Fracture is the ultimate continuum of a material. Hence, it is possible that the fracture features contain the signature of the whole deformation process undergone due to variation in triaxial state of stress under tensile deformation. The two dimensional fracture features were correlated with the stress triaxiality ratio where initial inclusion content was unaltered. In order to test that, many tensile experiments of a superalloy were carried out at different notch geometries and fractographic investigation was done extensively to correlate the fracture features (ie., fractured grain size, extent of tearing ridge, dimple diameter and dimple number density) with the tensile properties.
#1Arpan Das(CSIR: Council of Scientific and Industrial Research)H-Index: 19
#2Nilima Roy(CSIR: Council of Scientific and Industrial Research)H-Index: 14
Last. Ashok Kumar Ray(CSIR: Council of Scientific and Industrial Research)H-Index: 4
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Studies monitoring cavity nucleation with strain after creep deformation has limited information with varying applied stresses. In the present communication, a large number of experiments were performed to investigate cavity nucleation at different stresses for a primary reformer tube. It has been found that with the increase in stress, cavity formation increases drastically, which is more prone to nucleate at grain boundary triple junctions rather than grain boundaries where the extent of initi...
#1Nilima Roy(CSIR: Council of Scientific and Industrial Research)H-Index: 14
#2Arpan Das(CSIR: Council of Scientific and Industrial Research)H-Index: 19
Last. Ashok K Ray(CSIR: Council of Scientific and Industrial Research)H-Index: 21
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Abstract In this paper creep damage assessment of 12 years service exposed HP-40 grade of steel used in hydrogen reformer of a petrochemical industry has been carried out in terms of a discontinuous Markov process. Experimentally determined conventional creep data under identical testing condition were used in the present investigation. The occurrences of damage and its accumulation due to creep deformation were evaluated through microstructural assessment using light optical microscope and scan...
Abstract This communication reports the effects of microstructure and temperature on Crussard–Jaoul work hardening coefficient, n, in service aged Alloy 625. Microstructure containing fine precipitates exhibited high values of n while that containing coarse particles exhibited low n. These results are explained on the basis of ordered structure of precipitate particles.
#1Arpan Das(CSIR: Council of Scientific and Industrial Research)H-Index: 19
#2Palash Poddar(CSIR: Council of Scientific and Industrial Research)H-Index: 10
Wear is the loss of dimension through plastic deformation, which originates at interfaces between two sliding surfaces. Hence, it is logical to correlate the worn surface features and their morphologies with the resulting wear properties. The two dimensional extent of such wear damage accumulations (i.e., impressions of ploughing lines along with adhered debris fraction), quantified from the worn surface fractographs are observed to predict the nature of the variation in the wear properties with...
#1Arpan Das(CSIR: Council of Scientific and Industrial Research)H-Index: 19
The interaction between deformation-induced martensite and voids has been quantitatively established during the tensile deformation of metastable austenitic stainless steel at various strain rates under ambient temperature where the initial inclusion volume fraction was kept constant. The inhomogeneous distribution of deformation-induced martensite under tension influences void nucleation and growth, and hence keeps imprint on dimple geometries on fracture surfaces.
#1Arpan Das(CSIR: Council of Scientific and Industrial Research)H-Index: 19
#2S. Sivaprasad(CSIR: Council of Scientific and Industrial Research)H-Index: 21
Last. Soumitra Tarafder(CSIR: Council of Scientific and Industrial Research)H-Index: 26
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Damage is controlled by the chemistry of the material, initial inclusions or second phase particles' fractions with their size/shape distribution, stress triaxility, strain, stress, strain rate, strain path, grain size, initial crystallographic micro-texture and the temperature of deformation. In this study, a model has been developed to correlate the complex relationship between the extent of damage accumulations (i.e., void area fraction) with its influencing parameters in a variety of high st...
#1Arpan Das(CSIR: Council of Scientific and Industrial Research)H-Index: 19
#2Samar Das(CSIR: Council of Scientific and Industrial Research)H-Index: 8
Last. Soumitra Tarafder(CSIR: Council of Scientific and Industrial Research)H-Index: 26
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In continuum damage mechanics approach, damage accumulation takes place through void nucleation, void growth and void coalescence. Damage accumulation is influenced by the chemical compositions of the alloy, initial inclusions content and their distribution, stress triaxility, strain, stress, strain rate, grain size, initial micro-texture and temperature of deformation. In this study, a neural network based model has been created to analyse the complex correlation between the damage accumulation...
A two-layer structure composite, in which one layer was B4C/Al compound and the other layer was B4C/ TiB2 compound, was prepared using a two-step method for both hot pressing and infiltration of aluminum in vacuum. The experimental results showed that the two-layer B4C/Al-B4C/TiB2 composite having good interfacial bonding was prepared. Before aluminum infiltration process, the B4C porous layer of the two-layer preform looked like a three-dimensional network of interconnected capillaries that cou...
