- Email: [email protected]
Residual stress measurement by strain gauge and X-ray diffraction method in different shaped rails
Engineering Failure Analysis 96 (2019) 525–529
Contents lists available at ScienceDirect
Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal
Short Communication
Residual stress measurement by strain gauge and X-ray diffraction method in different shaped rails
T
⁎
Muhammet Emre Turan , Fatih Aydin, Yavuz Sun, Melik Cetin Karabuk University, Iron and Steel Instıtute, Karabuk, Turkey
A R T IC LE I N F O
ABS TRA CT
Keywords: Residual stress Strain gauge X-ray diffraction R260 R260 grooved
It is well known that rails are the most important part of railway infrastructure. Besides good wear and fatigue resistance, appropriate residual stress value in rails is required to improve performance of rails. The knowledge of residual stress types and distributions gives prediction the mechanical properties of materials for manufacturer. This study aims to make comparison between destructive and non-destructive residual stress measurement techniques and to investigate the influence of rail head geometry on residual stress by the use of two different quality rails. One of the rails is R260 grade and the other one is R260 grooved rail. In addition to residual stress measurement with strain gauge (cutting) and X-ray diffraction method, microstructures of the specimens were examined. Results show that grooved rail has higher residual stress and different types of stress were observed for samples which are supported by X-ray and strain gauge method.
1. Introduction Nowadays, residual stress is one of the most important issue in railways [1]. It is known an elastic stress and also existed in materials owing to inhomogenous deformation [2]. Residual stress which includes heat capacity, thermal conductivity, plasticity, kinetics of transformations effects the characteristics of materials [3]. It stays in rail steels after rolling, straightening and cooling process [4]. Therefore, residual stress is an substantial parameter to estimate the mechanical behavior of rails. Residual stress can be generally categorized as two types. Tensile residual stress can lead to premature damage so it has negative effect for mechanical properties of materials. Compressive residual stress enhances the fatigue life so it prevents crack formations and propagations [5]. Measurement of residual stress is a necessary issue regarding to understand mechanical performance of materials. If the residual stress distribution and types of stress are known, fatigue and tensile properties of specimens can be predicted [5–7]. In decades, measurement techniques have been developed to obtain the knowledge of residual stress values. There are two types of measurement techniques are given in Fig. 1. Destructive methods are called as mechanical methods (stress release testing). Residual stress is measured by cutting piece or removing layer from base materials. Cutting and hole drilling are common methods because these methods are clearity and have a lot of experience in practical applications. These are advantages of mechanical methods. On the other hand, non-destructive method is based on physical methods. X-ray diffraction and magnetic methods are preffered for measurement especially in small specimens. There is no damage in specimen for physical methods while damage also occurs in mechanical methods [9]. By the use of these techniques, numerous studies have been performed to measure residual stress [10,11]. One study is about residual stress measurement in rails with X-ray diffraction method and other methods reveals that plastic deformation is an effective
⁎
Corresponding author. E-mail address: [email protected] (M.E. Turan).
https://doi.org/10.1016/j.engfailanal.2018.10.016 Received 22 June 2018; Received in revised form 6 October 2018; Accepted 22 October 2018 Available online 23 October 2018 1350-6307/ © 2018 Elsevier Ltd. All rights reserved.
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Fig. 1. Residual stress measurement techniques [8].
