , Citation: Erinosho, M.F. & Akinlabi, E.T. 2017. Non-destructive residual stress analysis and microstructural behaviour of laser deposited titanium and copper alloy. 5th International Conference of Materials Processing and Characterization (ICMPC 2016).
- Description: Abstract: Titanium alloy (Grade 5) has been regarded as the most useful alloys for the aerospace applications, due to their light weight properties. The addition of copper to this alloy allows the improvement in the mechanical properties. The increase in the laser power has influenced the coarseness of the α-Ti lamella; and thus slows down the cooling rate during solidification. The X ray diffraction method has been used to analyse the residual stresses using the biaxial and shear-stressed model. Very infinitesimal microns were taken into consideration for the penetration depth. The results generated indicate that a decrease in the compressive residual stresses is attributed to the increase in the laser power and the variation of the heat input within the clad during processing. The differences in the thermal expansion with respect to the increase in the volume of deposition as the laser power increases have significant effect on the compressive residual stress.
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- Authors: Erinosho, Mutiu F. , Akinlabi, Esther Titilayo
- Date: 2017
- Subjects: Laser metal deposition , Microstructures , Residual stress
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/233517 , uj:23842 , Citation: Erinosho, M.F. & Akinlabi, E.T. 2017. Non-destructive residual stress analysis and microstructural behaviour of laser deposited titanium and copper alloy. 5th International Conference of Materials Processing and Characterization (ICMPC 2016).
- Description: Abstract: Titanium alloy (Grade 5) has been regarded as the most useful alloys for the aerospace applications, due to their light weight properties. The addition of copper to this alloy allows the improvement in the mechanical properties. The increase in the laser power has influenced the coarseness of the α-Ti lamella; and thus slows down the cooling rate during solidification. The X ray diffraction method has been used to analyse the residual stresses using the biaxial and shear-stressed model. Very infinitesimal microns were taken into consideration for the penetration depth. The results generated indicate that a decrease in the compressive residual stresses is attributed to the increase in the laser power and the variation of the heat input within the clad during processing. The differences in the thermal expansion with respect to the increase in the volume of deposition as the laser power increases have significant effect on the compressive residual stress.
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Residual stress characterization from numerical analysis of the multi-particle impact behavior in cold spray
- Moonga, Kando Hamiyanze, Jen, Tien-Chien
- Authors: Moonga, Kando Hamiyanze , Jen, Tien-Chien
- Date: 2017
- Subjects: Multiple particle impact , Cold spray , Residual stress
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/259242 , uj:27273 , Citation: Moonga, K.H. & Jen, T.C. 2017. Residual stress characterization from numerical analysis of the multi-particle impact behavior in cold spray.
- Description: Abstract: In cold spray, bonding is created between a substrate and the particles and between particles through impact deformation at high strain rates. A prominent feature of the cold spray process is the compressive residual stress that arises during the deposition process. Compressive residual stress on the surface can be beneficial for fatigue resistance. As a post processing technique several applications require surface treatment processes that produce this state of stress on component surfaces such as shot peening, laser shock peening, ultrasonic impact treatment, low plasticity burnishing, etc. In all of these methods the compressive stress is produced through plastic deformation of the surface region. In a similar manner, the cold spray process induces compressive stress by high speed impact of the sprayed particles on the surface, causing a peening effect. The effects of these variations in the properties of the coatings are rarely reported. Moreover there are some applications which require minimal residual stresses in the components such as in optics. In this study, we have investigated the residual stress using numerical analysis of the multi-particle impact behavior in cold spray.
- Full Text:
- Authors: Moonga, Kando Hamiyanze , Jen, Tien-Chien
- Date: 2017
- Subjects: Multiple particle impact , Cold spray , Residual stress
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/259242 , uj:27273 , Citation: Moonga, K.H. & Jen, T.C. 2017. Residual stress characterization from numerical analysis of the multi-particle impact behavior in cold spray.
- Description: Abstract: In cold spray, bonding is created between a substrate and the particles and between particles through impact deformation at high strain rates. A prominent feature of the cold spray process is the compressive residual stress that arises during the deposition process. Compressive residual stress on the surface can be beneficial for fatigue resistance. As a post processing technique several applications require surface treatment processes that produce this state of stress on component surfaces such as shot peening, laser shock peening, ultrasonic impact treatment, low plasticity burnishing, etc. In all of these methods the compressive stress is produced through plastic deformation of the surface region. In a similar manner, the cold spray process induces compressive stress by high speed impact of the sprayed particles on the surface, causing a peening effect. The effects of these variations in the properties of the coatings are rarely reported. Moreover there are some applications which require minimal residual stresses in the components such as in optics. In this study, we have investigated the residual stress using numerical analysis of the multi-particle impact behavior in cold spray.
