Eutectoid Decomposition of δ-Ferrite in Ferritic-Austenitic Duplex Cast Steel - Structural and Morphological Study

2012 ◽  
Vol 706-709 ◽  
pp. 2314-2319 ◽  
Author(s):  
D. Dyja ◽  
Z. Stradomski ◽  
Cezary Kolan ◽  
Grzegorz Stradomski
Keyword(s):  
Annealing Temperature ◽  
Volume Fraction ◽  
Cast Steel ◽  
Optical Microscope ◽  
Rapid Progress ◽  
Phase Precipitation ◽  
X Ray ◽  
Σ Phase ◽  
Δ Ferrite ◽  
Surface Development

The influence of time and temperature of ageing on the σ-phase morphology in ferritic-austenitic cast steel have been investigated in this study. The morphology and quantity of the σ-phase were analyzed by using optical microscope, X-ray diffractometry, scanning electron microscope and image analysis, respectively. The annealing temperature has a significant influence on the morphology, volume fraction and the dynamics of σ-phase precipitation. Surface development of the σ-phase decreases from R=4.3, for the cast steel annealed at 700°C to R=2.4 for the cast steel annealed at 900°C, and the volume fraction Vvσ from 50.8% to 26.5%, respectively. The most rapid progress of δ → σ + γ’ transformation was observed at 800°C.

Microstructure Evolution in Isothermal Heat Treatment of 0Cr32Ni7Mo4NDuplex Stainless Steel

2014 ◽  
Vol 789 ◽  
pp. 314-319
Author(s):  
Yu Lai Chen ◽  
Hong He ◽  
Fei Fang
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Decomposition Reaction ◽  
Optical Microscope ◽  
Isothermal Heat Treatment ◽  
Σ Phase ◽  
Temperature Range ◽  
Δ Phase

The microstructure evolution of as-cast 0Cr32Ni7Mo4N hyper duplex stainless steel during the isothermal heat treatment in the temperature range of 800°C-1300°Cwas studied in the present investigation. The morphologies and precipitates were observed and determined by using optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). The results show that eutectoid decomposition reaction (δ→σ+γ2) take place in ferrite (δ) phase during isothermal heat treatment in the temperature range of 800°C-1000°C. Sigma (σ) phase and secondary austenite (γ2) phase coexist as cellular structure. Lamellar Cr2N precipitates in δ phase mostly when isothermal heat treatment at 800°Cand 850°C, while it only appears in γ phase between 900°C and 1050°C. As the annealing temperature rising, the quantity of σ phase, Cr2N and γ2 phase decreases. The volume fraction ratio of ferrite and austenite is stable between 1100°C and 1300°C, and γ → δ transformation is hard to occur.

The Study on the Precipitation and Mechanical Properties of Steel with Copper

2010 ◽  
Vol 654-656 ◽  
pp. 66-69 ◽  
Author(s):  
Chuang Li ◽  
Xue Min Wang ◽  
Xin Lai He ◽  
Cheng Jia Shang ◽  
Yu He
Keyword(s):  
Mechanical Properties ◽  
Electron Microscope ◽  
Volume Fraction ◽  
Optical Microscope ◽  
Second Phase ◽  
Phase Precipitation ◽  
Precipitation Behavior ◽  
Quenching Temperature ◽  
Bearing Steels ◽  
Transition Electron

The properties and precipitation behavior of Cu-bearing steels have been investigated. The optical microscope and transition electron microscope were employed to study the influence of interrupted cooling and quenching temperature on the precipitation behavior. Also, the properties of samples with different quench processes were tested. The results show that when the steel is interruptedly cooled and quenched from 650-700°C, with the quenching temperature increasing the volume fraction of martensite becomes larger and the hardness becomes higher. When the microstructure is ferrite the second-phase precipitates occurs and they are proved copper-rich particles. However there are no obvious precipitates in martensite. The copper-rich second phase forms by the way of inter-phase precipitation.

Effect of Homogenization on Recrystallization of Twin Roll Cast AA3003 Alloy

2013 ◽  
Vol 404 ◽  
pp. 122-126
Author(s):  
Yi You Tu ◽  
De Zhong Zhang
Keyword(s):  
Annealing Temperature ◽  
Volume Fraction ◽  
Resistivity Measurement ◽  
Optical Microscope ◽  
Intermetallic Particles ◽  
Temperature Homogenization ◽  
Homogenization Temperatures ◽  
Twin Roll Cast ◽  
Twin Roll ◽  
Electric Resistivity Measurement

The effect of homogenizations on the recrystallization microstructure of as-rolled twin roll cast AA3003 alloy were investigated using optical microscope, scanning electron microscopy and electric resistivity measurement. The results indicate that high temperature homogenization significantly decrease the supersaturation of Mn in the alloy, and both the volume fraction and the diameter of intermetallic particles increase as the homogenization temperatures. The shape of the recrystallized grains changes from pancake-like to equiaxed, as the annealing temperature increases above 520°C.