process to produce residual stress [12]. Huen et al. have investigated residual stress measurement using x-ray diffraction and impact indentation method in heavy rails with different points (head, bottom and waist) [13]. In this study, two different grades rails were used. One of them is R260 quality and the other rail is R260 grooved. R260 grade rail is generally preferred in railways and R260 grooved is produced for tram tracks [14]. These two grades rails have different rail geometry and they are shown in Fig. 2. The aim of this study is to compare destructive (Strain gauge) and non-destructive techniques (X-ray diffraction method) for residual stress measurement. To the best of our knowledge, there is no relationship between these to methods as a mathematically. The other purpose is also to understand the effect of rail geometry in head parts on residual stress behavior. 2. Experimental studies Rail samples used in this study are R260 and R260 grooved grade rails. The chemical compositions of the steels are presented in Table 1. Two quality rails have about similar chemical compositions. Their compositions are consistent with relevant standard (EN 13674–1). One meter long rails were used to measure residual stress by Strain gauge (cutting) method. Firstly, strain gauge was attached on the middle of the rail foot after the surface preparing process had been applied in order not to change of residual stress values. Then cutting process was performed to extract 20 mm slides from the base material. Samples were mechanically ground with SiC grinding paper then polishing was completed by the use of 6, 3 and 1 μm polishing solution respectively for metallographic process to analyze microstructure and measure residual stress with X-ray diffraction method. Etching process was applied with 3% Nital (Nitric acid and alcohol). Microstructures of the specimens were examined by Carl Zeiss Ultra Plus SEM device. Cu based X-ray diffraction machine (Rigaku Ultima IV XRD) was used for residual stress measurement by non-destructive method. The sin2ψ method was applied for the stress analysis with various tilt angles (−45°, −36.5°, −29°, −20°, 0°) for two rail samples and elastic modulus was kept constant (E = 207 GPa). Poisson ratio was taken 0,3 for each sample. The device was operated at 40 kV and 40 mA for measurements. The equation of sin2ψ method was given below [15],
d ϕψ − d 0 d0
=
1+v v σϕsin2 ψ − (σ11 + σ22) E E
(1)
where dφψ is measured spacing of diffracting plane, d0 is the lattice spacing, E is elastic modulus and ν is Poisson's ratio. So as to calculate residual stress in samples, the slope of dφψ-sin2ψ plot was used in accordance with Eq. Error! Reference source not found.).
Fig. 2. The images of R260 and R260 grooved rails. 526
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Table 1 Chemical composition of rails (wt%). Grade
C
Mn
Si
P
Cr
Ni
S
Al
Mo
R260 R260 grooved
0.75 0.76
0.93 0.91
0.33 0.35
0.025 0.017
0.047 0.041
0.095 0.081
0.021 0.025
0.011 0.011
0.029 0.029
3. Results and discussions 3.1. Microstructure analysis SEM microstructures of the rails are shown in Fig. 3. R260 quality rail has coarse pearlitic microstructure. Fig. 3b) shows the R260 grooved rail that consists of pearlite and α-ferrite formation. However, similar chemical compositions have also seen in Table 1 and carbon contents are about 0.7% for each sample. So, the structures are about fully pearlitic. 3.2. Residual stress measurement results by strain gauge (cutting) method Graphics belonging to the samples are shown in Fig. 4. Two cutting processes were applied. Blue line in the graphic shows a first cutting and red line shows a second cutting for each sample. First cutting value is always accepted as ‘0’ (zero) for balancing the strain gauge. It is concluded that the residual stress is directly the secondary cutting values. After the cutting, the strain data is obtained from the software program, then residual stress is calculated by multiplying the difference between the before and after values of the cutting process with Elastic Modulus. Elastic Modulus was accepted as 207,000 MPa.
