Microstructural and Mechanical Characterization of Autogenous GTAW Weld in High-Manganese Austenitic Steel Ti-Containing with Thermal Analysis

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3963-3969
Author(s):  
V. García-García ◽  
I. Mejía ◽  
F. Reyes-Calderón
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Weld Joint ◽  
Heat Input ◽  
Thermal Field ◽  
Twip Steel ◽  
Experimental Results ◽  
Butt Weld ◽  
Average Grain Size ◽  
Gtaw Process

ABSTRACTThe welding heat input has been pointed out as a main limiting factor for TWinnig Induced Plasticity (TWIP) steel weldability. Scarce research works have been focused on the study of application and effects of the Gas Tungsten Arc Welding (GTAW) process in the TWIP steel, especially in higher thickness plate. In this research work was conducted a detailed analysis of a butt weld joint performed in plates of TWIP steel microalloyed with titanium (TWIP-Ti) of 6.3 mm thickness. The autogenous GTAW process with low heat input was applied. The analysis considered grain size measurements, second phases identification, post-weld mechanical properties (microhardness) and the welding thermal field. A Finite Element Model (FEM), validated through experimental results, allowed correlating metallurgical results with the thermal field. Likewise, the phases prediction carried out by means of JMatPro 9.0 software during solidification process as well as the estimation of particle precipitation were in good agreement with the experimental results. These predictive diagrams were calculated taking into account the TWIP-Ti steel chemical composition, the grain size measured in critical weld regions and experimental cooling rates. The low heat input improved the microstructural conditions in the heat affected zone (HAZ) whose average grain size and precipitate particles, like (C, N)Ti, promoted good mechanical properties as compared to the base material (as-solution condition). Some particles like Al2O3 y MnS produced microporosities in the HAZ. Despite this, the weld joint did not present hot cracking in the FZ-HAZ interface.

Heat Input Effect on the Microstructure of Twinning-Induced Plasticity (TWIP) Steel Welded Joints Through the GTAW Process

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3949-3956
Author(s):  
H. Hernández-Belmontes ◽  
I. Mejía ◽  
V. García-García ◽  
C. Maldonado
Keyword(s):  
Phase Transformations ◽  
Heat Input ◽  
Twip Steel ◽  
Research Work ◽  
Second Phase ◽  
Current Electrode ◽  
Weld Joints ◽  
Average Grain Size ◽  
Gtaw Process ◽  
Twip Steels

ABSTRACTHigh-Mn Twinning Induced Plasticity (TWIP) steels are an excellent alternative in the design of structural components for the automotive industry. The TWIP steels application allows weight reduction, maintaining the performance of vehicles. Nowadays the research works focused on TWIP steel weldability are relative scarce. It is well-known that weldability is one of the main limitations for industrial application of TWIP steel. The main goal of this research work was studied the effect of heat input on the microstructural changes generated in a TWIP steel microalloyed with Ti. A pair of welds were performed through Gas Tungsten Arc Welding (GTAW) process. The GTAW process was carried out without filler material, using Direc Current Electrode Negative (DCEN), tungsten electrode EWTh-2 and Ar as shielding gas. The microstructure and average grain size in the fusion (FZ) and heat affected zone (HAZ) were determined by light optical metallography (LOM). Elements segregation in the FZ was evaluated using point and elemental mapping chemical analysis (EPMA) by Scanning Electron Microscopy and Electron Dispersive Spectroscopy (SEM-EDS). Phase transformations were evaluated using X-ray diffraction (XRD). Finally, the hardness were measured by means of Vickers microhardness testing (HV500). The results show that the FZ is characterized by a dendritic solidification pattern. Meanwhile, the HAZ presented equiaxed grains in both weld joints. On the other hand, the TWIP-Ti steel weldments did not present austenite phase transformations. Nevertheless, the FZ exhibited variations in the chemical elements distribution (Mn, Al, Si and C), which were higher as the heat input increases. Finally, the heat input reduced the microhardness of TWIP-Ti steel weld joints. Although post-welding hardness recovery was detected, which is associated with precipitation of Ti second-phase particles.

Influence of Grain Size on Mechanical Properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP Steel

2011 ◽  
Vol 197-198 ◽  
pp. 655-661
Author(s):  
Ze Bin Yang ◽  
Ding Yi Zhu ◽  
Wei Fa Yi ◽  
Shu Mei Lin ◽  
Cheng Mei Du
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Strain Hardening ◽  
Twip Steel ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Microstructure Observation ◽  
Transmission Electron ◽  
Average Grain Size

We investigate the influence of grain size on mechanical properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP steel by unidirectional tensile. Meanwhile the microstructures of the TWIP steel were observed and analyzed by optical microscope (OM) and transmission electron microscope (TEM). The experimental results show that the TWIP steel’s yield strength and tensile strength decrease with the increasing of grain size, whereas the plasticity increases with it. When the average grain size reaches to 27μm, the tensile strength is 1080MPa, the elongation percentage is 77%, and the strength-plasticity product achieves the 83160MPa•%. Steel’s strain hardening rate can be changed from three-stage to four-stage with the increasing of grain sizes, the areas of strain hardening by twin deformation mechanism are expanded. Through the microstructure observation we found that, coarse-grained TWIP steel conducts to twinning formation, the high density twins can increase the alloy’s ductility by splitting the grain.

