Modeling the Microstructural and Yield Strength Evolution of an Age-Hardenable Al Alloy for High Temperature Applications

2016 ◽  
Vol 879 ◽  
pp. 380-385 ◽  
Author(s):  
Marco Colombo ◽  
Elisabetta Gariboldi ◽  
Paola Bassani ◽  
Mihaela Albu ◽  
Ferdinand Hofer
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Yield Strength ◽  
Elevated Temperatures ◽  
Age Hardening ◽  
Homogeneous Distribution ◽  
Al Alloy ◽  
Physically Based ◽  
The Matrix ◽  
Physically Based Models

The mechanical properties of Al alloys are strongly affected by their microstructure: the size and shape of precipitates, their homogeneous distribution and their coherency with the matrix are of primary importance for an effective strengthening of the alloys at room and elevated temperatures. Physically-based models are powerful tools to predict the influence of the mentioned parameters on the mechanical properties of the alloy after age hardening, and also to predict the effect of high temperature service conditions on microstructure evolution. Scope of this work is to model the dimensional kinetic evolution of plate shaped precipitates of an Al-based alloy during aging and after different overaging times at elevated temperature, and use these results to estimate the alloy yield strength. The alloy strengthening response is due to three terms, linearly summed: the intrinsic strength of Aluminum, the contribution from solute in solid solution and the contribution arising from precipitates. The consistency of the model is verified with experimental data obtained from a 2014 Al alloy.

Investigation on the Microstructure and Mechanical Properties of T23 Steel during High Temperature Aging

2020 ◽  
Vol 993 ◽  
pp. 575-584
Author(s):  
Bao Liang Shi ◽  
Chao Zhang ◽  
Yao Wen Tang ◽  
Guo Jie Wei ◽  
Yan Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
High Temperature ◽  
Yield Strength ◽  
Aging Time ◽  
Size Increase ◽  
Microstructure And Mechanical Properties ◽  
The Matrix ◽  
High Temperature Aging ◽  
Temperature Aging

The changes of the microstructure and mechanical properties of T23 steel were investigated during high temperature aging at 625 °C up to 3000 h. The results showed that the bainitic lath microstructure first decreased and then totally disappeared with the increase of aging time, the size of the carbides gradually increased and the recovery occurred after aging for 1000 h. The contents of W, Mo elements in the matrix after aging for 3000 h were remarkably decreased by 27.6% and 45% compared with the as-received state. However, no M6C carbides formed in spite of the obvious desolution transformation of W, Mo. Both the yield strength and the tensile strength at room and high temperature were decreased with the increase of aging time at 625 °C, and the tensile strength at high temperature after aging for 3000 h exhibited the largest of decline compared with the as-received state. The main reasons for the decrease of the mechanical properties related to the microstructure variations, such as the size increase of the M23C6 carbides, the dissolution of the bainite lath microstructure and the occurrence of the recovery. Meanwhile, the desolution of W, Mo elements plays an important role in the decrease of the mechanical properties.

Effects of Gadolinium on Aging Behavior and Mechanical Properties of Mg-5Y-3Nd-Zr Alloy

2011 ◽  
Vol 295-297 ◽  
pp. 1183-1187
Author(s):  
Li Dong Wang ◽  
Cheng Yao Xing ◽  
Xiu Li Hou ◽  
Yao Ming Wu ◽  
Jian Fei Sun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Morphology ◽  
Age Hardening ◽  
Peak Hardness ◽  
Homogeneous Distribution ◽  
Aging Behavior ◽  
The Matrix ◽  
Cast Alloys ◽  
Mould Casting ◽  
Zr Alloy

Mg-5Y-3Nd-Zr-xGd (x=0 and 4 wt.%) alloys were prepared by metal mould casting, and aging behavior, mechanical properties and fracture morphology were investigated. The result shows that after T6 treatment, the massive eutectic phase in as-cast alloys dissolved and finer Mg5RE phase precipitated dispersively in the matrix, and mechanical properties were improved simultaneously. Mg-5Y-3Nd-4Gd-Zr alloy exhibits good age hardening behavior and the peak hardness is about 20% higher than the Gd-free alloy. Gd addition can significantly improve mechanical properties of the alloy especially at the elevated temperature. The ultimate tensile strength and yield strength of Mg-5Y-3Nd-4Gd-Zr alloy at 250°C, with the value of 276 and 168 MPa, respectively, are over 20% higher than those of the Gd-free alloy. It is mainly attributed to the increase and homogeneous distribution of the fine heat-resistant Mg5RE precipitate in the matrix.

