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1.
The behavior of hydrogen induced slow crack growth in type 310 and type 16-20-10 stable austenitic stainless steels along
with type 321 unstable austenitic stainless steel were investigated. It was found that slow crack growth could occur in all
three types of stainless steels, and the threshold values wereK
H/Kc = 0.55, 0.7, and 0.78 for type 321, 310, and 16-20-10 stainless steel respectively, when charged under load. Slow crack growth
could also occur if the precharged specimens were tested under constant load in air. No slow crack growth occurred in the
precharged and then out-gassed specimens. This indicates that delayed cracking in stable austenitic stainless steels is induced
by hydrogen. Since there is no hydrogen induced α’ martensite in type 310 and 16-20-10 stainless steel, the existence of a’
martensite is not necessary for the occurrence of slow crack growth in the austenitic stainless steels, although it can facilitate
slow crack growth. The mode of hydrogen induced delayed fracture in either the stable or unstable austenitic stainless steel
is correlated with theK, value; the fracture surface is changed from ductile to brittle asK
1 is decreased. 相似文献
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Because of their high corrosion resistance and deformation characteristics, the industrial application of stainless steels is of high importance. During deep drawing processes, phase transformation of austenite to martensite occurs, which leads to an increased strain hardening of the material. The phase transformation depends on alloying constituents, transformation temperatures, stresses and strains. Consequently, in the design of deep drawing processes of stainless steels the phase transformation has to be considered. This paper presents a mathematical model for the calculation of the martensite evolution depending on temperatures, stresses and strains. The precise simulation of deep drawing processes of stainless steels can be enabled by the implementation of this model into commercial FE‐programs. 相似文献
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Dai Kaiju Wang Bo Xue Fei Liu Shanshan Huang Junkai Zhang Jieyu 《Metallurgical and Materials Transactions B》2018,49(4):2011-2021
Metallurgical and Materials Transactions B - The nucleation and growth of nitrogen bubbles for duplex stainless steels are of great significance for the formation mechanism of bubbles during... 相似文献
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The Formation of Martensitic Austenite During Nitridation of Martensitic and Duplex Stainless Steels
Amirali Zangiabadi John C. Dalton Danqi Wang Frank Ernst Arthur H. Heuer 《Metallurgical and Materials Transactions A》2017,48(1):8-13
Isothermal martensite/ferrite-to-austenite phase transformations have been observed after low-temperature nitridation in the martensite and \(\updelta \)-ferrite phases in 15-5 PH (precipitation hardening), 17-7 PH, and 2205 (duplex) stainless steels. These transformations, in the region with nitrogen concentrations of 8 to 16 at. pct, are consistent with the notion that nitrogen is a strong austenite stabilizer and substitutional diffusion is effectively frozen at the paraequilibrium temperatures of our experiments. Our microstructural and diffraction analyses provide conclusive evidence for the martensitic nature of these phase transformations. 相似文献
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Ridging Control in Transformable Ferritic Stainless Steels 总被引:1,自引:0,他引:1
Javad Mola Ilchan Jung Jieon Park Dongchul Chae Bruno C. de Cooman 《Metallurgical and Materials Transactions A》2012,43(1):228-244
An alloy design concept leading to an improved ridging resistance in the transformable ferritic stainless steels is introduced. It is based on achieving a small γ-phase fraction at the ingot soaking temperature. The γ-phase fraction is then increased to a maximum value during the early stages of hot rolling. The nucleation of γ-phase islands in the ferritic matrix increases the fraction of transformed ferrite. The multiplicity of crystallographic orientations resulting from the α→γ and γ→α transformations leads to a pronounced weakening of the as-cast texture and an increased ridging resistance. 相似文献