Effects of Annealing Temperature on the Microstructure and Mechanical Properties of Electrodeposited Ni-Fe Alloy Foils

2017 ◽  
Vol 36 (3) ◽  
pp. 223-232 ◽  
Author(s):  
H. R. Ren ◽  
L. Guo ◽  
Z. C. Guo
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Grain Size ◽  
Elastic Modulus ◽  
Annealing Temperature ◽  
Experimental Results ◽  
Structure Defects ◽  
Alloy Foil ◽  
Heat Treated ◽  
Average Grain Size

AbstractThe plasticity, elastic modulus and thermal stability restrict the applications of electrodeposited nanocrystalline Ni-Fe alloy foils. To improve its mechanical properties, the electrodeposited Ni-Fe alloy foils were heat treated within the temperature 900–1,150 °C. The microstructure and texture of the samples were further analyzed with a combination of SEM, XRD and EBSD. The experimental results indicated that the electrodeposited Ni-Fe alloy foil had poor mechanical properties at about 1,000 °C, which was mainly attributed to the development of a mixed grain microstructure. At 900–950 °C, the plastic and elastic modulus were greatly improved, which were owed to the uniformed microstructure and the decrease of structure defects. At 1,050–1,150 °C, the degree of the mixed grain microstructure decreased, resulting in improved plasticity and higher elastic modulus. However, the strength of the foil obviously decreased, which was mainly associated with the increase of the average grain size.

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

scholarly journals Development of Al–Mg–Si alloy performance by addition of grain refiner Al–5Ti–1B alloy

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110294
Author(s):  
Khaled Abd El-Aziz ◽  
Emad M Ahmed ◽  
Abdulaziz H Alghtani ◽  
Bassem F Felemban ◽  
Hafiz T Ali ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Corrosion Resistance ◽  
Testing Machine ◽  
Dendritic Structure ◽  
Grain Refiner ◽  
Corrosion Properties ◽  
Average Grain Size ◽  
Structural Applications ◽  
Alloy Addition

Aluminum alloys are the most essential part of all shaped castings manufactured, mainly in the automotive, food industry, and structural applications. There is little consensus as to the precise relationship between grain size after grain refinement and corrosion resistance; conflicting conclusions have been published showing that reduced grain size can decrease or increase corrosion resistance. The effect of Al–5Ti–1B grain refiner (GR alloy) with different percentages on the mechanical properties and corrosion behavior of Aluminum-magnesium-silicon alloy (Al–Mg–Si) was studied. The average grain size is determined according to the E112ASTM standard. The compressive test specimens were made as per ASTM: E8/E8M-16 standard to get their compressive properties. The bulk hardness using Vickers hardness testing machine at a load of 50 g. Electrochemical corrosion tests were carried out in 3.5 % NaCl solution using Autolab Potentiostat/Galvanostat (PGSTAT 30).The grain size of the Al–Mg–Si alloy was reduced from 82 to 46 µm by the addition of GR alloy. The morphology of α-Al dendrites changes from coarse dendritic structure to fine equiaxed grains due to the addition of GR alloy and segregation of Ti, which controls the growth of primary α-Al. In addition, the mechanical properties of the Al–Mg–Si alloy were improved by GR alloy addition. GR alloy addition to Al–Mg–Si alloy produced fine-grained structure and better hardness and compressive strength. The addition of GR alloy did not reveal any marked improvements in the corrosion properties of Al–Mg–Si alloy.

Vibratory weld conditioning during gas tungsten arc welding of al 5052 alloy on the mechanical and micro-structural behavior

2020 ◽  
Vol 17 (6) ◽  
pp. 831-836
Author(s):  
M. Vykunta Rao ◽  
Srinivasa Rao P. ◽  
B. Surendra Babu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Welded Joints ◽  
Great Influence ◽  
Welding Process ◽  
Microstructural Characterization ◽  
Content Type ◽  
Average Grain Size

Purpose Vibratory weld conditioning parameters have a great influence on the improvement of mechanical properties of weld connections. The purpose of this paper is to understand the influence of vibratory weld conditioning on the mechanical and microstructural characterization of aluminum 5052 alloy weldments. An attempt is made to understand the effect of the vibratory tungsten inert gas (TIG) welding process parameters on the hardness, ultimate tensile strength and microstructure of Al 5052-H32 alloy weldments. Design/methodology/approach Aluminum 5052 H32 specimens are welded at different combinations of vibromotor voltage inputs and time of vibrations. Voltage input is varied from 50 to 230 V at an interval of 10 V. At each voltage input to the vibromotor, there are three levels of time of vibration, i.e. 80, 90 and 100 s. The vibratory TIG-welded specimens are tested for their mechanical and microstructural properties. Findings The results indicate that the mechanical properties of aluminum alloy weld connections improved by increasing voltage input up to 160 V. Also, it has been observed that by increasing vibromotor voltage input beyond 160 V, mechanical properties were reduced significantly. It is also found that vibration time has less influence on the mechanical properties of weld connections. Improvement in hardness and ultimate tensile strength of vibratory welded joints is 16 and 14%, respectively, when compared without vibration, i.e. normal weld conditions. Average grain size is measured as per ASTM E 112–96. Average grain size is in the case of 0, 120, 160 and 230 is 20.709, 17.99, 16.57 and 20.8086 µm, respectively. Originality/value Novel vibratory TIG welded joints are prepared. Mechanical and micro-structural properties are tested.