MECHANICAL PROPERTIES OF STRUCTURAL STEEL AND HIGH-TENSION BOLT AT ELEVATED TEMPERATURE

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Kyung-Jae Shin ◽  
Hee-Du Lee ◽  
So-Yeong Kim ◽  
Da-Som Chu ◽  
Jong-Hun Woo
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Yield Strength ◽  
Structural Steel ◽  
Elevated Temperatures ◽  
Residential Buildings ◽  
Tensile Force ◽  
Test Results ◽  
Steel Members ◽  
Reduction Factors

This paper presents the test results of the mechanical properties of three types of structural steel at high temperature, which are generally used for the Pre-Engineered Building (PEB) system. The PEB system is generally used for non-residential buildings, such as factories and warehouses. The structural steel members are installed without fire resistance protection, which means they are very weak in the case of fire. The end-plate connection could be critical in the case of fire because most of the moment is resisted by the tensile force of the bolts. Therefore, the mechanical properties of bolts at elevated temperatures are tested. Coupon test specimens for SS400(SS275), SM490(SS355), and F10T bolts were tested according to ASTM E8M. The high-temperature coupon tests were performed at 20°C, 400°C, 500°C, 600°C, 700°C, and 800°C. The test results were compared with the design reduction factors obtained from the American and European standards. The yield strength and tensile strength satisfied the minimum strength of the specified standards at 20°C. However, the reduction factor for yield strength obtained at a high temperature was lower than that of the standard value suggested by the code. In particular, the reduction factors for the high-strength bolt (F10T) were lower than those of the structural steel members (SS400(SS275), SM490(SM355)).

Effects of Quenching Rate on the Microstructures and Mechanical Properties of the Heat Treatable Mg-4.2Y-2.3Nd-1.0Gd-0.6Zr Magnesium Alloy

2015 ◽  
Vol 816 ◽  
pp. 356-361
Author(s):  
Y.H. Kang ◽  
D. Wu ◽  
Rong Shi Chen ◽  
E.H. Han
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Vickers Hardness ◽  
Cast Alloy ◽  
Age Hardening ◽  
Quenching Rate ◽  
Sand Cast ◽  
Quench Sensitivity ◽  
The Matrix ◽  
Microstructures And Mechanical Properties

The effects of quenching rate on the microstructures and mechanical properties of the heat treatable Mg-4.2Y-2.3Nd-1.0Gd-0.6Zr (wt.%) (WE43) sand-cast alloy have been studied using a combination of mechanical testing, Vickers hardness testing, optical microscopy (OM) and scanning electron microscope (SEM). Two quenching conditions, either air quenching or 60°C water quenching, were employed. The results indicate that some precipitates have formed in the matrix and grain boundaries in the air-quenched solutionized alloy. And the Vickers hardness and yield strength (YS) is HV77 and 155 MPa, respectively, which is slightly more than the 60°C water-quenched solutionized alloy. However, the ultimate tensile strength (UTS) and yield strength (YS) of the peak-aged at 250°C (T6) of the two quenching conditions are both 273 MPa and 212 MPa, respectively. And they have similar age hardening curves at 250°C and the T6 microstructure. So the results indicate that in this work of quenching rate range WE43 alloy has few quench sensitivity effect.

scholarly journals Effect of Pre-Stretch on the Precipitation Behavior and the Mechanical Properties of 2219 Al Alloy

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2101
Author(s):  
Guo-Ai Li ◽  
Zheng Ma ◽  
Jian-Tang Jiang ◽  
Wen-Zhu Shao ◽  
Wei Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
High Strength ◽  
Age Hardening ◽  
Al Alloy ◽  
Precipitation Behavior ◽  
Scanning Calorimetry ◽  
Transmission Electron ◽  
Lower Temperature ◽  
Age Strengthening

