scholarly journals Thermodynamics Analysis of Multiple Microelements’ Coupling Behavior in High Fatigue Resistance 50CrVA Spring Steel with Nanoparticles

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2952
Author(s):  
Yanlin Wang ◽  
Lihua Fu ◽  
Meng Zhou ◽  
Zirong Zhou ◽  
Xiaolu Pang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Fatigue Life ◽  
Secondary Phase ◽  
Spring Steel ◽  
Secondary Phases ◽  
Constitutional Liquation ◽  
High Fatigue ◽  
Different Temperatures ◽  
Phase Size ◽  
Order Of Magnitude

Solid solution and coupling precipitation behavior of multiple microelements in 50CrVA spring steel under different temperatures were analyzed based on thermodynamics. Quantitative relationships between the multiple microelements’ contents and secondary phases, and their effects on fatigue life, were systematically studied in conjunction with the secondary phase microstructure characterization using scanning and transmission electron microscopy, etc. The solid solution contents of different microelements decreased as the temperature decreased, especially N and Ti, but the number of compounds gradually increased when the temperature decreased. Carbonitride constitutional liquation occurred in 50CrVA-S1# spring steel-containing microparticles, and without carbonitrides, constitutional liquation occurred in 50CrVA-S2# spring steel-containing nanoparticles. The experimental results indicate that the fatigue life reduces by about an order of magnitude when the secondary phase size changes from nanometers to microns, and the corresponding relationship among multiple microelements, microstructure of secondary phases, and fatigue life, was established in this spring steel.

The Effect of Heat-Treatment on the Phase Stability of Fe-28Al-15Si-2Mo Alloy

2020 ◽  
Vol 405 ◽  
pp. 80-85
Author(s):  
Věra Vodičková ◽  
Martin Švec ◽  
Pavel Hanus ◽  
Petra Pazourková Prokopčáková
Keyword(s):  
Solid Solution ◽  
Phase Stability ◽  
Secondary Phase ◽  
Hardness Measurement ◽  
Secondary Phases ◽  
Solid Solution Strengthening ◽  
High Temperature Mechanical Properties ◽  
Molybdenum Addition ◽  
Bulk Hardness ◽  
Solution Strengthening

The structures of Fe-28Al-15Si-2Mo iron aluminide in as cast state and in three states after heat-treatments were investigated for the verification of secondary phases stability. Short-term (at 1000 °C for 24 h and at 1200 °C for 2 h) as well as long-term (at 800 °C for 100 h) annealing were performed. Molybdenum addition enhances the high-temperature mechanical properties due to solid solution strengthening, however the mechanism of hardening could be modified (to solid solution strengthening + strengthening by incoherent precipitates) by another alloying element (f. e. Si or C). The phase compositions of alloys were described by means of scanning electron microscopy equipped with energy dispersive analysis. The complex Fe-Si-Mo carbides were found in the structure. The bulk hardness measurement and image analysis were performed for the verification of secondary phase stability. Particles became coarse with increasing temperature of annealing.

Effect of Sintering Conditions on the Phase Formation and Microstructure of Bi-2223/Ag/Ni Composite-Sheathed Tapes

2013 ◽  
Vol 745-746 ◽  
pp. 239-242
Author(s):  
Xing Pin Chen ◽  
Meng Liu ◽  
Xiao Wei Yu ◽  
Ming Ya Li
Keyword(s):  
Heat Treatment ◽  
Phase Formation ◽  
Microstructure Evolution ◽  
Significant Influence ◽  
Sintering Temperature ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Different Temperatures ◽  
Sintering Conditions ◽  
Powder In Tube

Effect of sintering conditions in the first heat treatment on the phase and microstructure evolution of Bi-2223/Ag/Ni composite-sheathed tapes fabricated by powder-in-tube method was studied. Samples were sintered at different temperatures for different time in an atmosphere of 14.5% O2. The results showed that this higher O2 atmosphere improved the content of Bi-2223 phase. XRD and SEM results showed that Bi-2223 content increased with the extension of the dwelling time. Meanwhile, the sintering temperature had significant influence on the Bi-2223 content and secondary phase dimensions as well. With the increase of the sintering temperature, the Bi-2223 content reached to a maximum at 834. With further increase of sintering temperature, the Bi-2223 phase was decomposed to Bi-2212 and others secondary phases.