Microstructures and Mechanical Properties of AZ61 Mg Alloy Processed by Equal Channel Angular Pressing

2012 ◽  
Vol 468-471 ◽  
pp. 2124-2127 ◽  
Author(s):  
Shao Feng Zeng ◽  
Kai Huai Yang ◽  
Wen Zhe Chen
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Uniform Elongation ◽  
Considerable Decrease ◽  
Angular Pressing ◽  
Az61 Magnesium Alloy ◽  
Average Grain Size ◽  
Microstructures And Mechanical Properties ◽  
Bimodal Grain Size

Equal channel angular pressing (ECAP) was applied to a commercial AZ61 magnesium alloy for up to 8 passes at temperatures as low as 473K. Microstructures and mechanical properties of as-received and ECAP deformed samples were investigated. The microstructure was initially not uniform with a “bimodal” grain size distribution but became increasingly homogeneous with further ECAP passes and the average grain size was considerably reduced from over 26 μm to below 5 μm. The ultimate tensile strength (UTS) decreases clearly after one pass, but increases significantly up to two passes, and then continuously slowly decreases up to six passes, and again increases slightly up to eight passes. In contrast, the uniform elongation increased significantly up to 3 passes, followed by considerable decrease up to 8 passes. These observations may be attributed to combined effects of grain refinement and texture development.

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

Effect of Li on Mechanical Properties and Electrical Conductivity of the Al–Zn–Cu–Mg Based Alloys

2021 ◽  
Vol 21 (9) ◽  
pp. 4897-4901
Author(s):  
Hyo-Sang Yoo ◽  
Yong-Ho Kim ◽  
Hyeon-Taek Son
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Tensile Strength ◽  
Spherical Particles ◽  
Al Alloy ◽  
High Angle ◽  
Average Grain Size ◽  
Strength Improvement ◽  
Li Content

In this study, changes in the microstructure, mechanical properties, and electrical conductivity of cast and extruded Al–Zn–Cu–Mg based alloys with the addition of Li (0, 0.5 and 1.0 wt.%) were investigated. The Al–Zn–Cu–Mg–xLi alloys were cast and homogenized at 570 °C for 4 hours. The billets were hot extruded into rod that were 12 mm in diameter with a reduction ratio of 38:1 at 550 °C. As the amount of Li added increased from 0 to 1.0 wt.%, the average grain size of the extruded Al alloy increased from 259.2 to 383.0 µm, and the high-angle grain boundaries (HGBs) fraction decreased from 64.0 to 52.1%. As the Li content increased from 0 to 1.0 wt.%, the elongation was not significantly different from 27.8 to 27.4% and the ultimate tensile strength (UTS) was improved from 146.7 to 160.6 MPa. As Li was added, spherical particles bonded to each other, forming an irregular particles. It is thought that these irregular particles contribute to the strength improvement.

Nondestructive Evaluation Method of Average Grain Size in TWIP Steel by Laser Ultrasonic

2018 ◽  
Vol 913 ◽  
pp. 324-330
Author(s):  
Yan Jie Zhang ◽  
Xiao Chen Wang ◽  
Quan Yang ◽  
Ren Jie Xue ◽  
An Min Yin
Keyword(s):  
Grain Size ◽  
Manufacturing Industry ◽  
Evaluation Method ◽  
High Efficiency ◽  
Standard Sample ◽  
Twip Steel ◽  
Test Sample ◽  
Standard Samples ◽  
Laser Ultrasonic ◽  
Average Grain Size

TWIP steel has the characteristics of high elongation and high tensile strength at room temperature, and therefore it is widely used in the automobile manufacturing industry. Since the grain size has a very important influence on its mechanical properties and corrosion resistance it is significant to study the average grain size of TWIP steel. In this experiment, the specimens were heated to 700~1000°C and preserved for one hour, and the recrystallized structures with different average grain sizes were obtained. All the samples were tested by laser ultrasonic experimental platform and the standard sample was selected. Then the attenuation coefficients of remaining samples were compared with the standard samples by conventional methods. The results showed that the larger the difference between the average grain size of the test sample and the standard sample is, the greater the error of the test will be. The new evaluation model was established by the improved method, and the prediction error was reduced to 5.44~11.61%, which proved the effectiveness of the new method. In addition, laser ultrasonic testing has the advantages of high efficiency and no damage compared with traditional methods.

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