scholarly journals Evolution and Evaluation of Duplex Grain of As-cast 30Cr2Ni4MoV Steel during Heat Treatment

2020 ◽  
Vol 26 (3) ◽  
pp. 281-286
Author(s):  
Xiuzhi ZHANG ◽  
Zhilong LIU ◽  
Jiansheng LIU ◽  
Shue DANG
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Isothermal Holding ◽  
Optical Microscope ◽  
Treatment Temperature ◽  
Heating Process ◽  
Isothermal Heat Treatment ◽  
Austenite Grains ◽  
Different Grain Size ◽  
Heat Preservation

As the main microstructure flaw of heavy forging, duplex grain (the grain size is non-uniform) may result in producing a reject. In this paper, the influences of heat treatment temperature and isothermal holding time on the duplex grains evolutions of as-cast 30Cr2Ni4MoV steel were studied using optical microscope and scanning electron microscope aided with XRD and EDS. It is shown that the globular austenite grains appear at 750 °C and the austenite grains in the regions rich in C, Cr, Ni, and Mo are smaller than that in other regions. Duplex grains appear in the heating process. Moreover, in the isothermal heat treatment process, grains with different grain size number also developed at all of the temperatures performed in the study. But the distribution of the grains with different sizes cannot be evaluated precisely using proper method commonly used now. On the basis of analysis of the sizes of the duplex grains, a new approach for evaluating the level of the mixture of different size grains was proposed, the result obtained are consistent with the experimental results. The microstructure of 30Cr2Ni4MoV could be more uniform by increasing the temperature and extending the heat-preservation time.

Modeling of Dual-Phase Grain Structure in Ti-6Al-4V during Isothermal and Non-Isothermal Heat Treatment by Using Cellular Automata

2013 ◽  
Vol 753 ◽  
pp. 353-356
Author(s):  
Alfred Krumphals ◽  
Cecilia Poletti ◽  
Fernando Warchomicka ◽  
Martin Stockinger ◽  
Christof Sommitsch
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Cellular Automata ◽  
Isothermal Holding ◽  
Equilibrium Phase ◽  
Beta Phase ◽  
Grain Structure ◽  
Isothermal Heat Treatment ◽  
Dual Phase ◽  
Two Phase

In the titanium alloy Ti-6Al-4V the dual-phase grain structure, which forms during thermo-mechanical processing, is of high importance due to its effect on the mechanical properties. In general the most significant microstructural parameters are the amount of alpha and beta phase as well as their grain size. For this reason a new cellular automata method (CA) was developed to predict the evolving grain structure during isothermal and non-isothermal heat treatment. The probabilistic CA model is based on the diffusion controlled movement of grain and phase boundaries. During temperature changes an algorithm is adjusting alpha and beta phase fraction to maintain equilibrium phase values. Hence, the CA is capable to calculate grain coarsening as well as grain growth and shrinking in the two-phase area while heating and isothermal holding at forging temperature. The initial microstructure can be imported form virtual created microstructures, real micrographs and EBSD-images. The results are mean grain diameters, grain size distributions and virtually simulated microstructures which can be easily compared with real micrographs. The predicted microstructures are showing a good correlation to data in literature and experimental results.

Isothermal Oxidation Behavior of Fe-33Ni-18Cr Alloy in Different Heat Treatment Temperature

2020 ◽  
Vol 1010 ◽  
pp. 46-51
Author(s):  
Zahraa Zulnuraini ◽  
Noraziana Parimin
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Heat Treatment Temperature ◽  
Minimum Weight ◽  
Isothermal Oxidation ◽  
Optical Microscope ◽  
Treatment Temperature ◽  
Grain Structure ◽  
X Ray ◽  
Average Grain Size