Microstructure and Corrosion Properties of Mg-Zn-Ca-Zr Alloy for Biomedical Application

2013 ◽  
Vol 790 ◽  
pp. 11-15
Author(s):  
Dong Mei Jiang ◽  
Tang Sheng Yu ◽  
Dong Hua Jiang ◽  
Liang Guo ◽  
Zhan Yi Cao
Keyword(s):  
Solid Solution ◽  
Volume Fraction ◽  
Biomedical Application ◽  
Secondary Phase ◽  
Secondary Phases ◽  
Corrosion Properties ◽  
Lower Volume Fraction ◽  
Lower Volume ◽  
Fine Microstructure ◽  
Zr Alloy

The microstructuresandcorrosion properties of the as-cast Mg-Zn-Ca-Zralloys were investigated in this study. The results showed that the alloy was mainly composed of -Mg solid solution,Zr particle and the secondary phase of Ca2Mg6Zn3. The grain size of alloy specimens decreased with the increment of Zr content. The corrosion resistances were found to increase from 0.3% to 0.5% and then decrease from 0.5% to 0.7%. The Mg-4Zn-0.5Ca-0.5Zr had the best corrosion resistance in SBF solution.This was attributed to a combination of (1) the uniform and fine microstructure of alloy, (2) continuous distributions of the secondary phases, and (3) a lower volume fraction of Zr particles.

scholarly journals Current Development in Lead-FreeBi0.5(Na,K)0.5TiO3-Based Piezoelectric Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Ngo Duc Quan ◽  
Luong Huu Bac ◽  
Duong Van Thiet ◽  
Vu Ngoc Hung ◽  
Dang Duc Dung
Keyword(s):  
Solid Solution ◽  
Piezoelectric Properties ◽  
Domain Switching ◽  
Piezoelectric Materials ◽  
Secondary Phase ◽  
Lead Free ◽  
Secondary Phases ◽  
Current Development ◽  
Cubic Phases

The lead-free piezoelectric ceramics display good piezoelectric properties which are comparable with Pb(Zr,Ti)O3(PZT) and these materials overcome the hazard to the environment and human health. The Bi0.5(Na,K)0.5TiO3(BNKT) is rapidly developed because of good piezoelectric, ferroelectric, and dielectric properties compared to PZT. The origin of giant strain of BNKT piezoelectric materials was found at morphotropic phase boundary due to crystal change from tetragonal to orthorhombic and/or precipitation of cubic phases, in addition to domain switching mechanism. The dopants or secondary phases withABO3structure as solid solution are expected to change the crystal structure and create the vacancies which results in enhancement of the piezoelectric properties. In this work, we reviewed the current development of BNKT by dopants and secondary phase as solid solution. Our discussion will focus on role of dopants and secondary phase to piezoelectric properties of BNKT. This result will open the direction to control the properties of lead-free piezoelectric materials.

Pb-doped Bi-2212: Homogeneity Area, Oxidation and Effect on jc

2000 ◽  
Vol 659 ◽  
Author(s):  
A. Veresov ◽  
M. Pulkin ◽  
A. Knotko ◽  
V. Putlayev ◽  
E. K. H. Salje
Keyword(s):  
Solid Solution ◽  
Beneficial Effect ◽  
Oxygen Partial Pressure ◽  
Solid Solutions ◽  
Strong Evidence ◽  
Supersaturated Solid Solution ◽  
Secondary Phases ◽  
Different Temperatures ◽  
Two Stages ◽  
Pb Doping

ABSTRACTThe most promising way to improve jc in superconductors is likely to be a creation of small precipitates in the material during decomposition of supersaturated solid solution. It was recognised recently that Pb-doping of 2212 could have beneficial effect on jc. Bi2.1−xPbxSr2CaCu2O8+d (x=0.1…0.7) was prepared at different temperatures and oxygen partial pressure (pO2=10−3 – 0.21 atm) via nitrate route. The effect of pO2 and Pb-doping on Bi-2212 phase formation was explored with XRD, SEM/EPMA and TEM/SAED. The limit of Pb solubility in Bi-2212 was found to increase with a decrease in pO2 and corresponded to a decrease in x=0.3 at pO2 = 0.21 atm (850 °C) and x=0.6 at pO2 ∼ 10−3 atm (750 °C). TEM study of the as-synthesized solid solutions revealed significant nanoscale inhomogeneity attributed to Pb-segregation. For the samples with x > 0.3 the inhomogeneity quite often looked like a well- ordered wave with the period of about 10 nm. The samples of (Bi,Pb)-2212 processed under pO2 conditions were oxidized at 600–750°C in air for 0.5–60 h in order to cause precipitation of secondary phases from the supersaturated solid solution. Thermogravimetrical study (TG) of the oxidation gave a strong evidence of two stages composing the process. It was found that jc was enhanced by a factor of 2 after annealing at 650°C (i.e. during the first stage of oxidation).

Heat Treatment Studies on 50CrV4 Spring Steel

2015 ◽  
Vol 830-831 ◽  
pp. 139-142 ◽  
Author(s):  
V. Anil Kumar ◽  
M.K. Karthikeyan ◽  
R.K. Gupta ◽  
P. Ramkumar ◽  
M. Uday Prakash
Keyword(s):  
Room Temperature ◽  
Lath Martensite ◽  
Impact Resistance ◽  
Spring Steel ◽  
Delta Ferrite ◽  
Heat Treated ◽  
High Fatigue ◽  
Different Temperatures ◽  
Heat Treated Condition ◽  
Modulus Of Resilience

