Superplasticity of Friction-Stir Welded Al-Mg-Sc Alloy with Ultrafine-Grained Microstructure Obtained by Warm Severe Plastic Deformation

2016 ◽  
Vol 879 ◽  
pp. 2395-2400 ◽  
Author(s):  
Sergey Malopheyev ◽  
Sergey Mironov ◽  
Igor Vysotskiy ◽  
Rustam Kaibyshev
Keyword(s):  
Large Scale ◽  
Base Material ◽  
High Strength ◽  
Testing Temperature ◽  
Total Elongation ◽  
Friction Stir ◽  
Fine Grained ◽  
Angular Pressing ◽  
Elongation To Failure ◽  
Superplastic Properties

High-strength sheets of Al-5.4Mg-0.2Sc-0.1Zr alloy were produced by equal-channel angular pressing (ECAP) to 12 passes via route BC at 300 °C (573 K) followed by isothermal rolling at 300 °C (573 K) to a total thickness reduction of 80%. The final sheets with ultra-fine grained (UFG) structure were joined by friction stir welding (FSW). The tensile samples including all of the characteristic FSW microstructural zones were machined perpendicular to welding direction. The material demonstrated excellent superplastic properties in the range of temperatures from 350 (623 K) to 450 °C (723 K) at strain rates ranging from 8.3×10-3 s-1 to 3.3×10-1 s-1. The base material was found to be prone to abnormal grain growth at the testing temperature. This led to localization of the superplastic deformation in the stir zone section of the joints and thus limited total elongation-to-failure. The relationship between superplastic ductility and microstructure and application of this technique for the fabrication of large-scale superplastic sheets are discussed.

Superplastic Behavior of Friction-Stir Welded Joints of an Al-Mg-Sc Alloy with Ultrafine-Grained Microstructure

2016 ◽  
Vol 838-839 ◽  
pp. 338-343 ◽  
Author(s):  
Sergey Malopheyev ◽  
Sergey Mironov ◽  
Igor Vysotskiy ◽  
Rustam Kaibyshev
Keyword(s):  
Strain Rate ◽  
True Strain ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Friction Stir ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Superplastic Properties

The commercial Al-5.4Mg-0.2Sc-0.1Zr alloy was subjected to equal-channel angular pressing at 300°C to a true strain ~12 followed by cold rolling to a total thickness reduction of 80%. The ultrafine-grained sheets were joined by friction stir welding (FSW). To evaluate superplastic properties of the weldments, the tensile samples including all of the characteristic FSW microstructural zones were machined perpendicular to the welding direction and pulled up to failure in the temperature range of 400 to 500°C and at strain rates of 2.8×10-4 s-1 to 5.6×10-1 s-1. The friction-stir welded material exhibited excellent superplastic properties. The highest elongation-to-failure of ~1370% was recorded at a temperature of ~450°C and an initial strain rate of 5.6×10-2 s-1, where the strain rate sensitivity coefficient was about 0.64. The relationship between superplastic ductility and microstructure is discussed.

scholarly journals Increase in Total Elongation Caused by Pure Shear Deformation in Ultra-Fine-Grained Cu Processed by Equal-Channel Angular Pressing

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 654
Author(s):  
Ryosuke Matsutani ◽  
Nobuo Nakada ◽  
Susumu Onaka
Keyword(s):  
Shear Deformation ◽  
Equal Channel Angular Pressing ◽  
Pure Shear ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Total Elongation ◽  
Local Deformation ◽  
Image Correlation ◽  
Fine Grained ◽  
Angular Pressing

Ultra-fine-grained (UFG) Cu shows little total elongation in tensile tests because simple shear deformation is concentrated in narrow regions during the initial stage of plastic deformation. Here, we attempted to improve the total elongation of UFG Cu obtained by equal-channel angular pressing. By making shallow dents on the side surfaces of the plate-like specimens, this induced pure shear deformation and increased their total elongation. During the tensile tests, we observed the overall and local deformation of the dented and undented UFG Cu specimens. Using three-dimensional digital image correlation, we found that the dented specimens showed suppression of thickness reduction and delay in fracture by enhancement of pure shear deformation. However, the dented and undented specimens had the same ultimate tensile strength. These results provide us a new concept to increase total elongation of UFG materials.