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Impact toughness testing was conducted on 10 and 30 mm plates of 2205 together with a 30 mm plate of LDX 2101® duplex stainless steel (DSS). The testing temperatures were between 153 K (?120 °C) and room temperature. Interrupted fracture toughness tests of the 10 mm plate and a 50 mm plate of 2205 were also performed. The conclusion from the fractographic investigation was that the delaminations that occur in hot-rolled DSSs were cleavage fractures. The toughness anisotropy can be explained by the cleavage fracture and the appearance of the microstructure. The result from the interrupted fracture toughness test revealed that the delaminations initiated prior to the maximum force plateau and propagated ahead of the stable crack growth during testing. Estimated upper limit for the fracture delamination initiation toughness at sub-zero temperatures for the 2205 base metal according to the crack-tip opening displacement method was 28 to 61 μm for the 10 mm plate, 70 to 106 μm for the 30 mm plate and below 100 μm for the 50 mm plate. 相似文献
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《Canadian Metallurgical Quarterly》2013,52(4):483-491
AbstractThe results of some investigations on the stabilization of austenite by hydrogen in two tool steels are reported in this paper. It is shown that hydrogen stabilizes the austenite if introduced cathodically at appropriate stage. Cathodic impregnation is shown to be essential for such stabilization. It has also been shown that the quantity of hydrogen required for stabilizing the austenite need not be large, if the manner of its introduction into the austenite prior to transformation is appropriate. Résumé Nous présentons ici les résultats des quelques recherches sur la stabilisation de l'austénite par l'hydrogène dans deux aciers à outils. Il est montré que l'hydrogène stabilise l'austénite s'il est introduit cathodiquement à un stade approprié. Et l'on montre que l'imprégnation cathodique est essentielle à une telle stabilisation. On a également montré que la quantité d'hydrogène requise pour stabiliser l'austénite n'a pas besoin d'être importante, si la façon dont elle a été introduite dans l'austénite avant transformation est appropriée. 相似文献
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Srinivasan N. Sunil Kumar B. Kain V. Birbilis N. Joshi S. S. Sivaprasad P. V. Chai G. Durgaprasad A. Bhattacharya S. Samajdar I. 《Metallurgical and Materials Transactions A》2018,49(6):2281-2292
Metallurgical and Materials Transactions A - Austenitic stainless steels grades, with differences in chemistry, stacking fault energy, and thermal conductivity, were subjected to vertical milling.... 相似文献
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Yucel Birol Duygu İsler Mustafa Urgen 《Metallurgical and Materials Transactions A》2011,42(11):3316-3322
Thin hard coatings provide the much needed protection for steel thixoforming tools that must resist wear at high temperatures.
The wear resistance of AlTiN- and AlTiON-coated hot work tool steel was investigated at 1023 K (750 °C), measured to be the
cavity surface temperature shortly after the steel slurry was forced into the thixoforming die. The wear tests were repeated
in exactly the same fashion with uncoated tool steel samples to identify the impact of AlTiN and AlTiON coatings on the high-temperature
wear performance of X32CrMoV33 tool steel. The nature, the thickness, and the adherence of the oxide scales impact the tribological
behavior. The poor adherence and limited ductility of ferrous oxides promote the failure of the oxide scale impairing the
resistance to wear of the hot work tool steel at elevated temperatures. The substantial softening in the X32CrMoV33 hot work
tool steel is also critical in the wear volume loss it suffers. AlTiN and AlTiON coatings, on the other hand, form a stable
and protective oxide surface layer at high temperatures and therefore provide an enhanced resistance to oxidation. The latter
is relatively more resistant to oxidation and is thus the better of the two coatings tested in the present work. 相似文献
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X. H. Zeng P. Xue D. Wang D. R. Ni B. L. Xiao Z. Y. Ma 《Metallurgical and Materials Transactions A》2018,49(7):2673-2683
The effect of processing parameters on material flow and defect formation during friction stir welding (FSW) was investigated on 6.0-mm-thick 2014Al-T6 rolled plates with an artificially thickened oxide layer on the butt surface as the marker material. It was found that the “S” line in the stir zone (SZ) rotated with the pin and stayed on the retreating side (RS) and advancing side (AS) at low and high heat inputs, respectively. When the tool rotation rate was extremely low, the oxide layer under the pin moved to the RS first and then to the AS perpendicular to the welding direction, rather than rotating with the pin. The material flow was driven by the shear stresses produced by the forces at the pin–workpiece interface. With increases of the rotation rate, the depth of the shoulder-affected zone (SAZ) first decreased and then increased due to the decreasing shoulder friction force and increasing heat input. Insufficient material flow appeared in the whole of the SZ at low rotation rates and in the bottom of the SZ at high rotation rates, resulting in the formation of the “S” line. The extremely inadequate material flow is the reason for the lack of penetration and the kissing bonds in the bottom of the SZ at extremely low and low rotation rates, respectively. 相似文献
