Effect of Cooling Rate on the Microstructure and Precipitates of Directional Solidified 50W600 Non-oriented Silicon Steel

2013 ◽  
Vol 32 (6) ◽  
pp. 597-603
Author(s):  
Yong Wan ◽  
Wei-qing Chen ◽  
Shao-jie Wu
Keyword(s):  
Grain Size ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Silicon Steel ◽  
Growth Region ◽  
State Growth ◽  
Average Size ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
The Relationship

AbstractThe microstructure, morphologies of precipitates in directional solidified 50W600 non-oriented silicon steel with three cooling rates (0.095, 0.33 and 4.28 °C/s) were investigated. The results showed that the morphology of solid-liquid interface evolved from cellular to cellular dendritic, and then to dendritic with an increase of cooling rate. The grain size of specimen in the steady-state growth region decreased with increasing cooling rate. The precipitates in the steel were mainly four types as follows: AlN, MnS, AlN-MnS and Fe3C. The amount and volume fraction of precipitates firstly increased and then decreased with increasing cooling rate, and reached maximum values in the specimen with a cooling rate of 0.76 °C/s. The average size of precipitates decreased gradually with increasing cooling rate. The relationship between the average size of precipitates and cooling rate was D = 75.762·R−0.190.

Numerical Analysis of Aerospace Nickel-Based Single-Crystal Superalloy Weldability Part I: Crystallography-Dependent Dendrite Growth

2021 ◽  
Vol 1018 ◽  
pp. 3-12
Author(s):  
Zhi Guo Gao
Keyword(s):  
Single Crystal ◽  
Weld Pool ◽  
Dendrite Growth ◽  
Liquid Interface ◽  
Solidification Cracking ◽  
Microstructure Development ◽  
Growth Region ◽  
The Right ◽  
Solid Liquid Interface ◽  
Solid Liquid

The thermal-metallurgical modeling of microstructure development was further advanced during single-crystal superalloy weld pool solidification by coupling of heat transfer model, columnar/equiaxed transition (CET) model and multicomponent dendrite growth model on the basis criteria of minimum dendrite velocity, constitutional undercooling and marginal stability of planar front. It is clearly indicated that heat input (laser power and welding speed) and welding configuration simultaneously influence the stray grain formation, columnar/equiaxed transition and dendrite growth. For beneficial (001) and [100] welding configuration, the microstructure development along the solid/liquid interface is symmetrically distributed about the weld pool centerline throughout the weld pool. Finer columnar in [001] epitaxial dendrite growth region is kinetically favored at the bottom of the weld pool. For detrimental (001) and [110] welding configuration, the microstructure development along the solid/liquid interface is asymmetrically distributed. The dendrite trunk spacing along the solid/liquid interface from the beginning to end of solidification morphologically increases on the left side of the weld pool, while it spontaneously decreases on the right side. The vulnerable location of solidification cracking is confined in the [100] dendrite growth region on the right side of the weld pool because of increasing metallurgical contributing factors of severe stray grain formation, centerline grain boundary formation and coarse dendrite size. The mechanism of crystallography-dependent asymmetrical solidification cracking due to microstructure anomalies is proposed. It is crystallographically favorable for predominant morphology instability to deteriorate weldability. Active [100] dendrite growth region is diminished in the shallow elliptical weld pool by optimum low heat input (low laser power and high welding speed) with (001) and [100] welding configuration to essentially facilitate single-crystal solidification conditions and provide enough resistant to solidification cracking. Moreover, the theoretical predictions agree well with the experiment results. The reliable weldability maps are therefore established to determine the prerequisite for successful crack-free laser welding or cladding. The useful model is also applicable for other single-crystal superalloys with similar metallurgical properties.

scholarly journals Enhanced Mechanical Properties of Mg-6Sn-3Al-1Zn Alloy with Bimodal Grain Size Disturbed in the Microstructure Uniformly through Changing the Rolling Temperature

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Fuan Wei ◽  
Jinhui Wang ◽  
Ping Li ◽  
Bo Shi
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Strength ◽  
Volume Fraction ◽  
Rolling Temperature ◽  
Average Grain Size ◽  
Small Grains ◽  
Mg2sn Phase ◽  
Average Size ◽  
Bimodal Grain Size