High Strain Rate Superplasticity in a Zr and Sc Modified 7075 Aluminum Alloy Produced by ECAP

2008 ◽  
Vol 584-586 ◽  
pp. 164-169 ◽  
Author(s):  
Krystof Turba ◽  
Premysl Malek ◽  
Edgar F. Rauch ◽  
Miroslav Cieslar
Keyword(s):  
Aluminum Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Rate Sensitivity ◽  
7075 Aluminum Alloy ◽  
Fine Grained ◽  
Angular Pressing ◽  
Average Grain Size ◽  
Elongation To Failure

Equal-channel angular pressing (ECAP) at 443 K was used to introduce an ultra-fine grained (UFG) microstructure to a Zr and Sc modified 7075 aluminum alloy. Using the methods of TEM and EBSD, an average grain size of 0.6 1m was recorded after the pressing. The UFG microstructure remained very stable up to the temperature of 723 K, where the material exhibited high strain rate superplasticity (HSRSP) with elongations to failure of 610 % and 410 % at initial strain rates of 6.4 x 10-2 s-1 and 1 x 10-1 s-1, respectively. A strain rate sensitivity parameter m in the vicinity of 0.45 was observed at temperatures as high as 773 K. At this temperature, the material still reached an elongation to failure of 430 % at 2 x 10-2 s-1. These results confirm the stabilizing effect of the Zr and Sc additions on the UFG microstructure in a 7XXX series aluminum alloy produced by severe plastic deformation.

Superplastic Behavior and Microstructure of Titanium (Ti-6Al-4V) Friction Stir Welds Made under a Variety of Processing Conditions

2010 ◽  
Vol 433 ◽  
pp. 169-176 ◽  
Author(s):  
Paul Edwards ◽  
Mamidala Ramulu ◽  
Daniel G. Sanders
Keyword(s):  
Friction Stir Welding ◽  
Base Material ◽  
Superplastic Forming ◽  
Spindle Speed ◽  
Processing Conditions ◽  
Superplastic Behavior ◽  
Friction Stir ◽  
Fine Grained ◽  
Weld Parameters

Friction Stir Welding of Ti-6Al-4V was performed on 5 mm thickness plate in order to assess the affect of welding conditions on the resulting microstructure and superplastic forming behavior of the joints. A variety of welding conditions were tested and all welds were subsequently Superplastically formed. It was found that the weld parameters do influence the microstructure and degree of superplastic performance of the joints. Spindle speed was found to have the most dominant affect on the resulting microstructure and superplastic forming behavior. Low spindle speed welds lead to fine grained microstructures and highly superplastic welds, relative to the base material, while high spindle speed welds larger grained microstructures and less superplastic welds.

Fracture Behavior of an AlMgMnSc Alloy at Different Temperatures

2021 ◽  
Vol 1016 ◽  
pp. 292-296
Author(s):  
Yuliya Igorevna Borisova ◽  
Diana Yuzbekova ◽  
Anna Mogucheva
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Brittle Fracture ◽  
Fracture Surface ◽  
Strain Rate ◽  
Fracture Behavior ◽  
Fine Grained ◽  
Angular Pressing ◽  
Different Temperatures ◽  
Elongation To Failure

An Al-4.57Mg-0.35Mn-0.2Sc-0.09Zr (wt. %) alloy was studied in the fine-grained state obtaining after equal channel angular pressing. The mechanical behavior of alloy at the temperatures 173 K, 298 K and 348 K and at strain rate 1×10–3 s–1 is studied. Increase of the temperature testing from 173 K to 348 K decreases the yield stress by 80 MPa, the ultimate tensile strength by 60 MPa while elongation-to failure increases by a factor of 1.4. It was found that at temperatures of 298 and 173 K, the studied alloy mainly demonstrates the mode of ductile fracture, and at a temperature of 348 K the mechanism can be described as mixed ductile-brittle fracture. It was also established that of the studied alloy is the temperature dependence of the size of the dimples on the fracture surface. The formation of smaller dimples in the samples deformed at 298 K was observed.

