Precipitation Strengthening in AA7449 Aluminium Alloy: Understanding the Relationship between Microstructure, Yield Strength and Strain Hardening

2006 ◽  
Vol 519-521 ◽  
pp. 991-996 ◽  
Author(s):  
G. Fribourg ◽  
Alexis Deschamps ◽  
Yves Bréchet
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Activation Volume ◽  
Rate Sensitivity ◽  
Work Hardening Rate ◽  
Deformation Step ◽  
Evolution Of Microstructure ◽  
Step Heat Treatment ◽  
The Relationship

This paper presents a detailed study of the microstructure and mechanical properties of AA7449 alloy during the two step heat treatment leading to the industrial T7651 temper. It is first shown that reproducing the heat treatment without a deformation step as used in the T7651 industrial temper leads to 2-fold decrease of the precipitation kinetics due to the absence of dislocations, while the resulting mechanical properties (if this change in kinetics is accounted for) are very similar. The work hardening rate is shown to strongly evolve during the heat treatment, and this evolution has been correlated to the evolution of microstructure using a Kocks-Mecking-Estrin analysis. Finally, an analysis in terms of activation volume of the strain rate sensitivity allows for the determination of the dislocation / precipitate interaction in the overaged temper.

Characterization of Microstructure and Mechanical Properties of 6060 Aluminum Alloy Processed by ECAP

2018 ◽  
Vol 275 ◽  
pp. 81-88
Author(s):  
Monika Karoń ◽  
Marcin Adamiak
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Internal Stresses ◽  
Refined Grains ◽  
Angular Pressing ◽  
Heat Treated ◽  
Evolution Of Microstructure

The purpose of this paper is to present the microstructure and mechanical behavior of 6060 aluminum alloy after intense plastic deformation. Equal Channel Angular Pressing (ECAP) was used as a method of severe plastic deformation. Before ECAP part of the samples were heat treated to remove internal stresses in the commercially available aluminium alloy. The evolution of microstructure and tensile strength were tested after 1, 3, 6 and 9 ECAP passes in annealed and non annealed states. It was found that intensely plastically deformed refined grains were present in the tested samples and exhibited increased mechanical properties. Differences were noted between samples without and after heat treatment

scholarly journals Effect of Post Processing Heat Treatment Routes on Microstructure and Mechanical Property Evolution of Haynes 282 Ni-Based Superalloy Fabricated with Selective Laser Melting (SLM)

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 629
Author(s):  
Anagh Deshpande ◽  
Subrata Deb Nath ◽  
Sundar Atre ◽  
Keng Hsu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Mechanical Property ◽  
High Temperature ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Step Heat Treatment ◽  
Microstructure And Mechanical Property ◽  
In Situ Heat Treatment

Selective laser melting (SLM) is one of the most widely used additive manufacturing technologies. Fabricating nickel-based superalloys with SLM has garnered significant interest from the industry and the research community alike due to the excellent high temperature properties and thermal stability exhibited by the alloys. Haynes-282 alloy, a γ′-phase strengthened Ni-based superalloy, has shown good high temperature mechanical properties comparable to alloys like R-41, Waspaloy, and 263 alloy but with better fabricability. A study and comparison of the effect of different heat-treatment routes on microstructure and mechanical property evolution of Haynes-282 fabricated with SLM is lacking in the literature. Hence, in this manuscript, a thorough investigation of microstructure and mechanical properties after a three-step heat treatment and hot isostatic pressing (HIP) has been conducted. In-situ heat-treatment experiments were conducted in a transmission electron microscopy (TEM) to study γ′ precipitate evolution. γ′ precipitation was found to start at 950 °C during in-situ heat-treatment. Insights from the in-situ heat-treatment were used to decide the aging heat-treatment for the alloy. The three-step heat-treatment was found to increase yield strength (YS) and ultimate tensile strength (UTS). HIP process enabled γ′ precipitation and recrystallization of grains of the as-printed samples in one single step.

