scholarly journals Effect of Nb addition on the solidification structure of Fe–Mn–C–Al twin-induced plasticity steel

2020 ◽  
Vol 39 (1) ◽  
pp. 599-607
Author(s):  
Wen-Hui Du ◽  
Chang-Rong Li ◽  
Chang-Ling Zhuang
Keyword(s):  
Crystallization Rate ◽  
Solidification Process ◽  
Growth Direction ◽  
Solidification Structure ◽  
Second Phase ◽  
Second Phase Particles ◽  
Columnar Grains ◽  
Equiaxed Grains ◽  
Mn Steel

AbstractThe solidification microstructure of an Fe–Mn–C–Al high-Mn steel with added Nb was studied by optical microscopy and scanning electron microscopy. The results showed that the size of the columnar and equiaxed grains in the solidified structure of the high-Mn steel without added Nb was large. When Nb was added, the size of the equiaxed and columnar grains in the solidification structure of the high-Mn steel decreased. The twin-induced plasticity in the high-Mn steel with added Nb clearly refined the grain size of the solidified structure and simultaneously increased the equiaxed crystallization rate. The high-melting-point second-phase particles increased the heterogeneous nucleation rate, which was beneficial for grain refinement. A large amount of Nb precipitates from the solidification process increased the equiaxed crystallization rate of the solidified microstructure. The increased crystallization rate affected the growth direction of the columnar and equiaxed grains during solidification and indirectly decreased the probability of crack formation, which improved the quality of the twin-induced plastic steel.

Effect of Ca on Grain Size and Toughness in CGHAZ of C-Mn Steel

2011 ◽  
Vol 291-294 ◽  
pp. 886-889
Author(s):  
Kun Ning Jia
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Second Phase ◽  
Pinning Force ◽  
Second Phase Particles ◽  
Impact Experiment ◽  
Strong Pinning ◽  
Mn Steel

Through adding enough calcium to C-Mn steel, the second phase particles of CaO can be found in C-Mn steel. The microstructure, the grain size and the toughness of CGHAZ in micro-calcium steel and no micro-calcium steel were studied by TEM, SEM and series impact experiment. The research shows that: the second phase particles CaO in micro-calcium steel have strong pinning force to grain boundary of CGHAZ; the second phase particles can retard grain growth in the course of welding in micro-calcium steel, fining grain at CGHAZ and improving the toughness of CGHAZ in micro-calcium steel.

Investigation of Square Wave Pulsed Currents on Solidification Behavior of Al-Cu Alloys

2010 ◽  
Vol 160-162 ◽  
pp. 1767-1771
Author(s):  
Xiao Tian Yang ◽  
Xia Li ◽  
Wen Sheng Li
Keyword(s):  
Temperature Region ◽  
Solidification Process ◽  
Solidification Structure ◽  
Recording Instrument ◽  
Metal Solidification ◽  
Square Wave ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Temperature Recording ◽  
Equiaxed Grains

Al-(4-5)%Cu alloy was served as experiment material，the effect of pulsed currents on the solidification structure was investigated. During the solidification process of Al-Cu alloys, pulsed currents was added into the melted alloy in the crucible .The change of temperature curve and microstructure about the alloy was investigated in such conditions by temperature-recording instrument and optical microscope.The results showed that pulsed currents can shorten the temperature region of crystallization and refine the grains of the alloy,which crush the dendrite and make the solidification structure non-dendrite, presenting columnar and equiaxed grains which are distributed evenly and whose space between crystals are reduced. This investigation firstly started to study the relations between the temperature region of crystallization and organization structure of solidification. Finally, the mechanism of metal solidification affected by square wave pulsed currents was discussed.

Influence of Different Roll Casting Conditions on Casting Microstructure

2013 ◽  
Vol 652-654 ◽  
pp. 2432-2436
Author(s):  
Xiao Bo Liu ◽  
Wen Kang Yan
Keyword(s):  
Casting Speed ◽  
Casting Machine ◽  
Longitudinal Direction ◽  
Solidification Structure ◽  
Columnar Crystal ◽  
Aluminum Strip ◽  
Roll Casting ◽  
Columnar Grains ◽  
Columnar Grain ◽  
Equiaxed Grains

The changes of roll casting microstructure under different casting conditions on experimental casting machine was studied, which showed that solidification microstructure is different with different casting speed and thickness. When the casting speed is 1.3m/min,the thickness of strip is 6mm, coarse columnar grain dominates the solidification structure; when it continuously increases to 4m/min, the thickness of strip is 3mm, aluminum strip shows as hybrid organization with columnar grains in two sides and small equiaxed grains in the center; when the casting speed is over 12m/min,the thickness of strip is 1.75mm, columnar grains all convert into equiaxed grains in solidification structure. The deformation microstructures are different with the different casting speed and thickness of strip. When the casting speed is 0.9m/min, the thickness of strip is 6mm, typical processing flow lines come into being along longitudinal direction and transverse direction shows as squashed grains without re-crystallization. When the casting speed is 5.4m/min, the thickness of strip is 2.5mm, microstructure of aluminum strip becomes chevron organization from columnar crystal, there is a condensate in the center of aluminum strip, and the deformation of outer metal is more serious than inner, incomplete dynamic recrystallized grains come into being in the outer metal of the aluminum strip.