σlongitudinal = −E . ε
(2)
Net strain value for R260 quality rail is 720 μm/m. When Hooke law is used to obtain stress value, residual stress is found as 148 MPa for this rail. Also there is a tensile residual stress in material because the graphic lines for this sample are towards to the negative region. On the other hand, R260 grooved rail has compressive residual stress. Strain and residual stress values are found 777 μm/m and 160 MPa respectively. Furthermore, both these residual stress values must be lower than 250 MPa in the EN 13674–1 railway standard. So two quality of rails have appropriate residual stress. There is only difference between two rails. One of them has tensile stress and the other has compressive residual stress. It may be concluded from the results, R260 grooved rail might show better mechanical properties such as fatigue behavior. Because tensile stress causes crack propagation so fracture and brittle in specimens are occurred. But compressive strength prevents the crack formation and development [16]. 3.3. Residual stress measurement results by X-ray diffraction method XRD residual stress data was fitted with various tilt (psi) angles in the BCC iron (222) diffraction planes and detection was obtained at about 136.900o in Fig. 5. A good linearity of data shows that sin2ψ method is applicable for the investigated rails and their surfaces. It can be deduced that the linearity also signals the absence of shear stresses and textures on the relevant surfaces. Residual stress values obtained from the slopes of these plots are presented in Table 2. The results clearly show a tendency for gaining large compressive stresses with for R260 grooved rail. To sum up, there is a same trend with strain gauge (cutting) method. R260 grooved rail has higher residual stress than R260 grade rail. But compressive residual stress is a dominant that can be seen especially by cutting method clearly. Strain gauge (Cutting) method is valid for residual stress measurement in rails according to the standard because of applicable technique for bigger parts of specimens. On the other hand, X-ray diffraction method is not related in standard but also it has potential applications for a lot of engineering materials. This technique was tried in addition to strain gauge method. The values were higher than accepted residual stress value from the standard. But it can be concluded that residual stress can be measured easily without any damage in this
Fig. 3. Microstructures of rails A) R260 B) R260 grooved. 527
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Fig. 4. Residual stress measurements of the samples (a) R260 (b) R260 grooved.
Fig. 5. The 2Ɵ degree versus sin2 psi plot of the samples (a) R260, (b) R260 grooved.
Table 2 Residual stress measurement results by X-ray diffraction. Rail qualities
Residual stress (MPa)
R260 R260 Grooved
−292.41 ± 15.83 −367.12 ± 26.25
technique. The applicable of X-ray diffraction method might be developed in future for rails. 3.4. Relationship between strain gauge and X-ray diffraction method The applicable of X-ray diffraction method might be developed in future for rails. In this study, 10 more R260 quality rails were tested by two techniques in order to make relation between Strain gauge and X-ray diffraction methods. All results were presented in Fig. 6. It can be concluded that there is a direct proportional. When all results are examined, following formula is obtained according to the residual stress values of 10 different rails. (3)
X. D. M = 2.10 x S. G. M X.D.M = X-ray Diffraction method.S.G.M = Strain Gauge method. 4. Conclusions
Residual stress of rails was measured successfully by the use of two different techniques. Once the results are evaluated, findings are listed as below: - R260 grooved rail has higher residual stress than that of R260 grade rails. Two measurement techniques (Strain gauge and X-ray diffraction) are consistent in terms of stress comparisons between two quality rails. 528
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Fig. 6. Residual stress measurement values by strain gauge and X-ray diffraction.