This research study describes the influence of different heat treatment temperature on isothermal oxidation of Fe-33Ni-18Cr alloy. The Fe-33Ni-18Cr alloy was undergone heat treatment at three different temperatures, namely 1000 °C, 1100 °C and 1200 °C for 3h soaking time followed by water quench to vary the grain size of the alloy. This alloy was ground by using several grit of silicon carbide papers as well as weighed by using analytical balance and measured by using Vernier caliper before oxidation test. The heat-treated Fe-33Ni-18Cr alloy was isothermally oxidized at 800 °C for 150h. The characterization of oxidized samples was carried out using optical microscope, scanning electron microscope equipped with energy dispersive x-ray (SEM-EDX) and x-ray diffraction (XRD). The results showed that, increasing the heat treatment temperature was increased the average grain size. The kinetics of oxidation followed the parabolic rate law which represents diffusion-controlled oxide growth rate. Fine grain structure of 1000 °C sample shows minimum weight gain and lower oxidation rate compared to samples of 1100 °C and 1200 °C that indicated oxide spallation and porous structure. Besides, phase analysis showed that the oxidized sample formed several oxide phases.

MODIFICATION OF Mg2Si MORPHOLOGY IN A Mg-3Si-3Sn ALLOY DURING ISOTHERMAL HEAT TREATMENT

2009 ◽  
Vol 23 (06n07) ◽  
pp. 849-854
Author(s):  
LIU XIAO ◽  
XINLIN LI ◽  
XiANG WANG ◽  
GUO RUI MA ◽  
DAN FENG
Keyword(s):  
Heat Treatment ◽  
Heat Treatment Temperature ◽  
Isothermal Holding ◽  
Spherical Shape ◽  
Treatment Temperature ◽  
Chinese Script ◽  
Isothermal Heat Treatment

The effects of different isothermal holding temperatures and times on the morphology of Chinese script shaped or fibriform eutectic Mg 2 Si phases in a Mg -3 Si -3 Sn alloy were investigated during isothermal heat treatment. With increasing heat treatment temperature, the spheroidizing time for the coarse eutectic Mg 2 Si phases is reduced dramatically. After isothermal heat treatment of 2 h at 550°C, the morphology of the eutectic Mg 2 Si transforms completely from the coarse Chinese script type and fibriform shape into fine, spherical shape with the lowest interface energies. The spheroidizing mechanism of the Chinese script shaped or fibriform eutectic Mg 2 Si particles seems to be attributed to the 'Rayleigh shape instability'.

scholarly journals Significantly fast spinodal decomposition and inhomogeneous nanoscale martensitic transformation in Ti–Nb–O alloys

2020 ◽  
Vol 321 ◽  
pp. 11049
Author(s):  
Yuya ISHIGURO ◽  
Yuhki TSUKADA ◽  
Toshiyuki KOYAMA
Keyword(s):  
Heat Treatment ◽  
Martensitic Transformation ◽  
Spinodal Decomposition ◽  
Treatment Temperature ◽  
Phase Field Method ◽  
Isothermal Heat Treatment ◽  
Phase Decomposition ◽  
Rate Condition ◽  
Continuous Cooling ◽  
Β Phase

The β phase spinodal decomposition during continuous cooling in Ti‒Nb‒O alloys is investigated by the phase-field method. Addition of only a few at.%O to Ti‒23Nb (at.%) alloy remarkably increases the driving force of the β phase spinodal decomposition. During isothermal heat treatment at 1000 K and 1100 K in Ti‒23Nb‒3O (at.%) alloy, the β phase separates into β1 phase denoted as (Ti)1(O, Va)3 and β2 phase denoted as (Ti, Nb)1(Va)3, resulting in the formation of nanoscale concentration modulation. The phase decomposition progresses in 0.3‒20 ms. In Ti‒23Nb‒XO alloys (X = 1.0, 1.2, 2.0), the spinodal decomposition occurs during continuous cooling with the rate of 500 K s‒1, indicating that the spinodal decomposition occurs during water quenching in the alloys. It is assumed that there is a threshold value of oxygen composition for inducing the spinodal decomposition because it does not occur during continuous cooling in Ti‒23Nb‒0.6O (at.%) alloy. The concentration modulation introduced by the β phase decomposition has significant effect on the β→α” martensitic transformation. Hence, it seems that for controlling microstructure and mechanical properties of Ti‒Nb‒O alloys, careful control of heat treatment temperature and cooling rate condition is required.