Phases in Austenitic Cast Steel

2012 ◽  
Vol 326-328 ◽  
pp. 215-220 ◽  
Author(s):  
Małgorzata Garbiak ◽  
Bogdan Piekarski
Keyword(s):  
Annealing Temperature ◽  
Cast Steel ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Cast State ◽  
Electrolytic Extraction ◽  
X Ray ◽  
Titanium Carbonitrides ◽  
C 30 ◽  
Double Carbides

The paper presents the characteristics of intermetallic phases occurring in heat-resistant cast austenitic 0.3% C-30% Ni-18% Cr steel with additions of niobium and titanium. Five alloys were examined, in which the content of the examined elements was (wt.%) Nb 0.03, 0.55, 1.57 and 1.92, and Ti 0.03, 0.05, 0.30, 0.83 and 1.00. The phase composition of alloys in as-cast state and after annealing (temperature of 800°C and 900°C, time of up to 300 hrs) was examined by X-ray diffraction technique. Depending on the chemical composition of cast steel, carbides of MC type (NbC, TiC, (Nb,Ti)C), M23C6, titanium carbonitrides TiCN and G phase were identified in its microstructure. The phase morphology was examined on the polished sections and surfaces of metallographic specimens after deep etching by electrolytic extraction method. It was found that M23C6carbides assume the shape of rods, NbC carbides crystallise in the form of lamellae, and titanium carbonitrides TiCN in the form of cubes. An addition of both the stabilising elements favours the formation of double carbides (Nb,Ti)C of octahedral habit.

Effects of Annealing Treatment on the Microstructure and Mechanical Properties of Magnesium Alloy Sheets

2013 ◽  
Vol 303-306 ◽  
pp. 2524-2527 ◽  
Author(s):  
Lei Wang ◽  
Guang Hui Min ◽  
Pan Pan Gao ◽  
Xin Ying Wang ◽  
Hua Shun Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Annealing Temperature ◽  
Annealing Treatment ◽  
Optical Microscope ◽  
Icosahedral Phase ◽  
Alloy Sheet ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray

The microstructure of magnesium alloy sheets (nominal composition Mg–6Zn–Y in at. %) was investigated with the Optical Microscope (OM), Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) technique after the annealing treatment. Tensile test at room temperature was performed to show the influence of annealing treatment on mechanical properties. Experimental results indicate that there are a large number of twin crystals appearing in microstructure of the extruded Mg-Zn-Y alloy sheet at 350 °C. The distinct icosahedral phase appears on the α-Mg matrix in granular form and the strength gets largely improved to the maximum. The uniform distribution of isometric crystal contributes to the best elongation at the annealing temperature of 400 °C.

Sol-gel derived Ba(Mg1/3Ta2/3)O3 thin films: Preparation and structure

1997 ◽  
Vol 12 (3) ◽  
pp. 596-599 ◽  
Author(s):  
Ji Zhou ◽  
Qing-Xin Su ◽  
K. M. Moulding ◽  
D. J. Barber
Keyword(s):  
Thin Films ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Small Grains

Ba(Mg1/3Ta2/3)O3 thin films were prepared by a sol-gel process involving the reaction of barium isopropoxide, tantalum ethoxide, and magnesium acetate in 2-methoxyethanol and subsequently hydrolysis, spin-coating, and heat treatment. Transmission electron microscopy, x-ray diffraction, and Raman spectroscopy were used for the characterization of the thin films. It was shown that the thin films tend to crystallize with small grains sized below 100 nm. Crystalline phase with cubic (disordered) perovskite structure was formed in the samples annealed at a very low temperature (below 500 °C), and well-crystallized thin films were obtained at 700 °C. Although disordered perovskite is dominant in the thin films annealed below 1000 °C, a low volume fraction of 1 : 2 ordering domains was found in the samples and grows with an increase of annealing temperature.

scholarly journals Kinetics of the σ Phase Precipitation in Respect of Erosion-corrosion Wear of Duplex Cast Steel

2014 ◽  
Vol 14 (1) ◽  
pp. 17-20 ◽  
Author(s):  
A. Brodziak-Hyska ◽  
Z. Stradomski ◽  
C. Kolan
Keyword(s):  
Flue Gas ◽  
Cast Steel ◽  
Strengthening Mechanism ◽  
Operating Conditions ◽  
Solid Particles ◽  
Corrosion Wear ◽  
Phase Precipitation ◽  
Σ Phase ◽  
Erosion Corrosion ◽  
Kinetics Of

Abstract The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3- 3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated up to 70°C and containing Cl' and SO4 ions and solid particles produce high erosive and corrosive wear.The work proposes an application of the σ phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material. The paper presents the results of examination of the kinetics of σ phase precipitation at a temperature of 800°C and at times ranging from 30 to 180 minutes. Changes in the morphology of precipitates of the σ phase were determined using the value of shape factor R. Resistance to erosion-corrosion wear of duplex cast steel was correlated with the kinetics of sigma phase precipitating.