The mechanical properties of Mg-6Sn-3Al-1Zn alloy were enhanced with bimodal grain size disturbed in the microstructure uniformly; the Mg-6Sn-3Al-1Zn alloys were rolled with 60% thickness reduction at different rolling temperatures. The results have shown that the Mg-6Sn-3Al-1Zn alloys are composed of Mg2Sn phase and α-Mg matrix phase. When the rolling temperature was less than or equal to 400°C, with the rolling temperature increasing, the average size and volume fraction of Mg2Sn phase and the average grain size of small grains remained unchanged, the average grain size of large grains decreased, the volume fraction of small grains increased, and the yield strength of the alloy increased. When the rolling temperature reached 450°C, the average size and volume fraction of Mg2Sn phase and the average grain size of large grains increased, and the volume fraction of small grains and the yield strength of the alloy decreased. The elongation increased with the rolling temperature increasing, but the change trend of hardness was just opposite. When the alloy was rolled at 400°C, the average sizes of small grains, large grains, and Mg2Sn phases were 3.66 μm, 9.24 μm, and 19.5 μm, respectively. The volume fractions of small grains, large grains, and Mg2Sn phases were 18.6%, 77.6%, and 3.8%, respectively. And the tensile properties reached the optimum; for example, the tensile strength, yield strength, elongation, and Vickers hardness were 361 MPa, 289.5 MPa, 20.5%, and 76.3 HV, respectively.

Effect of Heating Temperature on Microstructure of Directionally Solidified Ni-43Ti-7Al Alloy

2017 ◽  
Vol 898 ◽  
pp. 552-560 ◽  
Author(s):  
Lei Zhou ◽  
Li Jing Zheng ◽  
Hu Zhang
Keyword(s):  
Volume Fraction ◽  
Heating Temperature ◽  
Thermal Gradients ◽  
Directionally Solidified ◽  
Melt Structure ◽  
Cast Sample ◽  
The Stability ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Liquid Metal Cooling

By liquid metal cooling (LMC) process, the Ni-43Ti-7Al (at.%) alloy has been directionally solidified (DS) at different heating temperatures (1450°C, 1550°C, 1650°C) and a constant withdrawal rate of 100μm/s. The results showed that anomalous eutectic structures which consisted of Ti2Ni and TiNi phases were formed at the grain boundaries of as-cast sample and similar structures were also observed in the intercellular regions of DS samples. However, the microstructure changed from the equiaxial structure to the cellular structure due to the axial thermal gradients imposed. After DS, the NiTi and Ti2Ni phases preferentially grew along certain orientation, but the preferred crystallographic orientations of them changed as the heating temperature increased to 1650°C, which might be related to the change of melt structure. As expected, the volume fraction of Ti2Ni increased from 3.3% to 5.2% and the cellular spacing decreased from 47.8μm to 27.0μm as heating temperature increased. In addition, the stability of solid/liquid interface decreased, resulting from the coupling effects of G and ΔT- with the heating temperature increasing.

Crystal Growth Of A Decagonal AI-Co-Ni Quasicrystal

1998 ◽  
Vol 553 ◽  
Author(s):  
J.Q. Guo ◽  
T. J. Sato ◽  
T. Kimura ◽  
T. Hirano ◽  
A. P. Tsai
Keyword(s):  
Liquid Interface ◽  
Floating Zone ◽  
Solute Redistribution ◽  
Zone Method ◽  
Decagonal Quasicrystal ◽  
X Ray ◽  
State Growth ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Very High

AbstractWe have grown a decagonal single quasicrystal with a size of centimeter order in an A172Co16Ni12 alloy by floating zone method at a growth rate of 0.5 mm/h. The single decagonal quasicrystal has been inspected by Laue X-ray as well as neutron diffraction, revealing a very high quasicrystalline quality. By quenching the liquid during growth, a flat solid-liquid interface has been directly observed. There exists solute redistribution at the growing solid-liquid interface. At steady state growth Al is enriched and Co, Ni are depleted in front of solid-liquid interface. Solute partition ratios of Al, Co and Ni were determined to be about 0.91, 1.57 and 1.08, respectively.