scholarly journals Usage of Ti-surface-modified filler material to increase the joint strength of High-Strength Low Alloyed (HSLA) steels under different load types

2020 ◽  
Vol 2 (12) ◽  
Author(s):  
Kai Treutler ◽  
Volker Wesling
Keyword(s):  
Dynamic Load ◽  
Base Material ◽  
High Strength ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Structural Steels ◽  
Titanium Coating ◽  
Fine Grained ◽  
Weld Toe ◽  
Load Types

AbstractWelding-related loss of strength, especially in the case of fatigue, significantly reduces the range of applications for high-strength fine-grained structural steels. In order to counteract this situation, the aim of the work is to increase the strength of welded joints made of high-strength fine-grained structural steels by using coated welding consumables. This is described using the example of a titanium coating for quasi-static and abrupt dynamic load and fatigue. The thermomechanical rolled fine-grained structural steel S700MC is used as the base material, using a welding filler of the same type. MAG welding was used to produce the fillet welds on a T-joint. In addition to tensile tests at four different load speeds up to 2 m/s, the results of fatigue tests are presented. In addition, the microstructure of the weld seams is examined by metallographic methods and the scanning electron microscope. A comparison with two joints from an unmodified variant and another steel grade with comparable properties (S690QL) serves to classify the results. It is shown that the use of modified filler metals has a significant influence on the overall strength of the welded joint due to the rounding of the weld toe. Thus, the fatigue strength can be increased by around 50%. In addition, the strength under sudden dynamic load can be increased by 10%.

Low-Temperature Superplasticity in an Al–Mg–Mn Alloy Subjected to ECAP and Subsequent Isothermal Rolling

2012 ◽  
Vol 735 ◽  
pp. 347-352
Author(s):  
Ilya Nikulin ◽  
Alla Kipelova ◽  
Rustam Kaibyshev
Keyword(s):  
Low Temperature ◽  
Strain Rate ◽  
Rate Sensitivity ◽  
Initial Strain Rate ◽  
Sensitivity Coefficient ◽  
Angular Pressing ◽  
Elongation To Failure ◽  
Fine Grained Structure ◽  
Superplastic Properties ◽  
Average Size

An ultra-fine grained structure with an average size of ~ 1 μm was produced in a commercial Al–5.4%Mg–0.5%Mn–0.1%Zr–0.12%Si–0.014%Fe alloy by hot equal-channel angular pressing (ECAP) followed by isothermal rolling (IR). It was found that in the strain rate interval from 5.6×10-4to 2.8×10-2s-1the alloy exhibits a low-temperature superplasticity with elongation-to-failure exceeding 400% and the strain rate sensitivity coefficient of ~0.3. The highest elongation-to-failure of ~ 620% appeared at a temperature of ~ 275°C and an initial strain rate of ~ 5.6×10-3s-1. The relationship between superplastic properties and microstructural evolution of the examined alloy is discussed.

PERSPECTIVE WELDING TECHNOLOGIES OF ALUMINUM-LITHIUM ALLOY V-1469 APPLIED TO FUSELAGE PANELS

2020 ◽  
pp. 35-46
Author(s):  
M.D. Panteleev ◽  
◽  
A.V. Sviridov ◽  
A.A. Skupov ◽  
N.S. Odintsov ◽  
...  
Keyword(s):  
Friction Stir Welding ◽  
Laser Welding ◽  
Low Cycle Fatigue ◽  
Base Material ◽  
High Strength ◽  
Friction Stir ◽  
Lithium Alloy ◽  
Aluminum Lithium Alloy ◽  
Aluminum Lithium ◽  
Welding Processes

In this work, we investigated the technological features of promising technologies for laser welding and friction stir welding of high-strength aluminum-lithium alloy V-1469. The modes of laser welding and friction stir welding have been carried out. In this article, we showed the perspective welding methods provide high values of ductility and impact toughness, while the strength of welded joints is not less than 0,8 of the strength of the base material and values of low cycle fatigue is not less than 110•103 cycles. The results allows to propose laser welding and friction stir welding processes as an alternative to riveted joint for aluminum-lithium alloy V-1469 as applied to the elements of the fuselage.