50CrV4 spring steel is a tough, shock resisting, shallow hardening chromium vanadium steel having high fatigue and impact resistance in the heat treated condition. It is used extensively in gears, pinions, springs, shafts, axles, pins, bolts, etc., which require high modulus of resilience. The alloy was realised through conventional melt route of electric arc furnace (EAF) followed by ESR. The application of the alloy is limited to a section thickness of 15mm [1]. Hence obtaining optimum mechanical properties becomes a challenging task. In this study, the hardening as well as tempering operations were limited to 15mm thickness. The samples from the alloy were subjected to hardening at 860°C for 1.25 h. and oil quenching to room temperature followed by tempering at four different temperatures of 250, 300, 370 & 450°C for 3 h. each with oil quenching to room temperature. It was found that the alloy exhibited good combination of strength and ductility when tempered at 450°C. Microstructural study revealed the presence of fine tempered lath martensite along with the presence of a very small amount of delta ferrite along prior austenitic grain boundaries.

LOW CYCLE FATIGUE BEHAVIOR AND LIFE PREDICTION OF A CAST COBALT-BASED SUPERALLOY

2012 ◽  
Vol 06 ◽  
pp. 251-256
Author(s):  
HO-YOUNG YANG ◽  
JAE-HOON KIM ◽  
KEUN-BONG YOO
Keyword(s):  
Fatigue Life ◽  
Strain Energy ◽  
Life Prediction ◽  
Prediction Models ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Total Strain ◽  
Cycle Fatigue ◽  
Total Strain Range ◽  
Different Temperatures

Co -base superalloys have been applied in the stationary components of gas turbine owing to their excellent high temperature properties. Low cycle fatigue data on ECY-768 reported in a companion paper were used to evaluate fatigue life prediction models. In this study, low cycle fatigue tests are performed as the variables of total strain range and temperatures. The relations between plastic and total strain energy densities and number of cycles to failure are examined in order to predict the low cycle fatigue life of Cobalt-based super alloy at different temperatures. The fatigue lives is evaluated using predicted by Coffin-Manson method and strain energy methods is compared with the measured fatigue lives at different temperatures. The microstructure observing was performed for how affect able to low-cycle fatigue life by increasing the temperature.

scholarly journals Effects of Different Solid Solution Temperatures on Microstructure and Mechanical Properties of the AA7075 Alloy After T6 Heat Treatment

2019 ◽  
Vol 38 (2019) ◽  
pp. 892-896 ◽  
Author(s):  
Süleyman Tekeli ◽  
Ijlal Simsek ◽  
Dogan Simsek ◽  
Dursun Ozyurek
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid Solution ◽  
Tensile Strength ◽  
Tensile Tests ◽  
Solution Temperature ◽  
T6 Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
Different Temperatures

AbstractIn this study, the effect of solid solution temperature on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment was investigated. Following solid solution at five different temperatures for 2 hours, the AA7075 alloy was quenched and then artificially aged at 120∘C for 24 hours. Hardness measurements, microstructure examinations (SEM+EDS, XRD) and tensile tests were carried out for the alloys. The results showed that the increased solid solution temperature led to formation of precipitates in the microstructures and thus caused higher hardness and tensile strength.

scholarly journals Influence of the microstructure on the cyclic stress-strain behaviour and fatigue life in hypo-eutectic Al-Si-Mg cast alloys

2018 ◽  
Vol 165 ◽  
pp. 15004 ◽  
Author(s):  
Jochen Tenkamp ◽  
Alexander Koch ◽  
Stephan Knorre ◽  
Ulrich Krupp ◽  
Wilhelm Michels ◽  
...  
Keyword(s):  
Solid Solution ◽  
Fatigue Life ◽  
Cyclic Loading ◽  
Weight Ratio ◽  
Cyclic Stress ◽  
Stress Strain ◽  
Strain Behaviour ◽  
Eutectic Morphology ◽  
Cast Alloys ◽  
Incremental Step

Aluminium alloys are promising candidates for energy-and cost-efficient components in automotive and aerospace industries, due to their excellent strength-to-weight ratio and relatively low cost compared to titanium alloys. As modern cast processing and post-processing, e.g. hot isostatic pressing, result in decreased frequency and size of defects, the weakest link depends on microstructural characteristics, e.g. secondary dendrite arm spacing (SDAS), Si eutectic morphology and α-Al solid solution hardness. Hereby, fatigue investigations of the effect of the microstructure characteristics on the cyclic stress-strain behaviour as well as fatigue mechanisms in the low cycle and high cycle fatigue regime are performed. For this purpose, samples of the aluminium cast alloy EN AC-AlSi7Mg0.3 with different Si eutectic morphology and α-Al solid solution hardness were investigated. To compare the monotonic and cyclic stress-strain curves, quasistatic tensile tests and incremental step tests were performed on two microstructure conditions. The results show that the cyclic loading leads to a hardening of the material compared to monotonic loading. Based on damage parameter Woehler curves, it is possible to predict the damage progression and fatigue life for monotonic and cyclic loading in hypo-eutectic Al-Si-Mg cast alloys by one power law.

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