Investigation of Damage Growth by Measuring the Chord Modulus, Micro Hardness and Macro Hardness Variation in ST37 Steel

Document Type : Research Article

Authors

Department of mechanical engineering, university of tehran, iran

Abstract

In this paper, by using the theory of continuum damage mechanic and experimental methods, damage evolution is investigated. There are various experimental and theoretical methods for measuring the damage in materials. the experimental methods can be categorized in two type, i) destructive methods like analysis of chord modulus variation, and the ii) non-destructive methods like micro hardness or macro hardness evaluation. In this paper at the first, true stress - true strain diagram of material using the simple tension test and chord modulus variation using repetitive loading - unloading test is obtained. For measuring plastic strain, grids are etched on the tension sample by using electroetch device. And then by measuring major ellipsoid diameter on the broken sample and comparing with the preceding circle, plastic strain at different points is specified. At specified points of the sample, the micro hardness and the macro hardness are measured. Using the data of these three experimental methods, the corresponding damage is evaluated and the corresponding charts are plotted. Finally the evaluated damage by these three methods is compared. It is observed micro hardness and loading-unloading[1]tension test have relatively similar progress, but macro hardness progress had a significant difference with these two methods. It’s also observed, average of three methods is close to micro hardness method rather than two other.

Keywords

Main Subjects

References

[1]  S. Murakami, N. Ohno, A continuum theory of creep and creep damage, in:  Creep in structures, Springer, 1981, pp. 422-444.
[2]  C. Tasan, J. Hoefnagels, M. Geers, Indentation-based damage quantification revisited, Scripta materialia, 63(3)(2010)316-319.
[3]  J. Lemaitre, J. Dufailly, Damage measurements, Engineering Fracture Mechanics, 28(5-6) (1987) 643661.
[4]  X. Xu, Y. Dong, C. Fan, Laboratory investigation on energy dissipation and damage characteristics of frozen loess during deformation process, Cold Regions Science and Technology, 109 (2015) 1-8.
[5]  C. Cai, W. Ma, S. Zhao, Y. Mu, Experimental analysis and discussion on the damage variable of frozen loess, Advances in Materials Science and Engineering, 2017 (2017.
[6]  M. Ganjiani, Identification of damage parameters and plastic properties of an anisotropic damage model by micro-hardness measurements, International Journal of Damage Mechanics, 22(8) (2013) 1089-1108.
[7]  E. Bellenger, P. Bussy, Plastic and viscoplastic damage models with numerical treatment for metal forming processes, Journal of Materials Processing Technology, 80 (1998) 591-596.
[8]  B. Guelorget, M. François, J. Lu, Microindentation as a local damage measurement technique, Materials letters, 61(1) (2007) 34-36.
[9]  A. Khalifeh, A.D. Banaraki, H.D. Manesh, M.D. Banaraki, Investigating of the tensile mechanical properties of structural steels at high strain rates, Materials Science and Engineering: A, 712 (2018) 232-239.
[10] U. Olofsson, T. Telliskivi, Wear, plastic deformation and friction of two rail steels—a full-scale test and a laboratory study, Wear, 254(1-2) (2003) 80-93.
[11] D. Ye, Z. Wang, An approach to investigate prenucleation fatigue damage of cyclically loaded metals using Vickers microhardness tests, International journal of fatigue, 23(1) (2001) 85-91.
[12] J. Lemaitre, J. Dufailly, R. Billardon, Evaluation de l’endommagement par mesures de microdureté, Comptes rendus de l’Académie des sciences. Série 2, Mécanique, Physique, Chimie, Sciences de l’univers, Sciences de la Terre, 304(12) (1987) 601-604.
[13] A. Mkaddem, F. Gassara, R. Hambli, A new procedure using the microhardness technique for sheet material damage characterisation, Journal of Materials Processing Technology, 178(1-3) (2006) 111-118.
[14] Z. Zhang, M. Hauge, J. Ødegård, C. Thaulow, Determining material true stress–strain curve from tensile specimens with rectangular cross-section, International Journal of Solids and Structures, 36(23) (1999) 3497-3516.
[15] S.-Y. Yang, W. Tong, A finite element analysis of a tapered flat sheet tensile specimen, Experimental mechanics, 49(2) (2009) 317-330.
[16] J. Choung, S. Cho, Study on true stress correction from tensile tests, Journal of Mechanical Science and Technology, 22(6) (2008) 1039-1051.
[17] A.A.S.f. Testing, Materials, Standard test methods for tension testing of metallic materials, ASTM international, 2009.
[18] B. N, nonlinear CDM model for ductil failure Eng Fract Mech,  (1981) 58:11–52.
[19] J. Lemaitre, A continuous damage mechanics model for ductile fracture, Journal of engineering materials and technology, 107(1) (1985) 83-89.
Amirkabir Journal of Mechanical Engineering
Volume 52, Issue 3
June 2020
Pages 647-656

Files

Share

How to cite

Statistics