The influence of pre-stretch on the mechanical properties of 2219 Al alloys sheets were systematically investigated, with the aim of examining the age-strengthening in parts draw-formed from as-quenched sheets. The precipitation was characterized based on differential scanning calorimetry (DSC) analysis and transmission electron microscope (TEM) observation of specimens of as-quenched and quenched-stretched condition to address the influence of pre-stretching. A tensile test was performed to evaluate the effect on mechanical properties. The introduction of pre-stretching endues increased yield strength (YS) and thus can be helpful to exert the potential of the alloy. Peak YS of 387.5 and 376.8 MPa are obtained when specimens pre-stretched for 10% are aged at 150 and 170 °C, respectively, much higher than that obtained in the non-stretched specimens (319.2 MPa). The precipitation of Guinier-Preston zone (G.P. zones) and the transition to θ″ shifts to a lower temperature when pre-stretched is performed. The high density of dislocations developed during the stretching contributes to the acceleration in precipitation. Quench-stretched specimens present a much quicker age-hardening response at the beginning stage, which endue higher peaked yield strength. The yield strength, however, decrease much more quickly due to the recovery that occurs during the aging processes. The study suggested the feasibility of aging draw-formed components of 2219 Al alloy to obtain high strength.

scholarly journals Development of Precipitation-Strengthened Al0.8NbTiVM (M = Co, Ni) Light-Weight Refractory High-Entropy Alloys

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2085
Author(s):  
Kangjin Lee ◽  
Yunjong Jung ◽  
Junhee Han ◽  
Sung Hwan Hong ◽  
Ki Buem Kim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Single Phase ◽  
Elevated Temperatures ◽  
Critical Role ◽  
Mixing Enthalpy ◽  
Homogeneous Distribution ◽  
High Entropy Alloys ◽  
Light Weight ◽  
High Entropy

Single-phase solid-solution refractory high-entropy alloys (RHEAs) have been receiving significant attention due to their excellent mechanical properties and phase stability at elevated temperatures. Recently, many studies have been reported regarding the precipitation-enhanced alloy design strategy to further improve the mechanical properties of RHEAs at elevated temperatures. In this study, we attempted to develop precipitation-hardened light-weight RHEAs via addition of Ni or Co into Al0.8NbTiV HEA. The added elements were selected due to their smaller atomic radius and larger mixing enthalpy, which is known to stimulate the formation of precipitates. The addition of the Ni or Co leads to the formation of the sigma precipitates with homogeneous distribution. The formation and homogeneous distribution of sigma particles plays a critical role in improvement of yield strength. Furthermore, the Al0.8NbTiVM0.2 (M = Co, Ni) HEAs show excellent specific yield strength compared to single-phase AlNbTiV and NbTiVZr RHEA alloys and conventional Ni-based superalloy (Inconel 718) at elevated temperatures.

The effect of ageing duration on the mechanical properties of Al alloy 6061-garnet composites

2001 ◽  
Vol 215 (2) ◽  
pp. 113-119
Author(s):  
S C Sharma
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Al Alloy ◽  
Destructive Testing ◽  
Transmission Electron ◽  
Heat Treated ◽  
The Matrix ◽  
Reinforcing Particle ◽  
Alloy 6061

A well-consolidated composite of Al alloy 6061 reinforced with 4, 8 and 12 wt% garnet was prepared by a liquid metallurgy technique, the composite was heat treated for different ageing durations (T6 treatment), and its mechanical properties were determined by destructive testing. The results of the study indicated that, as the garnet particle content in the composites increased, there were marked increases in the ultimate tensile strength, compressive strength and hardness but there was a decrease in the ductility. There was an improvement in the tensile strength, compressive strength, and hardness with ageing due to precipitation. Precipitation in Al alloy 6061, with and without garnet particulate reinforcement, was studied using transmission electron microscopy. The fracture behaviour of the composites was altered significantly by the presence of garnet particles and the crack propagation through the matrix, and the reinforcing particle clusters resulted in final fracture.

scholarly journals Microstructure Characteristics and Strengthening Behavior of Cu-Bearing Non-Oriented Silicon Steel: Conventional Process versus Strip Casting

