Influence of Solution Treatment on Microstructure and Quench Cracking in a Water-Quenched Aluminium Alloy 7150

2010 ◽  
Vol 654-656 ◽  
pp. 934-937 ◽  
Author(s):  
Dao Kui Xu ◽  
Paul A. Rometsch ◽  
Hua Chen ◽  
Barry C. Muddle
Keyword(s):  
Crack Propagation ◽  
Solution Treatment ◽  
Single Step ◽  
Constituent Particle ◽  
Propagation Mode ◽  
Al Alloy ◽  
Triple Junctions ◽  
Quench Temperature ◽  
Quench Cracking ◽  
Cracking Mode

In this work, the influence of multi-step solution (MSS) treatments on the constituent particle dissolution, overheating and associated quench cracking behaviour in room temperature water-quenched 7150 Al alloy has been investigated. For comparison, the microstructure and quench cracking behaviour of single step solution treated samples water-quenched from 505°C were also investigated. Based on optical microscopy of differently quenched samples, the quench cracking mode and the influence of overheating of constituents on the quench cracking behaviour have been demonstrated. The results reveal that the constituent particles can be effectively dissolved in the MSS-505°C samples. When the quench temperature of MSS-505°C samples is equal to or higher than 485°C , macro quench cracks can be clearly observed. Moreover, the density and length of the quench cracks increase with increasing quench temperature. Etched microstructures indicate that the quench crack propagation mode is intergranular. However, for samples directly heated to 505°C , typical overheating can be observed at the triple junctions and these regions preferentially act as crack propagation routes.

scholarly journals Tempforming as an Advanced Processing Method for Carbon Steels

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1566
Author(s):  
Anastasiya Dolzhenko ◽  
Rustam Kaibyshev ◽  
Andrey Belyakov
Keyword(s):  
Impact Toughness ◽  
Crack Propagation ◽  
Large Strain ◽  
High Strength ◽  
Close Relation ◽  
Carbon Steels ◽  
Processing Method ◽  
Propagation Mode ◽  
Displacement Curve ◽  
The Impact

The microstructural mechanisms providing delamination toughness in high-strength low-alloyed steels are briefly reviewed. Thermo-mechanical processing methods improving both the strength and impact toughness are described, with a close relation to the microstructures and textures developed. The effect of processing conditions on the microstructure evolution in steels with different carbon content is discussed. Particular attention is paid to tempforming treatment, which has been recently introduced as a promising processing method for high-strength low-alloyed steel semi-products with beneficial combination of strength and impact toughness. Tempforming consists of large strain warm rolling following tempering. In contrast to ausforming, the steels subjected to tempforming may exhibit an unusual increase in the impact toughness with a decrease in test temperature below room temperature. This phenomenon is attributed to the notch blunting owing to easy splitting (delamination) crosswise to the principle crack propagation. The relationships between the crack propagation mode, the delamination fracture, and the load-displacement curve are presented and discussed. Further perspectives of tempforming applications and promising research directions are outlined.

scholarly journals Progressive Failure and Acoustic Emission Characteristics of Red Sandstone with Different Geometry Parallel Cracks under Uniaxial Compression Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xizhen Sun ◽  
Fanbao Meng ◽  
Ce Zhang ◽  
Xucai Zhan ◽  
He Jiang
Keyword(s):  
Acoustic Emission ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Geometric Distribution ◽  
Progressive Failure ◽  
Fractured Rock ◽  
Propagation Mode ◽  
Wing Crack ◽  
Red Sandstone ◽  
Parallel Cracks

The geometric distribution of initial damages has a great influence on the strength and progressive failure characteristics of the fractured rock mass. Initial damages of the fractured rock were simplified as parallel cracks in different geometric distributions, and then, the progressive failure and acoustic emission (AE) characteristics of specimens under the uniaxial compression loading were analyzed. The red sandstone (brittle materials) specimens with the parallel preexisting cracks by water jet were used in the tests. The energy peak and stress attenuation induced by the energy release of crack initiation were intuitively observed in the test process. Besides, three modes of rock bridge coalescence were obtained, and wing crack was the main crack propagation mode. The wing crack and other cracks were initiated in different loading stages, which were closely related to the energy level of crack initiation. The propagation of wing crack (stable crack) consumed a large amount of energy, and then, the propagation of shear crack, secondary crack, and anti-wing crack (unstable crack) was inhibited. The relationship between the crack propagation mode and the geometric distribution of existing cracks in the specimen was revealed. Meanwhile, the strength characteristic and failure mode of fractured rock with the different geometric distributions of preexisting crack were also investigated. The energy evolution characteristics and crack propagation were also analyzed by numerical modeling (PFC2D).

