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%.

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.

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.

Influence of Heat-Treatment and Rolling Conditions on the Mechanical Warm Forming Properties of Twin-Roll Cast AZ31

2017 ◽  
Vol 746 ◽  
pp. 184-191 ◽  
Author(s):  
Franz Berge ◽  
Marie Moses ◽  
Rudolf Kawalla ◽  
Madlen Ullmann
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Hot Rolling ◽  
Tensile Deformation ◽  
Warm Forming ◽  
Efficient Production ◽  
Research Strategies ◽  
Component Design ◽  
Roll Casting ◽  
Twin Roll

Magnesium sheets are used for wide-ranging applications in the automotive sector. In contrast to conventional magnesium processing routes for strips, twin-roll casting (TRC) and hot rolling is a cost-efficient production process for magnesium strips and sheets. As part of previous research strategies, the optimization of the thermomechanical treatment of magnesium alloys has resulted in excellent mechanical properties for the component design. However, the previously determined results at room temperature cannot be correlated with the warm forming behaviour during the component production. This is due to different deformation mechanisms, which are active at various temperatures. For TRC material, there is a lack of knowledge about the influence of heat-treatment and rolling on the final mechanical properties at hot working temperatures. This article depicts the investigations done on the influence of heat-treatment and hot rolling conditions on the mechanical properties of AZ31 strips at tensile deformation temperatures of 20 °C and 300 °C.

The Effect of Heat Treatment on the Microstructure and Mechanical Properties of Multilayered Composites Welded by Explosion

2012 ◽  
Vol 535-537 ◽  
pp. 231-234 ◽  
Author(s):  
Elena A. Prikhodko ◽  
Ivan A. Bataev ◽  
Anatoliy A. Bataev ◽  
Vasily S. Lozhkin ◽  
Vjacheslav I. Mali ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Explosive Welding ◽  
Structural Changes ◽  
Austenitic Steels ◽  
Chemical Compositions ◽  
Thin Sheets ◽  
Complicated Structure ◽  
Multilayered Composites ◽  
Quenching And Tempering

The structure of composites formed by explosive welding of thin sheets of tool and austenitic steels was studied by structural analysis methods. It is shown that the quenching and tempering of composites leads to the formation of complicated structure containing, along with layers of dissimilar steels, layers with new chemical compositions. Due to the structural changes there is an 2-fold increasing of impact toughness.

Improvement of mechanical properties of a nanoaluminium alloy by precipitate strengthening

2012 ◽  
Vol 57 (3) ◽  
pp. 877-881 ◽  
Author(s):  
K. Wawer ◽  
M. Lewandowska ◽  
K.J. Kurzydłowski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Precipitation Strengthening ◽  
Post Processing ◽  
Heat Treated ◽  
Precipitate Strengthening

In the present study, severe plastic deformation (SPD) processing was combined with pre- and post processing heat treatment to investigate the possibility of synergic grain size and precipitation strengthening. Samples of 7475 alloy were solution heat treated and water quenched prior to hydrostatic extrusion (HE) which resulted in a grain refinement by 3 orders of magnitude, from 70 μm to about 70 nm. The extruded samples were subsequently aged at temperatures resulting in formation of nanoprecipitates.

scholarly journals Ultra-fine Equiaxed Grain Refinement and Improvement of Mechanical Properties of α+β Type Titanium Alloys by Hydrogenation, Hot Working, Heat Treatment and Dehydrogenation

1994 ◽  
Vol 35 (4) ◽  
pp. 266-272 ◽  
Author(s):  
Hirofumi Yoshimura ◽  
Kin’ichi Kimura ◽  
Masayuki Hayashi ◽  
Mitsuo Ishii ◽  
Toshihiro Hanamura ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Titanium Alloys ◽  
Grain Refinement ◽  
Hot Working ◽  
Alpha Beta ◽  
Equiaxed Grain

Heat Treatment Selection and Forming Strategies for 6082 Aluminum Alloy

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Andrea Aginagalde ◽  
Xabier Gomez ◽  
Lander Galdos ◽  
Carlos García
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Deformation ◽  
High Strength ◽  
Point Of View ◽  
Forming Process ◽  
Annealed Condition ◽  
Heat Treated ◽  
Structural Parts ◽  
6082 Aluminum Alloy

Aluminum 6XXX alloys show high strength to weight ratios and are thus promising materials for today’s transport industry lightweight construction efforts. When considering both deformation and final mechanical properties, high ductility is interesting from the conformability point of view. On the other hand, high resistance is necessary in the automotive structural parts (which can be obtained through T6 precipitation heat treatment) but leads to reduced ductility. In order to increase aluminum alloys’ formability, warm forming is commonly applied. In contradiction to this, this article shows how the tensile deformation behavior of the 6082 T6 alloy is not affected by the temperature. In this work, the necessary formability values to obtain the parts are achieved, deforming the material under O annealed condition. But this strategy is focused on the formability perspective; therefore, the final mechanical properties do not achieve the necessary strength requirements. As a solution, the possibility of applying the T6 heat treatment after forming the parts (in annealed condition) is studied. A tensile characterization of the post-heat-treated specimens obtained from the deformed experimental part results in high flow stress levels, and thus, the strategy is validated. Nevertheless, the heat treatment leads to geometrical distortions in the final part, and thus, a last calibration step should be added to the forming process in order to obtain the desired shape.

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