Hybrid Design Concept Using High-Strength Cast Steel Inserts for Tubular Joints of Offshore Structures

1998 ◽  
Vol 120 (1) ◽  
pp. 10-19 ◽  
Author(s):  
C. M. Sonsino ◽  
R. Umbach
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Large Scale ◽  
Fatigue Behavior ◽  
Cast Steel ◽  
High Strength ◽  
Offshore Structures ◽  
Fine Grained ◽  
Tubular Joints ◽  
Medium Strength

In a joint project of a German working group supported by the ECSC and the Studiengesellschaft fu¨r Stahlanwendung e.V., the fatigue behavior of large-scale hybrid tubular joints with inserts manufactured from the high-strength cast steel GS-12 MnMo 7 4 welded into tubular members formed from the fine-grained steel StE 500 were compared to the behavior of large-scale welded tubular joints. The latter were made from medium-strength fine-grained steel StE 355 and high-strength StE 690. In addition, data from hybrid joints with cast steel inserts of medium-strength GS-8 Mn 7 welded into StE 355 tubulars is available for comparison. The tests were carried out under variable amplitude loading in artificial seawater. The results were evaluated for the failure criteria fatigue life to crack initiation (a = 1 mm) and through crack. With medium-strength (Rp0.2 > 355 N/mm2) hybrid tubulars, where by the use of cast steel inserts the welds were removed into areas of lower stress concentration, fatigue lives higher than a factor of 100 were achieved compared to the welded nodes, even those made from StE 690. However, by the use of high-strength (Rp0.2 > 500 N/mm2) cast steel inserts and tubular members of corresponding strength, the fatigue life to crack initiation was improved by a factor of two despite a thickness reduction compared to the medium-strength design. Post-weld treatments of the welded tubulars without cast steel inserts like shot-peening, TIG-dressing, or their combination resulted only in a slight increase of fatigue life. The results of this investigation do not only show how to improve the fatigue life by a new design using cast steel inserts, but indicate also how to revise design codes from the point of damage calculation (damage sum of 0.50 for welded nodes and 0.25 for cast steel inserts instead of the conventional value of 1.00), as well as consideration of fatigue life to initiation of a technically detectable crack with a defined depth e.g., a = 1 mm.

Influence of Severe Plastic Deformation on Mechanical Properties of an AA5024 Alloy

2016 ◽  
Vol 879 ◽  
pp. 1317-1322 ◽  
Author(s):  
Anna Mogucheva ◽  
Diana Yuzbekova ◽  
Tatiana Lebedkina ◽  
Mikhail Lebyodkin ◽  
Rustam Kaibyshev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strength ◽  
Coarse Grained ◽  
Type B ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Dislocation Strengthening

The paper reports on the effect of severe plastic deformation on mechanical properties of an Al-4.57Mg-0.35Mn-0.2Sc-0.09Zr (in wt. pct.) alloy processed by equal channel angular pressing followed by cold rolling (CR). The sheets of the 5024 alloy with coarse grained (CG) structure exhibited a yield stress (YS) near 410 MPa and an ultimate tensile strength (UTS) of 480 MPa, while the YS and UTS of this material with ultrafine-grained (UFG) structure increased to 530 and 560 MPa, respectively. On the other hand, the elongation to failure decreased by a factor of 2 and 4 after CR and CR following ECAP, respectively. It was shown that dislocation strengthening attributed to extensive CR plays a major role in achieving high strength of this alloy. Besides these macroscopic characteristics, jerky flow caused by the Portevin-Le Chatelier (PLC) instability of plastic deformation was examined. The formation of UFG structure results in a transition from mixed type A+B to pure type B PLC serrations. No such effect on the serrations type was observed after CR.

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