LOW CYCLE FATIGUE BEHAVIOR OF Zn-22Al ALLOY IN SUPERPLASTIC REGION AND NON-SUPERPLASTIC REGION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5477-5482 ◽  
Author(s):  
ATSUMICHI KUSHIBE ◽  
TSUTOMU TANAKA ◽  
YORINOBU TAKIGAWA ◽  
KENJI HIGASHI
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Crack Tip ◽  
The Other ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Secondary Cracks

The crack propagation properties for ultrafine-grained Zn -22 wt % Al alloy during low cycle fatigue (LCF) in the superplastic region and the non-superplastic region were investigated and compared with the corresponding results for several other materials. With the Zn - 22 wt % Al alloy, it was possible to conduct LCF tests even at high strain amplitudes of more than ±5%, and the alloy appeared to exhibit a longer LCF lifetime than the other materials examined. The fatigue life is higher in the superplastic region than in the non-superplastic region. The rate of fatigue crack propagation in the superplastic region is lower than that in the other materials in the high J-integral range. In addition, the formation of cavities and crack branching were observed around a crack tip in the supereplastic region. We therefore conclude that the formation of cavities and secondary cracks as a result of the relaxation of stress concentration around the crack tip results in a reduction in the rate of fatigue crack propagation and results in a longer fatigue lifetime.

scholarly journals Study of the Fracture Behavior of Tetragonal Zirconia Polycrystal with a Modified Phase Field Model

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4430 ◽  
Author(s):  
Jingming Zhu ◽  
Jun Luo ◽  
Yuanzun Sun
Keyword(s):  
Phase Transformation ◽  
Crack Propagation ◽  
Phase Field ◽  
Fracture Behavior ◽  
Tetragonal Zirconia ◽  
Finite Size ◽  
Phase Field Model ◽  
Crack Tip ◽  
Propagation Mode ◽  
Tetragonal Zirconia Polycrystal

The superior fracture toughness of zirconia is closely correlated with stress-induced martensitic phase transformation around a crack tip. In this study, a modified phase field (PF) model coupling phase transformation and fracture is proposed to study the fracture behavior and toughening effect of tetragonal zirconia polycrystal (TZP). The stress-induced tetragonal to monoclinic (t–m) phase transformation around a static or propagating crack is characterized with PF simulations. It is shown that the finite size and shape of the transformation zone under different loads and ambient temperatures can be well predicted with the proposed PF model. The phase transformation may decrease the stress level around the crack tip, which implies the toughening effect. After that, crack propagation in TZP is studied. As the stress field is perturbed by the phase transformation patterns, the crack may experience deflection and branching in the propagation process. It is found that the toughness of the grain boundaries (GBs) has important influences on the crack propagation mode. For TZP with strong GBs, the crack is more likely to propagate transgranularly while, for TZP with weak GBs, intergranular crack propagation is prevalent. Besides that, the crystal orientation and the external load can also influence the topology of crack propagation.

Corrosion behavior of heat-treated and cryorolled Al 5052 alloys in different chloride ion concentrations

2020 ◽  
Vol 67 (1) ◽  
pp. 7-15 ◽  
Author(s):  
Anasyida Abu Seman ◽  
Ji Kit Chan ◽  
Muhammad Anas Norazman ◽  
Zuhailawati Hussain ◽  
Dhindaw Brij ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Behaviour ◽  
Solution Treatment ◽  
Chloride Ion ◽  
Optical Microscope ◽  
Al Alloy ◽  
Content Type ◽  
Ion Concentrations ◽  
Heat Treated ◽  
Chloride Environment