- Compressive residual stress can be observed applying plastic deformation on head part of rails. While R260 grooved rail has compressive residual stress, R260 grade has tensile residual stress. This situation can be seen clearly from the strain gauge method. Therefore, rail geometry can affect the residual stress types and distributions. References [1] R.M. Nejad, Using three-dimensional finite element analysis for simulation of residual stresses in railway wheels, Eng. Fail. Anal. 45 (2014) 449–455. [2] Q. Pan, Y. Ren, Y. Wei, et al., The method of residual stress gradient measurement based on ultrasonic technology, IEEE International Conference on Mechatronics and Automation (2016) 1215–1220. [3] G.E. Totten, Handbook of Residual Stress and Deformation of Steel, ASM International, 2002. [4] H. Song, J. Yang, L. Song, J. Yao, et al., Study on the steel rail rolling contact stress with consideration of initial residual stress, MATEC Web of Conferences 22 (2015). [5] M.E. Turan, S. Ozcelik, F. Husem, et al., The effect of head hardening process on the residual stress of rails, Proc. IMechE. Part F: J Rail and Rapid Transit (2016) 1–7. [6] P.J. Withers, M. Turski, L. Edwards, et al., Recent advances in residual stress measurement, Int. J. Press. Vessel. Pip. 85 (3) (2008) 118–127. [7] S.B. Dronavalli, “Residual stress measurements and analysis by destructive and non-destructive techniques ” M.S. Thesis. University of Nevada, Las Vegas (2004) 3. [8] M. E. Turan, S. Ozcelik, H. Zengin et al., “Resıdual stress measurement in raıls by destructıve and non destructıve method” Metal 2015 Conference. [9] P.J. Withers, H.K.D.H. Bhadeshia, Residual stress. Part 1- Measurement techniques, Mater. Sci. Technol. 17 (2013) 355–365. [10] H. Xue, L. Yan, R. Ge, Y. Ma, et al., Residual stress research on heavy rail using X-ray diffraction and impact indentation method ISRME, (2015), pp. 719–722. [11] H. Xue, R.F. Li, L. Yu, et al., The welding residual stress analysis on high performance bridge steel with different testing method, Adv. Mater. Res. 989–994 (2014) 883–886. [12] R.M. Nejad, M. Shariati, K. Farhangdoost, 3D finite element simulation of residual stresses in UIC60 rails during the quenching process, Therm. Sci. 21 (3) (2017) 1301–1307. [13] J. Kelleher, M.B. Prime, D. Buttle, et al., The measurement of residual stress in railway rails by diffraction and other methods, J. Neutron Res. 11 (4) (2003) 187–193. [14] S. Lakušić, M. Ahac, Hardness distribution over cross-section of grooved rails, Grad Jevinar 64 (12) (2012) 1009–1018. [15] C. Wang, T. Luo, J. Zhou, Y. Yang, Effects of solution and quenching treatment on the residual stress in extruded ZK60 magnesium alloy, Mater. Sci. Eng. A 722 (2018) 14–19. [16] Y. Osman, D. Murat, H. Selçuk, Tabaka kaldırma yöntemi ile kalıntı gerilmelerin ölçülmesi ve diğer yöntemlerle karşılaştırılması Mühendis ve Makina, 579 (49) (2008) 20–27.
529
Contents lists available at ScienceDirect
Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal
Short Communication
Residual stress measurement by strain gauge and X-ray diffraction method in different shaped rails
T
⁎
Muhammet Emre Turan , Fatih Aydin, Yavuz Sun, Melik Cetin Karabuk University, Iron and Steel Instıtute, Karabuk, Turkey
A R T IC LE I N F O
ABS TRA CT
Keywords: Residual stress Strain gauge X-ray diffraction R260 R260 grooved
It is well known that rails are the most important part of railway infrastructure. Besides good wear and fatigue resistance, appropriate residual stress value in rails is required to improve performance of rails. The knowledge of residual stress types and distributions gives prediction the mechanical properties of materials for manufacturer. This study aims to make comparison between destructive and non-destructive residual stress measurement techniques and to investigate the influence of rail head geometry on residual stress by the use of two different quality rails. One of the rails is R260 grade and the other one is R260 grooved rail. In addition to residual stress measurement with strain gauge (cutting) and X-ray diffraction method, microstructures of the specimens were examined. Results show that grooved rail has higher residual stress and different types of stress were observed for samples which are supported by X-ray and strain gauge method.
