Abstract:Uniaxial tensile tests were conducted on AISI 316LN austenitic stainless steel from-40C to 300C at a rate of 0.5 mm/min. Microstructure and mechanical properties of the deformed steel were investigated by optical, scanning and transmission electron microscopies, X-ray diffraction, and microhardness testing. The yield strength, ultimate tensile strength, elongation and microhardness increase with the decrease of the test temperature. The tensile fracture morphology has the dimple rupture feature after low tem… Show more
“…The amount of deformation-induced martensite depends on the chemical composition [2,116,117], initial grain size [73,85,[117][118][119][120][121][122][123][124][125][126][127][128], deformation temperature [56,57,[129][130][131][132][133][134][135], strain rate [57,[136][137][138][139][140][141][142], stress state and strain state [57,137,[143][144][145][146][147][148][149], strain [150][151][152], applied magnetic field [153], etc. Among these parameters, the chemical composition and initial grain size of the austenite phase can be classified as the material factors while the rest of parameters are deform...…”
Section: Factors Affecting the Transformation Kineticsmentioning
Recent progress in the understanding of the deformation-induced martensitic transformation, the transformation-induced plasticity (TRIP) effect, and the reversion annealing in the metastable austenitic stainless steels are reviewed in the present work. For this purpose, the introduced methods for the measurement of martensite content are summarized. Moreover, the austenite stability as the key factor for controlling the austenite to martensite transformation is critically discussed. This is realized by analyzing the effects of chemical composition, initial grain size, applied strain, deformation temperature, strain rate, and deformation mode (stress state). For instance, the effect of initial grain size is found to be complicated, especially in the ultrafine grained (UFG) regime. Furthermore, it seems that there is a critical grain size for changing the trend of α′-martensite formation. Decreasing the deformation temperature motivates the formation of α′-martensite, but there is a critical temperature for achieving the maximum tensile ductility. Afterwards, the modeling techniques for the transformation kinetics and the contribution of deformation-induced martensitic transformation to the strengthening of material and also strength-ductility trade-off are critically surveyed. The processing of UFG microstructure during reversion annealing, the effects of the recrystallization of the retained austenite, the martensitic shear and diffusional reversion mechanisms, and the annealing-induced martensitic transformation are also summarized. Accordingly, this overview presents the opportunities that the strain-induced martensitic transformation can offer for controlling the microstructure and mechanical properties of metastable austenitic stainless steels.
“…The amount of deformation-induced martensite depends on the chemical composition [2,116,117], initial grain size [73,85,[117][118][119][120][121][122][123][124][125][126][127][128], deformation temperature [56,57,[129][130][131][132][133][134][135], strain rate [57,[136][137][138][139][140][141][142], stress state and strain state [57,137,[143][144][145][146][147][148][149], strain [150][151][152], applied magnetic field [153], etc. Among these parameters, the chemical composition and initial grain size of the austenite phase can be classified as the material factors while the rest of parameters are deform...…”
Section: Factors Affecting the Transformation Kineticsmentioning
Recent progress in the understanding of the deformation-induced martensitic transformation, the transformation-induced plasticity (TRIP) effect, and the reversion annealing in the metastable austenitic stainless steels are reviewed in the present work. For this purpose, the introduced methods for the measurement of martensite content are summarized. Moreover, the austenite stability as the key factor for controlling the austenite to martensite transformation is critically discussed. This is realized by analyzing the effects of chemical composition, initial grain size, applied strain, deformation temperature, strain rate, and deformation mode (stress state). For instance, the effect of initial grain size is found to be complicated, especially in the ultrafine grained (UFG) regime. Furthermore, it seems that there is a critical grain size for changing the trend of α′-martensite formation. Decreasing the deformation temperature motivates the formation of α′-martensite, but there is a critical temperature for achieving the maximum tensile ductility. Afterwards, the modeling techniques for the transformation kinetics and the contribution of deformation-induced martensitic transformation to the strengthening of material and also strength-ductility trade-off are critically surveyed. The processing of UFG microstructure during reversion annealing, the effects of the recrystallization of the retained austenite, the martensitic shear and diffusional reversion mechanisms, and the annealing-induced martensitic transformation are also summarized. Accordingly, this overview presents the opportunities that the strain-induced martensitic transformation can offer for controlling the microstructure and mechanical properties of metastable austenitic stainless steels.
“… Figure 8 Yield stress of AISI 316 grade austenitic stainless steels and model composition used in MD simulations as function of temperature. Experimental measurements are from references: ( a ) 77 , ( b ) 78 , ( c ) 79 , ( d ) 80 , ( e ) 81 . Ref.…”
A new mechanism for controlling the microstructure of products in manufacturing processes based on selective laser melting is proposed. The mechanism relies on generation of high-intensity ultrasonic waves in the melt pool by complex intensity-modulated laser irradiation. The experimental study and numerical modeling suggest that this control mechanism is technically feasible and can be effectively integrated into the design of modern selective laser melting machines.
“…It is known that in order to provide a high resistance to hot cracking, the deposited metal must not be completely austenitic but have a structure consisting of austenite and a proportion of 4 -12 % ferrite δ [19][20]. Hardness measurements The intensity of the microstructural changes produced in the coating-substrate system, shown in figure 3, was evaluated by microhardness measurements, HV0.05.…”
Section: Evaluation and Interpretation Of The Experimental Results MImentioning
confidence: 99%
“…The degradation and the removal of the material is produced by fatigue break mechanism; at the bottom of the holes caused by the graphite separation, one can observe the presence of some micro tunnels ( fig. 10) [19,20].…”
Section: Surface Topography and Microstructure Of Cavitation Eroded Cmentioning
Stainless steel 316L coating was high velocity oxygen fuel (HVOF) sprayed onto the surface of nodular cast iron in order to improve its surface properties in terms of corrosion and cavitation resistance. The cavitation resistance and corrosion behaviour of the nodular cast iron was investigated before and after coating deposition. The morphology and microstructure of the samples was analysed by optical and scanning electron microscopy (SEM) and X-ray diffraction technique (XRD). The cavitation measurements were carried out on a standard vibrator device. They have been correlated with the microhardness and surface roughness measurements. The corrosion evaluation was made by electrochemical tests. The results showed enhanced values in cavitation resistance of approx. 2.7 times and a decreasing of the corrosion rate for the coated cast iron.
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