Neutron Diffraction Experiments to Identify Internal State Created by Forward Creep in Austenitic Stainless Steel at 550 C (original) (raw)
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Deformation Behavior of An Austenitic Steel by Neutron Diffraction
Proceedings of the 12th Asia Pacific Physics Conference (APPC12), 2014
An austenitic stainless steel type 304, which is one of the most popular materials in use, was tensile deformed and in situ neutron diffraction measurement was performed. The neutron diffraction measurement was conducted using an engineering materials diffractometer installed at MLF/J-PARC. Because of the combination of the high neutron intensity, the high counting rate and an event data recording method, in situ neutron diffraction during tensile loading at plastic deformation could be performed without any interruption for load or displacement. Intergranular strains and bulky stress observed during deformation were discussed on the crystal orientation dependence.
Internal strains between grains during creep deformation of an austenitic stainless steel
Journal of Materials Science
Internal strains that develop between grains during creep of an austenitic stainless steel were measured using in situ neutron diffraction. The secondary creep prestrained test specimens were considered. Measurements were undertaken before, during and post creep deformation at 550 �C. There was no measurable change of internal strains between grains during in situ creep for 4 h at 550 �C. In addition, the effect of increasing/reducing temperatures in a range from 470 to 550 �C on the internal strains was measured and interpreted with respect to contributions from thermal expansion/contraction. No further internal misfit strains between grains were created when specimen crept during the dwell time at 530, 510, 490 and 470 �C. Results are discussed with respect to (i) the general structure of self-consistent models and (ii) the optimised use of neutron sources for creep studies.
Journal of Applied Crystallography, 2011
Owing to its selectivity, diffraction is a powerful tool for analysing the mechanical behaviour of polycrystalline materials at the mesoscale (phase and/ or grain scale). In situ neutron diffraction during tensile tests and elastoplastic self-consistent modelling were used to study slip phenomena occurring on crystallographic planes at small and large deformation. The critical resolved shear stresses in both phases of duplex stainless steel were found for samples subjected to different thermal treatments. The evolution of grain loading was also determined by showing the large differences between stress concentration for grains in ferritic and austenitic phases. It was found that, for small loads applied to the sample, linear elastic deformation occurs in both phases. When the load increases, austenite starts to deform plastically, while ferrite remains in the elastic range. Finally, both phases undergo plastic deformation until sample fracture. By using an original calibration of diffraction data, the range of the study was extended to large sample deformation. As a result, mechanical effects that can be attributed to damage processes initiated in ferrite were observed. research papers J. Appl. Cryst. (2011). 44, 966-982 A. Baczmanski et al. Aged duplex stainless steel under deformation 967 research papers J. Appl. Cryst. (2011). 44, 966-982 A. Baczmanski et al. Aged duplex stainless steel under deformation 977 Figure 11
Neutron Diffraction Study of Fatigue Behaviors in 316LN Stainless Steel
Journal of Neutron Research, 2004
Time-of-flight neutron diffraction has been used to investigate deformation behaviors due to cyclic loading. A study of 316LN .slainless steel shows that in ihe early stage of fatigue life, grain-orientation dependent intergranular stresses develop quickly and oscillate between two extreme states corresponding to the ends of a tensile or compressive half loading cycle. In the late slage. the intergranular strains vanish for tests ending in tension and remain relatively unchanged for tests ending in compression, which poinis to the difference in plastic behaviors during tensile and compressive loadings.
ISIJ International, 2013
To investigate the tensile deformation behavior of a lean duplex stainless steel (S32101) from the viewpoints of plastic deformability among phases or grains, we performed static tensile tests, in situ neutron diffraction, and white x-ray diffraction experiments at room temperature. In the static tensile tests, the S32101 steel displayed a larger uniform elongation and a better tensile strength-uniform elongation balance than a commercial SUS329J4L duplex stainless steel. A larger uniform elongation of S32101 is associated with the macroscopic work hardening behavior that a work hardening rate higher than the flow stress can maintain up until high true strains. From the experimental results of synchrotron radiation white x-ray diffraction experiments, the hard phase of S32101 was changed from the ferrite (α) phase to austenite (γ) one during tensile deformation. This led to a larger stress partitioning between the phases at the latter stage of deformation. From the experimental results of in situ neutron diffraction, it was found that the stress partitioning of the γ phase in the S32101 was the largest among the present results. Therefore, the larger work hardening rate of S32101 can be explained by the large stress partitioning of the γ phase, that between γ and α phases and γ volume fraction.
Applied Physics A: Materials Science & Processing, 2002
The fatigue behaviour of austenitic stainless steel, in which a martensitic phase is formed due to plastic deformation, is of some interest for practical reasons. Earlier, we reported the results of the first stage of the in situ stressrig experiment on the ENGIN instrument at the ISIS facility, with samples from steel X6CrNiTi1810 subjected to different tensile-compressive loading cycles at a frequency of 5 Hz. This paper describes the results of the second stage of the experiment in which a series of samples subjected to 0.5 Hz was studied. Information about the mechanical properties of the austenitic matrix and the martensitic precipitates is obtained from the experimental mechanical and neutron-diffraction
ISIJ International, 2021
In situ neutron diffraction experiments during tensile deformation were conducted to investigate the effect of temperature on the tensile properties of JIS-SUS316L steel from the phase stresses of austenite (γ) and ferrite (α) phases and the kinetics of deformation-induced martensitic transformation (DIMT). The 0.2% proof stress and tensile strength increased with decreasing deformation temperature, and the maximum uniform elongation was reached at 223 K. The temperature of the maximum uniform elongation in metastable austenitic stainless steels is related to the mechanical stability of γ and showed good correlation with the Ni equivalent. The estimated phase stress of γ at a given true strain increased with decreasing temperature; however, the temperature dependence of the twinning-induced plasticity effect of the γ phase was small. The phase stress of α was almost independent of temperature between 138 K and 223 K. The effect of temperature on the mechanical properties of the SUS316L steel was largely affected by the transformation-induced plasticity effect, which was related to the kinetics of DIMT according to in situ neutron diffraction experiments.
Microstructure Evolution During Creep of Cold Worked Austenitic Stainless Steel
IOP Conference Series: Materials Science and Engineering, 2018
The 14Cr-15Ni austenitic stainless steel (SS) with additions of Ti, Si, and P has been developed for their superior creep strength and better resistance to void swelling during service as nuclear fuel clad and wrapper material. Cold working induces defects such as dislocations that interact with point defects generated by neutron irradiation and facilitates recombination to make the material more resistant to void swelling. In present investigation, creep properties of the SS in mill annealed condition (CW0) and 40 % cold worked (CW4) condition were studied. D9I stainless steel was solution treated at 1333 K for 30 minutes followed by cold rolling. Uniaxial creep tests were performed at 973 K for various stress levels ranging from 175-225 MPa. CW4 samples exhibited better creep resistance as compared to CW0 samples. During creep exposure, cold worked material exhibited phenomena of recovery and recrystallization wherein new strain free grains were observed with lesser dislocation network. In contrast CW0 samples showed no signs of recovery and recrystallization after creep exposure. Partial recrystallization on creep exposure led to higher drop in hardness in cold worked sample as compared to that in mill annealed sample. Accelerated precipitation of carbides at the grain boundaries was observed during creep exposure and this phenomenon was more pronounced in cold worked sample.