Effect of Grain Refinement on Mechanical Properties in 25Cr-1N Austenitic Steel

2010 ◽  
Vol 638-642 ◽  
pp. 3549-3554 ◽  
Author(s):  
Toshihiro Tsuchiyama ◽  
T. Onomoto ◽  
K. Tsuboi ◽  
Setsuo Takaki
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stress Concentration ◽  
Grain Refinement ◽  
Intergranular Fracture ◽  
Tensile Deformation ◽  
Austenitic Steels ◽  
High Yield ◽  
Structure Characteristic ◽  
Step Heat Treatment

The Fe-25Cr-1N alloy produced by solution nitriding possesses extremely high yield strength owing to the solid solution strengthening by nitrogen. However, it was found that the steel exhibited an insufficient elongation because of the brittle intergranular fracture caused during the uniform tensile deformation. This is due to the marked stress concentration at grain boundaries, which is derived from the grain coarsening caused during long time solution nitriding and the development of planar dislocation structure characteristic of high nitrogen austenitic steels. The most effective way to reduce the stress concentration at grain boundary during deformation should be grain refinement. In this study, grain refinement was attempted by the two-step heat treatment for the Fe-25Cr-1N(-Mn) alloy, and then the mechanical properties were investigated by means of tensile tests and fatigue tests. The two-step heat treatment resulted in the grain refinement of austenite to 20 microns in diameter. The intergranular fracture was greatly suppressed from 70% (as-solution-nitrided) to 10% (grain-refined) in area fraction by the grain refinement. In addition, elongation was markedly increased with local necking. The yield stress and tensile strength were also increased, and thus, the fatigue limit is also raised by more than 30%.

Evolution of Microstructure and Mechanical Properties of the Thixo-Diecast 319s Alloy during Heat Treatment

2013 ◽  
Vol 765 ◽  
pp. 511-515 ◽  
Author(s):  
Da Quan Li ◽  
Xiao Kang Liang ◽  
Fu Bao Yang ◽  
You Feng He ◽  
Fan Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Alloy ◽  
Grain Structure ◽  
Precipitate Size ◽  
Fine Grain ◽  
Microstructure And Mechanical Properties ◽  
Optimum Heat ◽  
Evolution Of Microstructure

The evolution of microstructure and mechanical properties during solution and ageing heat treatment process was studied in terms of a thixo-diecast impeller of 319s aluminium alloy. The cast alloy exhibited a microstructure consisting of primary uniformly distributed in α-Al globules and the eutectics. A series of heat treatment studies were performed to determine optimum heat treatment parameters, in order to achieve fine grain structure, fine silicon particles and optimal precipitate size and distribution. Optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to study the evolution of microstructure and mechanical properties. The results demonstrate that, the full T6 heat treatments are successfully applied to thixo-diecast 319s impellers. A two-step solution heat treatment is employed to prevent porosity due to overheating. The tensile properties of thixo-diecast 319s impellers were substantially enhanced after T6 heat treatment. The plate-shaped θ′ precipitates and lath-shaped Q′ precipitates are the most effective for precipitation strengthening.

Fabrication of Porous Polyethylene by Two-Stepped Heat Treatment and Powder Printing Technique

2010 ◽  
Vol 93-94 ◽  
pp. 165-168 ◽  
Author(s):  
Jintamai Suwanprateeb ◽  
Kitiya Wasoontararat ◽  
Waraporn Suvannapruk
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Density Polyethylene ◽  
Physical And Mechanical Properties ◽  
High Density ◽  
Processing Conditions ◽  
Structure And Properties ◽  
Porous Polyethylene ◽  
Printing Technique ◽  
The Relationship

In this study, a combination of powder printing technique and two-stepped heat treatment was utilized as a mean to prepare porous high density polyethylene structure. Physical and mechanical properties of the resulting structure were then characterized by porosity measurement and monotonic tensile test. It was found that the relationship between structure and properties was strongly influenced by processing conditions including compositions, treatment times and treatment temperatures. This process could increase the properties of porous high density polyethylene significantly over the single-stepped heat treatment without destroying porous structure. Porous high density polyethylene bodies having a porosity ranging from 46-58 percents with tensile strength up to approximately 4 MPa could be successfully prepared in this study.

Weldability Investigation of Temper-Grade Steels

2008 ◽  
Vol 589 ◽  
pp. 31-35
Author(s):  
Gábor Lengyel ◽  
Béla Palotás
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Heat Conduction ◽  
Heat Affected Zone ◽  
Three Dimensional ◽  
Cold Cracking ◽  
Crucial Importance ◽  
Preheat Temperature ◽  
Wide Range

The mechanical properties of temper-grade steels can be modified in a wide range by heat treatment. The principle of heat treatment lies in the good hardenability, so when such steels are welded it is very likely that the heat affected zone is hardened. Considering the fact that in the case of design simplifications it may be needed to weld temper-grade steels, as well therefore it is of crucial importance to eliminate cold cracking. There are many methods available to determine preheat temperature. The applicability of methods for determination of preheat temperature was checked by experimental welding for both two and three dimensional heat conduction. According to our experience the different methods cannot be applied in general namely they are valid only under certain conditions.

Sign in / Sign up

Export Citation Format

Share Document