Structure Evolution of Fe-Mn Based Alloys under a Near-Rapid Solidification Process

2014 ◽  
Vol 1015 ◽  
pp. 3-9 ◽  
Author(s):  
Wei Lu ◽  
Zheng Yan Shen ◽  
Yang Yang ◽  
Yun Hu Zhang ◽  
Chang Jiang Song ◽  
...  
Keyword(s):  
Rapid Solidification ◽  
Manganese Content ◽  
Solidification Process ◽  
Martensite Phase ◽  
Structure Evolution ◽  
Austenitic Phase ◽  
Columnar Grains ◽  
Ε Martensite ◽  
Equiaxed Grains ◽  
Equiaxed Grain

A series of near-rapid solidification experiments were performed to investigate the structure evolution in Fe-(6, 11, 13, 17, 21) wt.% Mn and Fe-11wt.%Mn-(0.1, 0.5,1.4) wt.% C strips. The α’-martensite of body-centered cubic structures were observed in all Fe-Mn alloy strips. The ε-martensite phase appeared when the manganese content was up to 13wt.% and its amount gradually increased with the increasing of manganese content. The austenitic phase began to appear in Fe-21wt.%Mnstrip. As for the solidified structure analysis, the Fe-13wt.%Mn strip had a quite large equiaxed grain zone, while other Fe-Mn strips mainly consisted of columnar grains grew from the surfaces. The addition of 0.1wt.%C was helpful for the formation of ε-martensite in Fe-11wt.%Mn strip, but the addition of 0.5 and 1.4wt.%C promoted the transformation of ε-martensite to austenite phase. And addition of 0.5wt.% carbon could increase the area ratio of equiaxed grains formation.

Simulation of Solidification and Convection of NH4Cl-H2O Solution in a Water-Cooled Copper Mold

2014 ◽  
Vol 790-791 ◽  
pp. 247-252 ◽  
Author(s):  
Mahmoud Ahmadein ◽  
Meng Huai Wu ◽  
Mehaela Stefan Kharicha ◽  
Abdella Kharicha ◽  
Andreas Ludwig
Keyword(s):  
Solidification Structure ◽  
Copper Mold ◽  
Solidification Model ◽  
Piv Technique ◽  
Image Velocimetry ◽  
Columnar Grains ◽  
Subsequent Step ◽  
Simulation And Experiment ◽  
Equiaxed Grains ◽  
Zone Temperature

The convection pattern and the evolution of mushy zone, temperature and solidification structure are measured during solidification of NH4Cl-70%H2O solution in a water-cooled copper mold with transparent sidewalls. The natural convection and crystal sedimentation are measured via Particle Image Velocimetry (PIV) technique. This experiment is simulated using a 5-phase mixed columnar-equiaxed solidification model proposed by current authors [Comp. Mater. Sci. 50 (2010) 32-4]. The 5 phases comprise the extradendritic melt, the solid dendrite and interdendritic melt inside the equiaxed grains, the solid dendrite and interdendritic melt inside the columnar grains. Melt convection and crystal sedimentation are considered. It is demonstrated that the experimentally observed flow patterns and the solidification structure can be qualitatively reproduced. Reasons for the quantitative deviation between the simulation and experiment are discussed. Analysis of the modeling results in details and improvement of the calculation accuracy will be in a subsequent step.

The Superplastic Deformation and Microstructural Analysis of Fine-Grained 1420 Al-Li Alloy

2010 ◽  
Vol 148-149 ◽  
pp. 434-438
Author(s):  
Yan Ling Zhang ◽  
He Ping Guo ◽  
Zhi Qiang Li
Keyword(s):  
Strain Rate ◽  
Microstructural Analysis ◽  
Constant Strain Rate ◽  
Rolling Process ◽  
Second Phase ◽  
Fine Grained ◽  
Second Phase Particles ◽  
Before And After ◽  
Deformation Strain Rate ◽  
Equiaxed Grains

The superplasticity of fine-grained 1420 Al-Li alloy which was prepared by two-stage aging and turning rolling process was studied by constant-strain-rate tensile test. The results showed that: good superplasticity was attained at temperature range of 460°C~520°C and deformation strain rate 1×10-4s-1~5×10-3s-1. An elongation of 650% was obtained at the temperature of 650°C and strain rate of 1×10-4s-1. Furthermore, the microstructures of material before and after deformation were examined using OM and TEM. Equiaxed grains were still kept, and the second-phase particles and dislocations were observed in the deformed samples.

