共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
A. B. Rozhnov S. A. Nikulin I. V. Shchetinin S. L. Shitkin S. O. Rogachev 《Russian Metallurgy (Metally)》2017,2017(5):384-389
Surface stresses in samples of wheel steel with different degree of plastic deformation are studied. Both surface stresses and the microstructure of the steel are changed in the dependence on the plastic deformation magnitude. The X-ray technique is shown can be used to study a change in the surface stresses due to development a plastic deformation under action of operating loads. 相似文献
3.
Brager H. R. Straalsund J. L. Holmes J. J. Bates J. F. 《Metallurgical and Materials Transactions B》1971,2(7):1893-1904
Metallurgical and Materials Transactions B - The microstructure of annealed AISI Type 304 and type 316 stainless steels has been characterized by transmission electron microscopy as a function of... 相似文献
4.
We report in this paper a study of surface segregation in austenitic stainless steel. Auger electron spectroscopy was used
to measure segregation as a function of time and temperature. We have found that P, N, S, Cr, and Ni will all segregate to
the surface. However, their presence on the surface often depends on the competitive and attractive interactions between the
various elements. We show that thermodynamic data on ternary liquid iron alloys are quite valuable in predicting these interactions.
We also discuss possible applications of these studies. 相似文献
5.
Carburization of austenitic stainless steels under paraequilibrium conditions—i.e., at (low) temperatures where there is essentially no substitutional diffusion—leads to a family of steels with remarkable properties: enhanced hardness, resulting in improved wear behavior, enhanced fatigue, and corrosion resistance, and with essentially no loss in ductility. These enhanced properties arise from an enormous carbon solubility, which, absent carbide formation, is orders of magnitude greater than the equilibrium solubility. Using interaction parameters from the latest CALPHAD assessment of the Fe-Cr-Ni-carbon system, the authors have calculated the equilibrium and paraequilibrium carbon solubility in a model Fe-18Cr-12 Ni (wt pct) austenitic steel (essentially a model 316L composition), as well as the carbon solubility in this austenite when paraequilibrium carbide formation occurs (i.e., when carbides form in a partitionless manner). For temperatures in the range 725 to 750 K, the calculations predict a paraequilibrium carbon solubility of ~5.5 at. pct. Carburization of 316L stainless steel at these temperatures, however, results in significantly higher concentrations of carbon in solid solution—up to 12 at. pct. Much better agreement with experimental data is obtained by calculating the paraequilibrium carbon solubility using Wagner interaction parameters, taken from the most comprehensive experimental study of this system. The discrepancy between the two predicted solubilities arises because the CALPHAD Cr-carbon interaction parameters are not sufficiently exothermic at the low temperatures used for paraequilibrium carburization. After multiple paraequilibrium carburization cycles, carbide formation can occur. The carbides that form under these conditions do so in a near-partitionless manner (there is modest Ni rejection to the austenite/carbide interface) and have an unusual stoichiometry: M5C2 (the Hägg or η carbide). 相似文献
6.
7.
Simulation of forging of Nb-stabilised Cr-Ni steel using a hot deformation simulator. Modelling of various courses of temperature in between and after deformation steps. Assessment of the effects of various soaking conditions on grain growth. Evaluation of recrystallisation and grain growth characteristics by quantitative metallography. 相似文献
8.
日益增长的工业需求推动着超级奥氏体不锈钢的研发,以研发时间为序阐述超级奥氏体不锈钢3个发展阶段。第1个阶段主要是为解决硫酸介质环境的耐腐蚀性而开发的不锈钢;第2个阶段是在第1阶段研发钢的基础上添加质量分数约为0.2%的N元素、并将Mo元素质量分数增加到约6%而研发的几种耐腐蚀性能良好的超级奥氏体不锈钢;第3个阶段是在6%Mo钢的基础上将Cr、Mo、N含量都进行较大幅度的提高,其中Mo元素质量分数增加到约7%,N元素质量分数控制在0.5%左右,并加入适量Mn元素而研发出耐腐蚀性优异的超级奥氏体不锈钢。阐述了超级奥氏体不锈钢研发过程中的2个重要技术,即炉外精炼与氮合金化技术,并展望了超级奥氏体不锈钢的未来发展及推广应用。 相似文献
9.
10.
The nonmetallic phase in 08X18H10T and 03X18H10 vacuum-treated austenitic stainless steel is investigated by means of a scanning electron microscope. The composition of the nonmetallic inclusions in cast samples of metal from the casting ladle, the vacuum unit, and the continuous-casting machine and samples of cold-rolled sheet (thickness 1.2 mm) is studied. In 08X18H10T steel samples from the tundish of the continuous-casting machine, the nonmetallic phase consists mainly of titanium-nitride aggregations, the crystals of which contain oxides of aluminum and titanium; a few of the nonmetallic inclusions are small globules with a titanium-oxide shell. In cold-rolled sheet, the nonmetallic inclusions are distributed over the whole cross section and consist of small (5–6 μm) crystals of titanium nitrides. Cast samples of 03X18H10 austenitic titanium-free steel are relatively free of nonmetallic inclusions. The nonmetallic phase consists mainly of small inclusions of alumocalcium silicate. In cold-rolled sheet (thickness 1.2 mm), the nonmetallic phase consists of a few very small globules (2–3 μm). The results are compared with the composition of the nonmetallic phase in analogous steel with no vacuum treatment. 相似文献
11.