1. Introduction Nowadays, residual stress is one of the most important issue in railways [1]. It is known an elastic stress and also existed in materials owing to inhomogenous deformation [2]. Residual stress which includes heat capacity, thermal conductivity, plasticity, kinetics of transformations effects the characteristics of materials [3]. It stays in rail steels after rolling, straightening and cooling process [4]. Therefore, residual stress is an substantial parameter to estimate the mechanical behavior of rails. Residual stress can be generally categorized as two types. Tensile residual stress can lead to premature damage so it has negative effect for mechanical properties of materials. Compressive residual stress enhances the fatigue life so it prevents crack formations and propagations [5]. Measurement of residual stress is a necessary issue regarding to understand mechanical performance of materials. If the residual stress distribution and types of stress are known, fatigue and tensile properties of specimens can be predicted [5–7]. In decades, measurement techniques have been developed to obtain the knowledge of residual stress values. There are two types of measurement techniques are given in Fig. 1. Destructive methods are called as mechanical methods (stress release testing). Residual stress is measured by cutting piece or removing layer from base materials. Cutting and hole drilling are common methods because these methods are clearity and have a lot of experience in practical applications. These are advantages of mechanical methods. On the other hand, non-destructive method is based on physical methods. X-ray diffraction and magnetic methods are preffered for measurement especially in small specimens. There is no damage in specimen for physical methods while damage also occurs in mechanical methods [9]. By the use of these techniques, numerous studies have been performed to measure residual stress [10,11]. One study is about residual stress measurement in rails with X-ray diffraction method and other methods reveals that plastic deformation is an effective
⁎
Corresponding author. E-mail address: [email protected] (M.E. Turan).
https://doi.org/10.1016/j.engfailanal.2018.10.016 Received 22 June 2018; Received in revised form 6 October 2018; Accepted 22 October 2018 Available online 23 October 2018 1350-6307/ © 2018 Elsevier Ltd. All rights reserved.
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Fig. 1. Residual stress measurement techniques [8].
process to produce residual stress [12]. Huen et al. have investigated residual stress measurement using x-ray diffraction and impact indentation method in heavy rails with different points (head, bottom and waist) [13]. In this study, two different grades rails were used. One of them is R260 quality and the other rail is R260 grooved. R260 grade rail is generally preferred in railways and R260 grooved is produced for tram tracks [14]. These two grades rails have different rail geometry and they are shown in Fig. 2. The aim of this study is to compare destructive (Strain gauge) and non-destructive techniques (X-ray diffraction method) for residual stress measurement. To the best of our knowledge, there is no relationship between these to methods as a mathematically. The other purpose is also to understand the effect of rail geometry in head parts on residual stress behavior. 2. Experimental studies Rail samples used in this study are R260 and R260 grooved grade rails. The chemical compositions of the steels are presented in Table 1. Two quality rails have about similar chemical compositions. Their compositions are consistent with relevant standard (EN 13674–1). One meter long rails were used to measure residual stress by Strain gauge (cutting) method. Firstly, strain gauge was attached on the middle of the rail foot after the surface preparing process had been applied in order not to change of residual stress values. Then cutting process was performed to extract 20 mm slides from the base material. Samples were mechanically ground with SiC grinding paper then polishing was completed by the use of 6, 3 and 1 μm polishing solution respectively for metallographic process to analyze microstructure and measure residual stress with X-ray diffraction method. Etching process was applied with 3% Nital (Nitric acid and alcohol). Microstructures of the specimens were examined by Carl Zeiss Ultra Plus SEM device. Cu based X-ray diffraction machine (Rigaku Ultima IV XRD) was used for residual stress measurement by non-destructive method. The sin2ψ method was applied for the stress analysis with various tilt angles (−45°, −36.5°, −29°, −20°, 0°) for two rail samples and elastic modulus was kept constant (E = 207 GPa). Poisson ratio was taken 0,3 for each sample. The device was operated at 40 kV and 40 mA for measurements. The equation of sin2ψ method was given below [15],
d ϕψ − d 0 d0
=
1+v v σϕsin2 ψ − (σ11 + σ22) E E
(1)
where dφψ is measured spacing of diffracting plane, d0 is the lattice spacing, E is elastic modulus and ν is Poisson's ratio. So as to calculate residual stress in samples, the slope of dφψ-sin2ψ plot was used in accordance with Eq. Error! Reference source not found.).