#2J. B. Singh(BARC: Bhabha Atomic Research Centre)H-Index: 9
The present study examined the evolution of microstructure and mechanical properties of Alloy 625 ammonia cracker tubes of heavy water production plant which had been exposed to temperatures around 600°C for 100 000 h. Detailed investigations revealed considerable modification of microstructure, significant increase of strength and loss of ductility and toughness during service and the extent of degradations were found to be sensitive to service temperature at different locations of the tube. Wh...
Austenitic stainless steels, such as AISI 304LN, are candidate materials for structural applications in many critical components, including for heat transport piping of nuclear power plants. The design of such components requires a thorough understanding of the deformation behaviour, fracture mechanisms and phase transformation characteristics of the construction material. Metastable austenitic stainless steels, like AISI 304LN stainless steel undergo deformation induced martensitic transformati...
#1Arpan Das(BARC: Bhabha Atomic Research Centre)H-Index: 19
Flow stress during hot deformation is essentially controlled by the chemistry of material, initial microstructure/texture, strain, strain rate, strain path, stress triaxility and the temperature of deformation. A comprehensive literature survey has been performed to realize this fact completely. In the present research, a neural network model under Bayesian framework has been created to correlate the complex relationship between flow stress with its influencing parameters in various grades of zi...
The notch sensitivity of additively manufactured IN 625 superalloy produces by laser powder bed fusion (LPBF) has been investigated by tensile testing of cylindrical test pieces. Smooth and V-notched test pieces with four different radii were tested both in as-built state and after a stress relief heat treatment for 1 h at 900 °C. Regardless of the notch root radius, the investigated alloy exhibits notch strength ratios higher than unity in both as-built and in stress-relieved states, showing th...
Abstract The effects of short notches on crack initiation and extension were studied under electrochemical hydrogen charging in pure nickel. In the hydrogen-charged smooth specimen, multiple cracks were initiated on grain boundaries after significant plastic deformation and were subsequently arrested by crack blunting in the interior of neighboring grains. With the assistance of sub-cracks on specimen surface, quasi-cleavage crack propagation occurred soon after, causing the final failure. The i...
#1Mao Jianfeng(Zhejiang University of Technology)H-Index: 1
#2Xiangyang Li(Zhejiang University of Technology)H-Index: 3
Last. Yan Ling(Zhejiang University of Technology)H-Index: 1
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Abstract In this paper, the multi-axial creep behavior of Inconel 783 at 700 °C is studied. The stress triaxiality was introduced for the specimen by adding a circumferential notch with different acuity ratios. In order to study the influence of the notch ratios on creep ductility and damage evolution of Inconel 783, the Gurson-Tvergaard-Needleman (GTN model) is adopted in numerical simulation for investigating the multiaxial failure of the notched bar. Actually, the micro-observation is also em...
#1Łukasz Derpeński(Bialystok University of Technology)H-Index: 4
The paper presents an experimental investigation of the ductile fracture of specimens with different circumferential notches. Specimens made from ENAW_2024-T351 aluminum alloy were subjected to non-proportional tension–torsion loading. The tests were carried out on an MTS testing machine coupled with the ARAMIS 3D 4M vision measuring system, enabling simultaneous non-contact tracking of the elongation and torsional angle of the measurement base. Depending on the assumed notch radius and the non-...
The field of rock mechanics is concerned with the response of rocks to the forces acting on them, characterizing this behaviour in specific environments and under varying loading conditions. This review discusses the suitability of current mechanical testing methods for inhomogeneous rock bodies, with a specific focus on the use of artificial samples in place of real rocks in these tests. The use of artificial materials such as cement, resins, and sand-based mixtures is reviewed, as is the manuf...
#1Arpan Das(BARC: Bhabha Atomic Research Centre)H-Index: 19
#2C.B. Basak(BARC: Bhabha Atomic Research Centre)H-Index: 16
Fracture surface retains an of the entire deformation history undergone in a material. Hence, it is possible to derive the approximate deformation and fracture properties of a material from a syste...
Fatigue is one of the main reasons of fracture in mechanical components. Generally performing experiments is a useful and effective method for determination of fatigue life. In this paper, results of different notch geometry effects on the fatigue life under mixed mode I and III were studied experimentally and numerically. For this purpose, fatigue specimens were manufactured according to the ASTM-A370 standard and all the specimens were quenched and tempered. Two types of notch geometries, V-sh...
Abstract Duplex stainless steels are characterized by oriented microstructures, in which its constituent phases, ferrite ( α ) and austenite ( γ ) form layered or fibrous phase arrangements depending on forming operations (e.g. rolling). These microstructures have the potential to induce anisotropy in the macroscopic mechanical properties of the material. A very interesting phenomenon related to this microstructurally-induced anisotropy is the subject of investigation in the present work: a samp...
#1G. Sanyal(BARC: Bhabha Atomic Research Centre)H-Index: 9
Abstract Structural integrity of the core components of the nuclear reactors is vital for steady economical operation and avoidance of unwanted disasters. Two new test methods have been developed for quantifying the resistance to axial cracking of thin-walled tubular specimens. The specimens are fabricated from cladding tubes made of austenitic stainless steel for Indian fast breeder reactors. The reproducibility of the fracture toughness test results using the developed setups yields promising ...
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