Purpose This paper aims to investigate the corrosion behaviour of heat-treated and cryorolled Al 5052 alloys in different Cl− ion concentrations. Design/methodology/approach NaCl solutions with concentrations of 0, 0.5, 3.5 and 5.5 per cent were selected. Samples were subjected to pre-heat treatment (annealing at 300 °C and solution treatment at 540 °C) and cryorolling up to 30 per cent reduction before undergoing corrosion tests. The corrosion behaviour of the samples was then investigated by potentiodynamic polarization. The microstructure of the corroded samples was evaluated under an optical microscope, and the percentages of pits on their surfaces were calculated. Findings The cryorolled samples had a lower corrosion rate than the samples that were not cryorolled. The cryorolled sample that underwent solution treatment showed the highest corrosion resistance among all the samples tested. Practical implications The commercial impact of the study is the possibility of using the cryorolled Al alloy in various ion chloride environment. Originality/value The obtained results help in understanding the corrosion behaviour of cryorolled samples under different heat treatment conditions.

Effect of Solution Treatment Temperature on Microstructure and Mechanical Properties of Al-5.1Zn-2Mg-0.1Ti (wt. %) Produced by Squeeze Casting

2018 ◽  
Vol 939 ◽  
pp. 38-45 ◽  
Author(s):  
Risly Wijanarko ◽  
Irene Angela ◽  
Bondan Tiara Sofyan
Keyword(s):  
Squeeze Casting ◽  
Volume Fraction ◽  
Solution Treatment ◽  
Treatment Temperature ◽  
Ageing Process ◽  
Al Alloy ◽  
Second Phase ◽  
Solution Treatment Temperature ◽  
Phase Volume Fraction ◽  
Ti Addition

Al 7xxx alloy is a heat treatable Al alloy with superior strength. Solution treatment in precipitation hardening sequence of the alloy has an important role to dissolve second phases and bring vacancies out to form precipitates in the ageing process. Another strengthening can be done by Ti addition as grain refiner. As cast alloy by squeeze casting was homogenized at 400 °C for 4 h. Solution treatment was conducted at 220, 420, and 490 °C, followed by rapid quenching. Subsequent ageing was conducted at 130 °C for 48 h. Characterization was performed by optical microscope, SEM-EDS (Scanning Electron Microscopy – Energy Dispersive Spectroscopy), Rockwell hardness testing, XRD (X-Ray Diffraction), and STA (Simultaneous Thermal Analysis). Ti added alloy showed rounder grains, lower hardness, and more reduction in second phase volume fraction along with increasing solution treatment temperature than those in alloys without Ti addition. Otherwise, the alloy final hardness was increasing and higher after the ageing process due to higher second phase dissolution which leads to more precipitates formed.

Effect of Double-Step Solution Treatment on Rejuvenation Heat Treated Microstructure of IN-738 Superalloy

2020 ◽  
Vol 856 ◽  
pp. 36-42
Author(s):  
Chuleeporn Paa-Rai
Keyword(s):  
Heat Treatment ◽  
Image Analysis ◽  
Electron Microscope ◽  
Solution Treatment ◽  
Single Step ◽  
Double Step ◽  
Heat Treated ◽  
Cast Superalloy ◽  
Scanning Electron

This work investigates the effect of rejuvenation heat treatment, with double-step solution treatment at the temperature from 1150 °C to 1200 °C, on the recovered microstructure of IN-738 cast superalloy. The superalloy has been long-term exposed as a turbine blade in a gas turbine prior to this study. After double solution treatment and aging at 845 °C for 12 h and 24 h, the recovered microstructures were examined by using a scanning electron microscope. Coarse γ΄ particles, that have presented in damaged microstructures, could not be observed in the samples after the rejuvenation heat treatment. In addition, the image analysis illustrates that the reprecipitated γ΄ particles in the samples with double-step solution treatments increase significantly in sizes during aging than that in the samples with the single-step solution treatment. Furthermore, the measurement of the samples hardness presents that the as-receive sample hardness is improved after rejuvenation heat treatment studied in this work.

scholarly journals The formation mechanism of the lamellar phase precipitated during solid solution treatment in the Mg-Gd-Al alloy

2020 ◽  
Vol 9 (5) ◽  
pp. 11392-11401
Author(s):  
Yongpeng Zhuang ◽  
Pengwen Zhou ◽  
Hongxia Wang ◽  
Kaibo Nie ◽  
Yiming Liu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Formation Mechanism ◽  
Solution Treatment ◽  
Lamellar Phase ◽  
Al Alloy ◽  
Solid Solution Treatment
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