scholarly journals The Effect of Cooling Rate on Mechanical Properties of Carbon Steel (St 35)

2014 ◽  
Vol 7 (1) ◽  
pp. 109-118
Author(s):  
Jenan Mohammed Nagie
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Carbon Steel ◽  
Cooling Rate ◽  
Experimental Results ◽  
Heat Treated ◽  
Before And After ◽  
Water Media ◽  
The Relationship

This paper is aimed to study the effect of cooling rate on mechanical properties of Steel 35. Specimens prepared to apply tensile, torsion, impact and hardness tests.Many prepared specimens heat treated at (850ºC) for one hour and subsequently were cooled by three different media [Water-Air-furnace] to show the effect of Medias cooling rate on mechanical properties. Microstructures of all specimens examined before and after heat treatment by an optical microscopy.To figure the phases obtained after heat treatment and its effect on the mechanical properties Experimental results have shown that the microstructure of steel can be changed and significantly improved by varying line cooling rate thus, improving one property will effect on the others because of the relationship between all properties.In water media tensile, torsion and hardness improved while impact results reduced. Air media contributed in improving most of the mechanical properties because of grain size homogeneity. At furnace media ductility and impact improved

Microstructure and texture evolution of medium temperature grain-oriented silicon steel produced by industrialization

2019 ◽  
Vol 116 (6) ◽  
pp. 604 ◽  
Author(s):  
Lifeng Fan ◽  
Liying Jia ◽  
Rong Zhu ◽  
Jianzhong He
Keyword(s):  
Grain Size ◽  
Texture Evolution ◽  
Silicon Steel ◽  
Rolled Strip ◽  
Medium Temperature ◽  
Goss Texture ◽  
Hot Rolled Strip ◽  
Average Grain Size ◽  
Average Size ◽  
Hot Rolled

The grain-oriented silicon steel was produced by medium temperature reheating and two-stage cold rolling process, and the microstructure and texture of all metallurgical processes were studied. The results shown that the microstructure of the hot rolled strip was inhomogeneous in thickness direction, the surface layer was the recrystallized microstructures with average grain size of 42.29 µm, the center layer was fiber structure, and the Goss texture appeared at surface. The primary recrystallized microstructure with average grain size of 16 µm was obtained after decarburization annealing, which characterized by a strong γ-fiber texture and a weak Goss texture. The average size of inhibitors in hot rolled strip and decarburization annealed sheet were 9.078 and 21.691 nm respectively, they were mainly compound of nitride and sulfide with spherical or lump shapes. The coarse Goss grains with average size 17.57 mm were got after secondary recrystallization, and the magnetic induction B8 and iron loss P1.7/50 were 1.885 T and 1.10 W/Kg, respectively.

scholarly journals Comparison of the Microstructure of M2 Steel Fabricated by Continuous Casting and with a Sand Mould

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 560
Author(s):  
Jinwen Zhang ◽  
Zhigang Zhao ◽  
Wenxian Wang ◽  
Yutian Wang
Keyword(s):  
Grain Size ◽  
Continuous Casting ◽  
Cooling Rate ◽  
Continuous Caster ◽  
Casting Process ◽  
Sand Mold ◽  
Average Grain Size ◽  
Kg Medium ◽  
The Relationship ◽  
Continuous Casting Billet

AISI M2 steel was smelted in a 150 kg medium-frequency induction furnace and cast to form round billets with a cross-section diameter of 100 mm via a vertical continuous caster and sand mold. The secondary dendrite arm spacing (λ2), cooling rates, permeability and size and distribution of grains and network carbides of the two billets were studied. The results show that the continuous casting process can effectively decrease the λ2 value, permeability and size of the grains and carbides and improve the distribution of the grains and carbides during solidification. The λ2 values of the billets cast with a sand mold and continuous caster are 37.34 μm and 21.14 μm, respectively, and the cooling rate is 3.6 K·s−1 and 12.0 K·s−1, respectively. The area fractions of carbides at the center of the billets cast with the sand mold and continuous caster are 0.24 and 0.16, respectively, and increase by 27.7% and 25.4%, respectively, compared with their average values. The average grain size of billets cast with the sand mold and continuous caster is 69.4 μm and 50.5 μm, respectively. Compared with the sand mold billet, the grain size at the center of the continuous casting billet is reduced by 25.5%. The relationship between the grain size and cooling rate is presented in this paper.