scholarly journals Automotive Steel with a High Product of Strength and Elongation Used for Cold and Hot Forming Simultaneously

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1121
Author(s):  
Fei Huang ◽  
Qiwei Chen ◽  
Hanlin Ding ◽  
Yongqiang Wang ◽  
Xiuting Mou ◽  
...  
Keyword(s):  
Low Cost ◽  
Residual Austenite ◽  
Hot Forming ◽  
Second Phase ◽  
Good Oxidation Resistance ◽  
Multiphase Microstructure ◽  
Medium Mn Steel ◽  
Second Phase Particles ◽  
Automotive Steel ◽  
Mn Steel

A low-cost and easy-to-produce C–Mn–Cr automotive steel for both cold and hot forming is presented in this paper. The alloying element Cr was used to replace Mn in medium-Mn steel and instead of B in hot-formed steel, in order to achieve microstructure control and hardenability improvement, replacing the residual austenite-enhanced plasticization with multidimensional enhanced plasticization through multiphase microstructure design, grain refinement, and dispersion enhancement of second-phase particles. The products of strength and elongation for the cold-formed and hot-formed steel were 20 GPa·% and 18 GPa·%, respectively, while the tensile strengths were more than 1000 MPa and 1500 MPa, respectively. This new automotive steel was also characterized by good oxidation resistance. The mechanisms of strength and plasticization of the experimental automotive steel were analyzed.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

Analytical Electron Microscopy Study of Second-Phase Particles in 7075 and 7475 Aluminum Alloys

1985 ◽  
Vol 43 ◽  
pp. 348-349
Author(s):  
M. Raghavan ◽  
J. Y. Koo ◽  
J. W. Steeds ◽  
B. K. Park
Keyword(s):  
Aluminum Alloys ◽  
Silicon Oxide ◽  
Analytical Electron Microscopy ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Partial Substitution ◽  
Second Phase ◽  
X Ray ◽  
Second Phase Particles ◽  
Almost All

X-ray microanalysis and Convergent Beam Electron Diffraction (CBD) studies were conducted to characterize the second phase particles in two commercial aluminum alloys -- 7075 and 7475. The second phase particles studied were large (approximately 2-5μm) constituent phases and relatively fine ( ∼ 0.05-1μn) dispersoid particles, Figures 1A and B. Based on the crystal structure and chemical composition analyses, the constituent phases found in these alloys were identified to be Al7Cu2Fe, (Al,Cu)6(Fe,Cu), α-Al12Fe3Si, Mg2Si, amorphous silicon oxide and the modified 6Fe compounds, in decreasing order of abundance. The results of quantitative X-ray microanalysis of all the constituent phases are listed in Table I. The data show that, in almost all the phases, partial substitution of alloying elements occurred resulting in small deviations from the published stoichiometric compositions of the binary and ternary compounds.

Reproduction of the Roman snail (Helix pomatia L.) from a local natural population in farm conditions and in a natural habitat

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Maciej Ligaszewski ◽  
Przemysław Pol
Keyword(s):  
Natural Population ◽  
Natural Habitat ◽  
Local Population ◽  
Helix Pomatia ◽  
Second Phase ◽  
Animal Reproduction ◽  
Snail Helix Pomatia ◽  
June July ◽  
A Site

AbstractThe aim of this study was to compare the quality of clutches and reproduction results of two groups of Roman snails (Helix pomatia) from the same local population, laying eggs simultaneously in semi-natural farm conditions and in a natural habitat. The study material were Roman snails aged 2 or more years which had entered the third phenological season of their life and thus the first season of sexual maturity. Observations were conducted at an earthen enclosure in a greenhouse belonging to the experimental farm for edible snails at the National Research Institute of Animal Reproduction in Balice near Kraków (Poland) as well as at a site where a local population naturally occurs in the uncultivated park surrounding the Radziwiłł Palace. In the June-July season, differences among such parameters as weight of clutch, number of eggs in clutch, mean egg weight, and hatchling percentage when compared to the total number of eggs in the clutch were compared. It was determined that clutches of eggs from the natural population laid in the greenhouse were of lesser weight (P<0.01), contained fewer eggs (P<0.05), and the mean weight of individual eggs was less (P<0.05) than in clutches laid simultaneously in a natural habitat. Both in the greenhouse and the natural habitat, in the first phase of laying eggs (June) the weight of the clutch and number of eggs its contained were greater than in the second phase (July). However, only for snails laying eggs in the greenhouse were these differences statistically significant (P<0.05) and highly significant (P<0.01), respectively. Statistically significant differences were not observed in hatchling percentage between eggs laid in the greenhouse and the natural habitat. The lower number of eggs laid in the farmed conditions of the greenhouse was successfully compensated for by the absence of mass destruction by rodents which occurred in the natural habitat.

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