scholarly journals The The effect of iron on precipitation hardening in the Cu-Ni-Mn alloys

2021 ◽  
Vol 22 (3) ◽  
pp. 487-493
Author(s):  
O.V. Sukhova
Keyword(s):  
Precipitation Hardening ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Iron Oxidation ◽  
Quantitative Metallography ◽  
Structure And Properties ◽  
X Ray ◽  
Temperature Ranges ◽  
Fe Alloys ◽  
Scanning Electron

The peculiarities in the structure and properties formation of precipitation-hardened Сu–Ni–Mn–Fe alloys within the concentration range of Ni (19.3–21.0 %), Mn (19.5–20.5 %), Fe (0.6–2.7 %), Cu – balance (in wt. %) were investigated in this work. The methods of quantitative metallography, X-ray analysis, scanning electron microscopy, energy-dispersive spectroscopy and differential thermal analysis were applied. Two solid solutions based on a-Cu differing in composition and hardness were found in the structure of the cast Сu–Ni–Mn–Fe alloys. The temperature ranges of solutions’ formation were determined as (1010±10) °С and (890±10) °С, correspondingly. NiMn phase was also formed at (405±15) °С due to precipitation hardening. In the Сu–Ni–Mn–Fe alloys annealed at 500 and 900 °С for 60–750 hours, the volume fraction and size of NiMn precipitates increased with prolonging annealing time and lowering annealing temperature. As iron content was raised up to 2.7 wt. %, the density of NiMn precipitates increased, especially during first 60 hours of annealing at 900 °С. By adding iron, oxidation resistance was improved, but melting temperature and fluidity did not yield any significant change. Hardness of the Сu–Ni–Mn–Fe alloys with higher iron contents increased by 10 НRB on average. However, when test temperature was raised up to 400 °С, tensile strength decreased (by ~1.3 times) and elongation dropped markedly (by ~10 times).

Microstructure Characterization of Duplex Stainless Steel Welding Joint with Different Solution and Aging Treatment

2010 ◽  
Vol 658 ◽  
pp. 376-379
Author(s):  
Jun Yang ◽  
Tuo Yan Zhang ◽  
Jun Hui Yu ◽  
Wei Zhang ◽  
Jiao Li
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Volume Fraction ◽  
Optical Microscope ◽  
Austenite Phase ◽  
Ferrite Phase ◽  
Solution Temperature ◽  
Eutectoid Reaction ◽  
Σ Phase ◽  
Stainless Steel Welding

The microstructural evolutions of 2205 duplex stainless steel welding joints were investigated in this paper. The specimens were solution treated at 1100°C and 1200°C for 1 h, water quenched and then isothermal aged for various durations at 850°C, followed by water cooling. The volume fraction of ferrite phase in HAZ, weld and base metal of the steel were measured by the ferrite scope detector. The changes of microstructure in sigma (σ) phase, ferrite and austenite phase were analyzed by optical microscope and energy dispersive spectrum. The results show that the volume fraction of ferrite phase increases and the ferrite grain becomes coarse when solution temperature enhances from 1100°C to 1200°C. During the aging, σ phase precipitates at γ/δ phase boundary and grows into the ferrite phase, and a eutectoid reaction of δ→σ+γ2 occurs. With extending of the aging time, the amount of ferrite phase decreases, σ phase increases and thin needle secondary austenite phase distributes across ferrite grains. In addition, high solution temperatures can delay the procedure of σ phase precipitation.

Effect of Annealing Temperature on Austenite Stability of a δ-TRIP Steel

2019 ◽  
Vol 818 ◽  
pp. 82-86
Author(s):  
Xin Xu ◽  
Ren Dong Liu ◽  
Bao Yu Xu ◽  
Hong Liang Yi ◽  
Guo Dong Wang
Keyword(s):  
Mechanical Properties ◽  
Trip Steel ◽  
Retained Austenite ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Austenite Stability ◽  
Poor Stability ◽  
Better Than

In this work, a novel type of δ-TRIP steel was designed, and the content and stability of retained austenite in δ-TRIP specimens under different annealing processes were detected and studied, respectively. The volume fraction of austenite was determined by X-ray diffraction (XRD). The microstructure and mechanical properties were analyzed systematically. The results show that a complex microstructure composed of three phases (ferrite, bainite and retained austenite) was obtained in the δ-TRIP steel. With the increasing of annealing temperature, both retained austenite and bainite content in the specimen increased, while the carbon content in retained austenite decreased, leading to a poor stability for retained austenite. Both tensile and yield strength improved with the increasing of annealing temperature, while the elongation reduced. The feature of retained austenite led to an excellent combination of ductility and strength, which was better than traditional TRIP steel.

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