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Hertzman Staffan Naraghi Reza Wessman Sten Pettersson Rachel Borggren Ulrika Jonsson Jan Y. Pettersson Niklas Holländer Karami Mina Khoda Kohan-Zade Ali 《Metallurgical and Materials Transactions A》2021,52(9):3811-3820
Metallurgical and Materials Transactions A - High-performance stainless steels are alloyed with nitrogen for several different reasons. For the austenitic grades, the kinetics of deleterious phase... 相似文献
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Mertcan Başkan Scott L. Chumbley Yunus Eren Kalay 《Metallurgical and Materials Transactions A》2014,45(5):2405-2411
Superaustenitic stainless steels (SSS) are widely used in extreme environments such as off-shore oil wells, chemical and food processing equipment, and seawater systems due to their excellent corrosion resistance and superior toughness. The design of the corresponding heat treatment process is crucial to create better mechanical properties. In this respect, the short-term annealing behavior of CN3MN grade SSS was investigated by a combined study of Charpy impact tests, hardness measurements, scanning and transmission electron microscopy. Specimens were heat treated at 1200 K (927 °C) for up to 16 minutes annealing time and their impact strengths and hardnesses were tested. The impact toughness was found to decrease to less than the half of the initial values while hardness stayed the same. Detailed fracture surface analyses revealed a ductile to brittle failure transition for relatively short annealing times. Brittle fracture occurred in both intergranular and transgranular modes. SEM and TEM indicated precipitation of nano-sized intermetallics, accounting for the intergranular embrittlement, along the grain boundaries with respect to annealing time. The transgranular fracture originated from linear defects seen to exist within the grains. Close observation of such defects revealed stacking-fault type imperfections, which lead to step-like cracking observed in microlength scales. 相似文献
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Hamid Azizi-Alizamini Matthias Militzer Warren J. Poole 《Metallurgical and Materials Transactions A》2011,42(6):1544-1557
In this study, austenite formation from hot-rolled (HR) and cold-rolled (CR) ferrite-pearlite structures in a plain low-carbon steel was investigated using dilation data and microstructural analysis. Different stages of microstructural evolution during heating of the HR and CR samples were investigated. These stages include austenite formation from pearlite colonies, ferrite-to-austenite transformation, and final carbide dissolution. In the CR samples, recrystallization of deformed ferrite and spheroidization of pearlite lamellae before transformation were evident at low heating rates. An increase in heating rate resulted in a delay in spheroidization of cementite lamellae and in recrystallization of ferrite grains in the CR steel. Furthermore, a morphological transition is observed during austenitization in both HR and CR samples with increasing heating rate. In HR samples, a change from blocky austenite grains to a fine network of these grains along ferrite grain boundaries occurs. In the CR samples, austenite formation changes from a random spatial distribution to a banded morphology. 相似文献
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In microalloyed steels, static recrystallisation is temporarily inhibited by precipitation which is occurring at the same time. A high number of microalloyed steels containing various combinations of carbon, nitrogen and precipitate forming elements like V, Nb and Ti were recrystallised at different temperatures and strain rates. From these results recrystallisation‐precipitation–time‐temperature (RPTT) diagrams were established. The influence of grain size and strain rate on the RPTT diagrams was studied. The precipitation kinetics were mathematically described for isothermal conditions and converted to cooling conditions, which enables an application to hot rolling. Under cooling conditions, completion of recrystallisation is prevented, especially for Nb alloyed steels. 相似文献