EFFECT OF THE SOLUTE REDISTRIBUTION ON THE GROWTH KINETICS IN SOLIDIFICATION

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3938-3943
Author(s):  
X. YAO
Keyword(s):  
Growth Rate ◽  
Solute Redistribution ◽  
Systematic Analysis ◽  
Constitutional Undercooling ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
The Relationship ◽  
Alloy Concentration ◽  
Interface Movement

Solute redistribution has been a long-term interest in solidification theoretical study, but its effect on growth rate during solidification is still not completely clear. Models that descript the relationship between growth rate and the alloy concentration remain controversial both qualitatively and quantitatively. This work theoretically analysed and investigated the solute redistribution and its effect on constitutional undercooling during solidification. Systematic analysis on the interaction behaviour between the solid/liquid interface movement and the solute distribution has been performed to clarify the effect of constitutional undercooling on growth rate of solid during solidification. It is demonstrated that the growth rate of crystals conversed to the alloy concentration and the relationship could be quantitatively calculated by the present model by introduction of the interface retardation.

Numerical Analysis of Solidification Behavior during Laser Welding Nickel-Based Single-Crystal Superalloy Part I: Crystallography-Dependent Solid Aluminum Distribution

2021 ◽  
Vol 1020 ◽  
pp. 13-22
Author(s):  
Zhi Guo Gao
Keyword(s):  
Single Crystal ◽  
Weld Pool ◽  
Heat Input ◽  
Dendrite Growth ◽  
Solidification Cracking ◽  
Aluminum Concentration ◽  
Growth Region ◽  
Solid Aluminum ◽  
Solid Liquid Interface ◽  
Solid Liquid

The thermal metallurgical modeling of alloying aluminum redistribution was further developed through couple of heat transfer model, dendrite selection model, multicomponent dendrtie grwoth model and nonequilibrium solidification model during three-dimensional nickel-based single-crystal superalloy weld pool solidification over a wide range of welding conditions (laser power, welding speed and welding configuration) to facilitate understanding of solidification cracking phenomena. It is indicated that the welding configuration plays more important role than heat input in aluminum redistribution. The bimodal distribution of solid aluminum concentration along the solid/liquid interface is crystallographically symmetrical about the weld pool centerline for (001) and [100] welding configuration, while the distribution of solid aluminum concentration along the solid/liquid interface is crystallographically asymmetrical throughout the weld pool for (001) and [110] welding configuration. The size of vulnerable [100] dendrite growth region is beneficially suppressed in favor of epitaxial [001] dendrite growth region through optimum low heat input (low laser power and high welding speed) to facilitate single-crystal dendrite growth for successful crack-free weld at the expense of shallow weld pool geometry. The overall aluminum concentration in (001) and [100] welding configuration is significantly smaller than that of (001) and [110] welding configuration regardless of heat input. Severe aluminum enrichment is confined to [100] dendrite growth region where is more susceptible to solidification cracking. Heat input and welding configuration are optimized in order to minimize the solidification cracking susceptibility and improve microstructure stability. The relationship between welding conditions and alloying aluminum redistribution are established for solidification cracking susceptibility evaluation. The higher heat input is used, the more aluminum enrichment is monotonically incurred by diffusion with considerable increase of metallurgical driving forces for morphology instability and microstructure anomalies to deteriorate weldability and vice versa. The mechanism of asymmetrical solidification cracking because of crystallography-dependent alloying redistribution is proposed. The theoretical predictions agree well with the experiment results. Moreover, the useful modeling is also applicable to other single-crystal superalloys with similar metallurgical properties during laser welding or laser cladding.

Sign in / Sign up

Export Citation Format

Share Document