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1815
Author(s):  
Feng Fang ◽  
Diwen Hou ◽  
Zhilei Wang ◽  
Shangfeng Che ◽  
Yuanxiang Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
High Speed ◽  
Silicon Steel ◽  
Strip Casting ◽  
Precipitation Strengthening ◽  
Conventional Process ◽  
Core Losses ◽  
The Matrix ◽  
Bcc Structure

Based on conventional hot rolling processes and strip casting processes, Cu precipitation strengthening is used to improve the strength of non-oriented silicon steel in order to meet the requirements of high-speed driving motors of electric vehicles. Microstructure evolution was studied, and the effects of Cu precipitates on magnetic and mechanical properties are discussed. Compared with conventional processes, non-oriented silicon steel prepared by strip casting exhibited advantages with regard to microstructure optimization with coarse grain and {100} texture. Two-stage rolling processes were more beneficial for uniform microstructure, coarse grains and improved texture. The high magnetic induction B50 of 1.762 T and low core losses with P1.5/50, P1.0/400 and P1.0/1000 of 1.93, 11.63 and 44.87 W/kg, respectively, were obtained in 0.20 mm sheets in strip casting. Cu precipitates significantly improved yield strength over ~120 MPa without deteriorating magnetic properties both in conventional process and strip casting. In the peak stage aged at 550 °C for 120 min, Cu precipitates retained bcc structure and were coherent with the matrix, and the yield strength of the 0.20 mm sheet was as high as 501 MPa in strip casting. The main mechanism of precipitation strengthening was attributed to coherency strengthening and modulus strengthening. The results indicated that balanced magnetic and mechanical properties can be achieved in thin-gauge non-oriented silicon steel with Cu addition in strip casting.

scholarly journals Comparison of Mechanical and Microstructural Properties of as-Cast Al-Cu-Mg-Ag Alloys: Room Temperature vs. High Temperature

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1330
Author(s):  
Muhammad Farzik Ijaz ◽  
Mahmoud S. Soliman ◽  
Ahmed S. Alasmari ◽  
Adel T. Abbas ◽  
Faraz Hussain Hashmi
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Mechanical Testing ◽  
Tensile Testing ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Microstructural Properties ◽  
Testing Environments ◽  
Mechanical And Microstructural Properties ◽  
Mg Content

Unfolding the structure–property linkages between the mechanical performance and microstructural characteristics could be an attractive pathway to develop new single- and polycrystalline Al-based alloys to achieve ambitious high strength and fuel economy goals. A lot of polycrystalline as-cast Al-Cu-Mg-Ag alloy systems fabricated by conventional casting techniques have been reported to date. However, no one has reported a comparison of mechanical and microstructural properties that simultaneously incorporates the effects of both alloy chemistry and mechanical testing environments for the as-cast Al-Cu-Mg-Ag alloy systems. This preliminary prospective paper presents the examined experimental results of two alloys (denoted Alloy 1 and Alloy 2), with constant Cu content of ~3 wt.%, Cu/Mg ratios of 12.60 and 6.30, and a constant Ag of 0.65 wt.%, and correlates the synergistic comparison of mechanical properties at room and elevated temperatures. According to experimental results, the effect of the precipitation state and the mechanical properties showed strong dependence on the composition and testing environments for peak-aged, heat-treated specimens. In the room-temperature mechanical testing scenario, the higher Cu/Mg ratio alloy with Mg content of 0.23 wt.% (Alloy 1) possessed higher ultimate tensile strength when compared to the low Cu/Mg ratio with Mg content of 0.47 wt.% (Alloy 2). From phase constitution analysis, it is inferred that the increase in strength for Alloy 1 under room-temperature tensile testing is mainly ascribable to the small grain size and fine and uniform distribution of θ precipitates, which provided a barrier to slip by deaccelerating the dislocation movement in the room-temperature environment. Meanwhile, Alloy 2 showed significantly less degradation of mechanical strength under high-temperature tensile testing. Indeed, in most cases, low Cu/Mg ratios had a strong influence on the copious precipitation of thermally stable omega phase, which is known to be a major strengthening phase at elevated temperatures in the Al-Cu-Mg-Ag alloying system. Consequently, it is rationally suggested that in the high-temperature testing scenario, the improvement in mechanical and/or thermal stability in the case of the Alloy 2 specimen was mainly due to its compositional design.

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