High Indentation Resistance of Aluminum Borate Based Glass-Ceramics

2013 ◽  
Vol 545 ◽  
pp. 3-7
Author(s):  
Pat Sooksaen ◽  
Pisud Prasertcharoensuk ◽  
Jiraporn Damnernsawat ◽  
Nimit Pattamawitayanimit
Keyword(s):  
Heat Treatment ◽  
Glass Melting ◽  
Isothermal Holding ◽  
Surface Hardness ◽  
Glass Ceramics ◽  
Isothermal Heat Treatment ◽  
Aluminum Borate ◽  
Holding Period ◽  
Heating And Cooling ◽  
Heat Treated

This study investigated the bulk crystallization of 54B2O3-19SiO2-17Al2O3-5BaO-5MgO (mol%) glass. Melting was carried out at 1500°C for 1 h using a bottom-load electric furnace. The glass melt was cast into a block and annealed at 500°C for 2 h. Isothermal heat treatment was carried out at 1100°C for 2, 4, 8, 16, 32 h to form bulk crystallized glass-ceramics using a heating and cooling rate of 5°C/min. Phases present in the glass-ceramic samples were studied by x-ray diffraction. Crystalline Al4B2O9 and Al18B4O33 were the main phases and the phase stability depended on the isothermal time. Microstructures were observed by a scanning electron microscope. The size of aluminum borate whiskers/rods tend to increase with longer isothermal holding period. The whisker/ rod-like crystals uniformly oriented throughout the microstructure in all heat treated samples. This led to interlocking microstructure and hence an increase in hardness and fracture toughness. Glass-ceramics synthesized at longer heat treatment times resulted in an increase in the surface hardness and shorter path length at the corner of the diamond pyramid-shaped indenter. Glass-ceramics synthesized in this study can be applied as high temperature resistant machinable materials because their microstructures can resist micro-cracking upon indentation.

scholarly journals Effect of Heat-Treatment on the Thermal and Mechanical Stability of Ni/Al2O3 Nanocrystalline Coatings

2020 ◽  
Vol 4 (1) ◽  
pp. 17
Author(s):  
Kavian O. Cooke ◽  
Tahir I. Khan ◽  
Muhammad Ali Shar
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Mechanical Stability ◽  
Chemical Properties ◽  
Treatment Temperature ◽  
Al2o3 Coating ◽  
Operational Temperature ◽  
Average Grain Size ◽  
Properties Of Materials ◽  
Physical And Chemical

Heat-treatment is a frequently used technique for modifying the physical and chemical properties of materials. In this study, the effect of heat-treatment on the mechanical properties, thermal stability and surface morphology of two types of electrodeposited coatings (pure-Ni and Ni/Al2O3) were investigated. The XRD analyses showed that the crystal structure of the as-deposited coating changes from slightly amorphous to crystalline as the heat-treatment temperature increases. The heat-treatment of both the pure-Ni and the Ni/Al2O3 coating caused an increase of the grain size within the coatings. However, the unreinforced Ni coating experienced a faster growth rate than the Ni/Al2O3 coating, which resulted in a larger average grain size. The temperature-driven changes to the microstructure of the coatings caused a reduction in the hardness and wear resistance of the coatings. The presence of nanoparticles within the Ni/Al2O3 coating can successfully extend the operational temperature range of the coating to 473 K by pinning grain boundaries.