Fig. 2. The images of R260 and R260 grooved rails. 526
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Table 1 Chemical composition of rails (wt%). Grade
C
Mn
Si
P
Cr
Ni
S
Al
Mo
R260 R260 grooved
0.75 0.76
0.93 0.91
0.33 0.35
0.025 0.017
0.047 0.041
0.095 0.081
0.021 0.025
0.011 0.011
0.029 0.029
3. Results and discussions 3.1. Microstructure analysis SEM microstructures of the rails are shown in Fig. 3. R260 quality rail has coarse pearlitic microstructure. Fig. 3b) shows the R260 grooved rail that consists of pearlite and α-ferrite formation. However, similar chemical compositions have also seen in Table 1 and carbon contents are about 0.7% for each sample. So, the structures are about fully pearlitic. 3.2. Residual stress measurement results by strain gauge (cutting) method Graphics belonging to the samples are shown in Fig. 4. Two cutting processes were applied. Blue line in the graphic shows a first cutting and red line shows a second cutting for each sample. First cutting value is always accepted as ‘0’ (zero) for balancing the strain gauge. It is concluded that the residual stress is directly the secondary cutting values. After the cutting, the strain data is obtained from the software program, then residual stress is calculated by multiplying the difference between the before and after values of the cutting process with Elastic Modulus. Elastic Modulus was accepted as 207,000 MPa.
σlongitudinal = −E . ε
(2)
Net strain value for R260 quality rail is 720 μm/m. When Hooke law is used to obtain stress value, residual stress is found as 148 MPa for this rail. Also there is a tensile residual stress in material because the graphic lines for this sample are towards to the negative region. On the other hand, R260 grooved rail has compressive residual stress. Strain and residual stress values are found 777 μm/m and 160 MPa respectively. Furthermore, both these residual stress values must be lower than 250 MPa in the EN 13674–1 railway standard. So two quality of rails have appropriate residual stress. There is only difference between two rails. One of them has tensile stress and the other has compressive residual stress. It may be concluded from the results, R260 grooved rail might show better mechanical properties such as fatigue behavior. Because tensile stress causes crack propagation so fracture and brittle in specimens are occurred. But compressive strength prevents the crack formation and development [16]. 3.3. Residual stress measurement results by X-ray diffraction method XRD residual stress data was fitted with various tilt (psi) angles in the BCC iron (222) diffraction planes and detection was obtained at about 136.900o in Fig. 5. A good linearity of data shows that sin2ψ method is applicable for the investigated rails and their surfaces. It can be deduced that the linearity also signals the absence of shear stresses and textures on the relevant surfaces. Residual stress values obtained from the slopes of these plots are presented in Table 2. The results clearly show a tendency for gaining large compressive stresses with for R260 grooved rail. To sum up, there is a same trend with strain gauge (cutting) method. R260 grooved rail has higher residual stress than R260 grade rail. But compressive residual stress is a dominant that can be seen especially by cutting method clearly. Strain gauge (Cutting) method is valid for residual stress measurement in rails according to the standard because of applicable technique for bigger parts of specimens. On the other hand, X-ray diffraction method is not related in standard but also it has potential applications for a lot of engineering materials. This technique was tried in addition to strain gauge method. The values were higher than accepted residual stress value from the standard. But it can be concluded that residual stress can be measured easily without any damage in this
Fig. 3. Microstructures of rails A) R260 B) R260 grooved. 527
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Fig. 4. Residual stress measurements of the samples (a) R260 (b) R260 grooved.
Fig. 5. The 2Ɵ degree versus sin2 psi plot of the samples (a) R260, (b) R260 grooved.
Table 2 Residual stress measurement results by X-ray diffraction. Rail qualities
Residual stress (MPa)
R260 R260 Grooved
−292.41 ± 15.83 −367.12 ± 26.25
technique. The applicable of X-ray diffraction method might be developed in future for rails. 3.4. Relationship between strain gauge and X-ray diffraction method The applicable of X-ray diffraction method might be developed in future for rails. In this study, 10 more R260 quality rails were tested by two techniques in order to make relation between Strain gauge and X-ray diffraction methods. All results were presented in Fig. 6. It can be concluded that there is a direct proportional. When all results are examined, following formula is obtained according to the residual stress values of 10 different rails. (3)
X. D. M = 2.10 x S. G. M X.D.M = X-ray Diffraction method.S.G.M = Strain Gauge method. 4. Conclusions
Residual stress of rails was measured successfully by the use of two different techniques. Once the results are evaluated, findings are listed as below: - R260 grooved rail has higher residual stress than that of R260 grade rails. Two measurement techniques (Strain gauge and X-ray diffraction) are consistent in terms of stress comparisons between two quality rails. 528
Engineering Failure Analysis 96 (2019) 525–529
M.E. Turan et al.