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A numerical analysis of machining induced residual stresses of Grade 5 Titanium Alloy
- Laubscher, R. F., Styger, G., Oosthuizen, G.A.
- Authors: Laubscher, R. F. , Styger, G. , Oosthuizen, G.A.
- Date: 2014
- Subjects: Residual stress , Titanium alloys - Fracture
- Type: Article
- Identifier: uj:5088 , http://hdl.handle.net/10210/13664
- Description: In general most manufacturing techniques alter the surface integrity of the final component. Surface integrity refers to the surface properties and their influence on the functional performance of manufactured components1. Machining induced residual stress is a surface integrity descriptor that may have a significant influence on the mechanical behavior of metallic parts subjected to dynamic loads2. Most manufacturing processes introduce some form of residual stress to the material. Cutting or more specifically machining involves large plastic deformation and elevated temperatures that may induce significant residual stresses in the surface and near surface region. When turning steel these stresses are largely tensile in nature and extend to a depth of approximately 200 μm1.
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- Authors: Laubscher, R. F. , Styger, G. , Oosthuizen, G.A.
- Date: 2014
- Subjects: Residual stress , Titanium alloys - Fracture
- Type: Article
- Identifier: uj:5088 , http://hdl.handle.net/10210/13664
- Description: In general most manufacturing techniques alter the surface integrity of the final component. Surface integrity refers to the surface properties and their influence on the functional performance of manufactured components1. Machining induced residual stress is a surface integrity descriptor that may have a significant influence on the mechanical behavior of metallic parts subjected to dynamic loads2. Most manufacturing processes introduce some form of residual stress to the material. Cutting or more specifically machining involves large plastic deformation and elevated temperatures that may induce significant residual stresses in the surface and near surface region. When turning steel these stresses are largely tensile in nature and extend to a depth of approximately 200 μm1.
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Residual stress depth profiling of commercially pure titanium subjected to high-speed machining using energy dispersive diffraction
- Janse van Rensburg, N., Madyira, D.M., Laubscher, R.F., Oosthuizen, G.A.
- Authors: Janse van Rensburg, N. , Madyira, D.M. , Laubscher, R.F. , Oosthuizen, G.A.
- Date: 2013
- Subjects: Residual stress , Energy dispersive diffraction , Titanium - Mechanical properties
- Type: Article
- Identifier: uj:4948 , http://hdl.handle.net/10210/13048
- Description: Residual stress is well-known to influence the mechanical properties of machined components. The magnitude and distribution of these stresses are critical to determine the component’s life, specifically under fatigue loading. There exists a growing need to better understand the effects of cutting parameters on residual stress and to identify more innovative methods to evaluate residual stress. Titanium has been widely used, but many of the same qualities that enhance titanium’s appeal for most applications also contribute to it being one of the most difficult to machine materials. High-speed cutting experiments were conducted on commercially pure (CP) titanium and the residual stress depth profile was analysed using energy dispersive diffraction (EDDI). The residual stress depth profile of CP Grade 4 titanium was then evaluated. Experimental results show that cutting speed and depth of cut have a significant effect on the residual stress profile. At a low cutting speed, the surface residual stresses are largely compressive, becoming less compressive with an increase in cutting speed. An increase in depth of cut also introduces more compressive residual stresses into the material.
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- Authors: Janse van Rensburg, N. , Madyira, D.M. , Laubscher, R.F. , Oosthuizen, G.A.
- Date: 2013
- Subjects: Residual stress , Energy dispersive diffraction , Titanium - Mechanical properties
- Type: Article
- Identifier: uj:4948 , http://hdl.handle.net/10210/13048
- Description: Residual stress is well-known to influence the mechanical properties of machined components. The magnitude and distribution of these stresses are critical to determine the component’s life, specifically under fatigue loading. There exists a growing need to better understand the effects of cutting parameters on residual stress and to identify more innovative methods to evaluate residual stress. Titanium has been widely used, but many of the same qualities that enhance titanium’s appeal for most applications also contribute to it being one of the most difficult to machine materials. High-speed cutting experiments were conducted on commercially pure (CP) titanium and the residual stress depth profile was analysed using energy dispersive diffraction (EDDI). The residual stress depth profile of CP Grade 4 titanium was then evaluated. Experimental results show that cutting speed and depth of cut have a significant effect on the residual stress profile. At a low cutting speed, the surface residual stresses are largely compressive, becoming less compressive with an increase in cutting speed. An increase in depth of cut also introduces more compressive residual stresses into the material.
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