Hydrogen attack in an austenitic stainless steel 总被引:1,自引:0,他引:1
M. J. Yacamán T. A. Parthasarathy J. P. Hirth 《Metallurgical and Materials Transactions A》1984,15(7):1485-1490
A titanium stabilized 321 grade austenitic stainless steel was exposed to hydrogen at 14 MPa pressure and at 873 K. Hydrogen
attack occurred in the form of small bubbles at alloy-carbide-matrix interfaces. The damaged regions were studied by transmission
electron microscopy, and the gas composition in the bubbles was analyzed. The results are discussed in terms of a thermodynamic
analysis of possible hydrogen attack reactions. 相似文献
12.
Cecil G. Rhodes Anthony W. Thompson 《Metallurgical and Materials Transactions A》1977,8(12):1901-1906
The stacking fault energy (SFE) of AISI 310 stainless steel was measured using the weak-beam, dark field technique on extended
nodes. The SFE was found to be 40 ± 5 mJ/m2, well below the 104 mJ/m2 predicted for this composition in earlier work by Schramm and Read. Difficulties with the Schramm and Read linear composition
approach to SFE were identified, and a representation of SFE using the Fe-Cr-Ni ternary diagram was suggested to provide a
more realistic, flexible and accurate picture of the composition dependence.
formerly with the Science Center, Rockwell International 相似文献
13.
对奥氏体不锈钢不同标距间伸长率的换算公式进行研究,结果表明:试验所得n值约为0.199,与标准中Olive公式的规定值存在一定的差异。 相似文献
14.
15.
16.
17.
The micro- and macrostructures of about 50 different stainless welds of the AISI/AWS 300 series are analyzed. The results
indicate that in welding condition corresponding to a typical SMA welding those and only those welds in which the ratio Creq/Nieq≲1.48, where Nieq and Creq are the nickel and chromium equivalents on the Schaeffler diagram, solidify with the austenite as the primary or leading
phase and the delta ferrite, if any, formed from the rest melt between growing cells or cellular dendrites of the austenite.
At room temperature these welds are characterized by a regular general microstructure, soft forms of the ferrite and relatively
large compositional differences mainly caused by solidification.
T. TAKALO, formerly Research Staff Member, University of Oulu 相似文献
18.
The macro-and microstructures of about fifty different stainless welds of the AISI/ AWS 300 series are analyzed. The results
indicate that under conditions corresponding to a typical shielded metal arc (SMA) welding the welds with a ratio in the range
1.48≾Cr
eq
/Ni
eq
≾1.95, where Ni
eq
and Cr
eq
are the nickel and chromium equivalents on the Schaeffler diagram, solidify in accordance with a duplex mode with the delta
ferrite as the primary (leading) phase. The austenite forms between ferrite dendrites through a three-phase reaction between
liquid, ferrite and austenite, and subsequently grows into the ferrite by either an equiaxial or an acicular mechanism, resulting
in a drastic decrease in the volume fraction of the delta ferrite. The micro-structure at room temperature is characterized
by a general irregularity and the varied morphology of the ferrite. The compositional differences observed at room temperature
are a consequence both of the solidification and the solid state transformation.
Formerly Research Staff Member, Laboratory of Physical Metallurgy, University of Oulu. 相似文献
19.
In situ measurements are reported of electrical resistance changes in 316 austenitic stainless steel after abruptly raising or lowering
temperature in the range from 440 °C to 550 °C subsequent to equilibration. These changes are found to be reproducible and
have a magnitude roughly proportional to the temperature change. They are believed to be manifestations of approach toward
a new state of shortrange order at the new temperature. Analysis of the kinetics indicates that very nearly a simple first-order
reaction is involved. The rate constants were found to have an activation energy of 3.18 ± 0.40 eV. By analogy with the Zener
relaxation, the temperature-change-induced short-range order which we observe is also believed to result from local atomic
rearrangements in which an average atom makes a relatively small (<10) number of jumps. Good agreement between our measured
relaxation rates and those calculated from extrapolated diffusion studies for iron, chromium, and nickel in comparable alloys
tends to substantiate the hypothesis that average atomic jump rates are being measured. 相似文献
20.
J. T. Al-Haidary A. A. Wahab E. H. Abdul Salam 《Metallurgical and Materials Transactions A》2006,37(11):3205-3214
The fatigue crack propagation rate (FCPR) in 316L austenitic stainless steel (ASS) and its weldments was investigated, at
two loading amplitudes, 7 and 8.5 kN, under tension-tension mode. Two welding techniques, submerged arc welding (SAW) and
manual arc welding (MAW), have been used. Magnetic δ-ferrite, depending upon Ni and Cr content in the metal, in the weld zone
upon solidification was considered. The ferrite number (FN) of δ-ferrite formed in the SAW zone was much higher (maximum 9.6)
compared to the corresponding value (maximum 0.75) in the MAW zone. A fatigue starter notch was positioned at different positions
and directions with respect to the weld zone, in addition to the heat-affected zone (HAZ). Regions of high and low FCPRs as
the fatigue crack propagated through and across the weld zone have been noticed. This is related to the direction of the tensile
residual stresses present in weld zone, resulting from solidification of the weld metal. The FCPR was higher along through
the HAZ and weld zone because of the microstructural change and direction and distribution of tensile residual stresses. The
FCPR was much lower when crack propagated perpendicular to the weld zone, particularly in the case of SAW in which higher
δ-ferrite volume fraction was noticed. A lower FCPR found across the weld zone, in both SAW and MAW, was accompanied by rubbed
areas in their fractures. 相似文献