Fig. 6. Residual stress measurement values by strain gauge and X-ray diffraction.
- Compressive residual stress can be observed applying plastic deformation on head part of rails. While R260 grooved rail has compressive residual stress, R260 grade has tensile residual stress. This situation can be seen clearly from the strain gauge method. Therefore, rail geometry can affect the residual stress types and distributions. References [1] R.M. Nejad, Using three-dimensional finite element analysis for simulation of residual stresses in railway wheels, Eng. Fail. Anal. 45 (2014) 449–455. [2] Q. Pan, Y. Ren, Y. Wei, et al., The method of residual stress gradient measurement based on ultrasonic technology, IEEE International Conference on Mechatronics and Automation (2016) 1215–1220. [3] G.E. Totten, Handbook of Residual Stress and Deformation of Steel, ASM International, 2002. [4] H. Song, J. Yang, L. Song, J. Yao, et al., Study on the steel rail rolling contact stress with consideration of initial residual stress, MATEC Web of Conferences 22 (2015). [5] M.E. Turan, S. Ozcelik, F. Husem, et al., The effect of head hardening process on the residual stress of rails, Proc. IMechE. Part F: J Rail and Rapid Transit (2016) 1–7. [6] P.J. Withers, M. Turski, L. Edwards, et al., Recent advances in residual stress measurement, Int. J. Press. Vessel. Pip. 85 (3) (2008) 118–127. [7] S.B. Dronavalli, “Residual stress measurements and analysis by destructive and non-destructive techniques ” M.S. Thesis. University of Nevada, Las Vegas (2004) 3. [8] M. E. Turan, S. Ozcelik, H. Zengin et al., “Resıdual stress measurement in raıls by destructıve and non destructıve method” Metal 2015 Conference. [9] P.J. Withers, H.K.D.H. Bhadeshia, Residual stress. Part 1- Measurement techniques, Mater. Sci. Technol. 17 (2013) 355–365. [10] H. Xue, L. Yan, R. Ge, Y. Ma, et al., Residual stress research on heavy rail using X-ray diffraction and impact indentation method ISRME, (2015), pp. 719–722. [11] H. Xue, R.F. Li, L. Yu, et al., The welding residual stress analysis on high performance bridge steel with different testing method, Adv. Mater. Res. 989–994 (2014) 883–886. [12] R.M. Nejad, M. Shariati, K. Farhangdoost, 3D finite element simulation of residual stresses in UIC60 rails during the quenching process, Therm. Sci. 21 (3) (2017) 1301–1307. [13] J. Kelleher, M.B. Prime, D. Buttle, et al., The measurement of residual stress in railway rails by diffraction and other methods, J. Neutron Res. 11 (4) (2003) 187–193. [14] S. Lakušić, M. Ahac, Hardness distribution over cross-section of grooved rails, Grad Jevinar 64 (12) (2012) 1009–1018. [15] C. Wang, T. Luo, J. Zhou, Y. Yang, Effects of solution and quenching treatment on the residual stress in extruded ZK60 magnesium alloy, Mater. Sci. Eng. A 722 (2018) 14–19. [16] Y. Osman, D. Murat, H. Selçuk, Tabaka kaldırma yöntemi ile kalıntı gerilmelerin ölçülmesi ve diğer yöntemlerle karşılaştırılması Mühendis ve Makina, 579 (49) (2008) 20–27.
529