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 Effects of Hot Deformation Parameters on the Size of Dynamically Recrystallised Austenite Grains of HSLA Steel

2019 ◽  
Author(s):  
Sebastian Gnapowski ◽  
Elżbieta Kalinowska- Ozgowicz ◽  
Mariusz Sniadkowski ◽  
Aleksandra Pietraszek
Keyword(s):  
Grain Size ◽  
Hot Deformation ◽  
Hsla Steel ◽  
Optical Microscope ◽  
Austenite Grain Size ◽  
Deformation Parameters ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Ebsd Technique ◽  
Scanning Electron

This paper presents the results of investigations of the effects of hot deformation parameters in compression investigation on the austenite grain size in HSLA steel (0.16% C, 0.037% Nb, 0.004% Ti, 0.0098% N). The axisymmetric compression investigations were performed on cylindrical investigation specimens of d=1.2 using the Gleeble 3800 simulator. The strain rate=1s-1÷15.9s-1 and strain degree ε=1.2. Before deformation, the research specimens were austenitized at TA = 1100 ÷ 1250 °C. Metallographic observations of the primary austenite grains were conducted with an optical microscope, while the structure of dynamically recrystallized austenite, inherited by martensite, was examined by EBSD technique using a scanning electron microscope. Based on the analysis of investigation results, it was found that the size of dynamically recrystallized austenite grains in HSLA steel were clearly affected by hot compression parameters. In contrast, no significant impact of austenitising temperature on their size was found.

Effects of SiC Particle and Holding Time on Semi-Solid Microstructure of SiCP/AZ61 Composites

2010 ◽  
Vol 152-153 ◽  
pp. 628-633
Author(s):  
Fa Yun Zhang ◽  
Jian Xiong Ye ◽  
Hong Yan
Keyword(s):  
Heat Treatment ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Isothermal Holding ◽  
Holding Time ◽  
Isothermal Heat Treatment ◽  
Particle Volume ◽  
Semi Solid ◽  
Sic Particle

Effects of SiC particle and holding time on microstructure evolution of SiCP/AZ61 composites during semi-solid isothermal heat treatment method were studied, and evolution mechanism of semi-solid microstructure of composites was discussed. The results indicated that the process of microstructure evolution of SiCP/AZ61 composites by the isothermal holding at the temperatures of 595°C for different times (0min~90min) experienced in succession the rapid merging of the secondary dendritic arms →large massive structure→melting and separating of the local grain boundary →spheroidization of the gains →slowing growth of globular microstructure. Synthetically, after isothermal holding at 595°C for 30min to 60min the favorable semi-solid microstructure can be obtained; Compared with the monolithic AZ61alloy, microstructure of SiCP/AZ61 composites during semi-solid isothermal heat-treatment was finer as a result of entering of Sic particle, and with the increasing of SiC particle volume fraction, globular gain size was smaller.

Effect of Heat Treatment Temperature on the Spinning Structure and Properties of a Cu–Sn Alloy

2019 ◽  
Vol 26 (1) ◽  
pp. 29-35
Author(s):  
Jinli Liu ◽  
Wenyuan Zheng ◽  
Huiqin Yin
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Grain Boundary ◽  
Heat Treatment Temperature ◽  
Treatment Temperature ◽  
Recrystallization Temperature ◽  
Boundary Orientation ◽  
Different Temperatures ◽  
Alloy Microstructure ◽  
Electron Back Scattered Diffraction

AbstractA thin-walled copper (Cu)–tin (Sn) alloy cylinder was treated after spinning at 200–400°C for 0.5 h. The characteristics of the alloy microstructure under different temperatures were analyzed through electron back-scattered diffraction. The results were as follows. The grain size at 200–300°C decreases as the heat treatment temperature rises, but the grain size at 400°C increases. At 200–300°C, the microstructure primarily consists of deformed grains. It is found that the main reason for the formation of high-angle grain boundaries (HAGBs) is static recrystallization. For the grain boundary orientation differential, the low-angle sub-grain boundary gradually grows into the HAGB, and multiple annealing twin Σ9 boundaries appear. Grain orientation is generally random at any temperature range. The mechanical property test indicated that, at the upper critical recrystallization temperature of 300°C, the elongation of the Cu–Sn alloy gradually increases, and its yield strength and ultimate tensile strength rapidly decrease.

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