scholarly journals Evaluation of Cryogenic Mechanical Properties of Resistance Seam-Welded Invar Alloy Sheet by Instrumented Indentation Test

2020 ◽  
Vol 8 (12) ◽  
pp. 1009
Author(s):  
Seunghun Choi ◽  
Jongho Won ◽  
Jung-Jun Lee ◽  
Hee-Keun Lee ◽  
Seong-Min Kim ◽  
...  
Keyword(s):  
Grain Size ◽  
Plastic Zone ◽  
Base Material ◽  
Indentation Test ◽  
Welding Current ◽  
Optical Microscope ◽  
Alloy Sheet ◽  
Invar Alloy ◽  
Instrumented Indentation ◽  
Average Grain Size

Invar alloy sheet was welded by resistance seam welding (RSW) with a constant electrode force and three different welding currents. Tensile properties were evaluated using instrumented indentation testing (IIT) with a spherical indenter and microstructure observations were obtained under an optical microscope. IIT performed on the base material at room temperature (RT) and −163 °C, a cryogenic temperature (CT), gave results in good agreement with those of tensile testing. The strength of each zone was higher in the order of heat-affected zone (HAZ) < weld nugget (WN) < base material (BM) because the amount of cold working was least in the BM, heavy metal elements and carbon vaporized during melting, and the WN was formed more tightly than the HAZ, effectively constraining the plastic zone generated by the indentation. As for the welding current, the nugget, which becomes larger and tighter as the current increases, more effectively constrained the plastic zone in the indentation, and this soon increased the strength. Generally, Invar is known to consist of single-phase austenite, and microstructure observations have confirmed that the average grain size is ordered as BM < HAZ < WN. Fan-like columnar grains developed in the direction of the temperature gradient, and equiaxed grains were observed near the BM. It was confirmed that the grain size in the WN also increases as the current is increased. Interestingly, the constraint effect with increasing nugget size was more important for strength than the grain size.

Microstructure and Texture Evolution during Friction Stir Processing of AZ31 Mg Alloy

2010 ◽  
Vol 654-656 ◽  
pp. 1195-1200 ◽  
Author(s):  
Ren Long Xin ◽  
Bo Li ◽  
Qing Liu
Keyword(s):  
Grain Size ◽  
Texture Evolution ◽  
Base Material ◽  
Alloy Sheet ◽  
Electron Back Scatter Diffraction ◽  
Mg Alloy ◽  
Gradual Change ◽  
Friction Stir ◽  
Az31 Mg Alloy ◽  
Average Grain Size

In this study, a well-textured AZ31 Mg alloy sheet was friction stir (FS) processed, and the microstructure and texture evolution in various regions of the processed alloy were examined by optical microscopy (OM) and electron back scatter diffraction (EBSD). The results showed that the grain size in the FS zone was significantly refined compared to that in the base material (BM). The average grain size in the thermomechanically affected zone (TMAZ) and heat-affected zone (HAZ) was comparable with that in the BM. There is a gradual change of local texture from BM to FS zone due to plastic flow together with heating input during the FS processing. The <0002> direction was roughly parallel to the cylindrical pin surface normal of the FS zone. The <0002> direction in the HAZ is similar to that in the BM, but more diffuse. The <0002> direction in the TMAZ was tilted 25~30o away from the ND and there is a distinct boundary between the FS zone and TMAZ at the advancing side which introduced an incompatibility between the FS zone and TMAZ. This might explain the fact that the transverse FS processed Mg alloys commonly fracture at the advancing side during tensile tests.

Microstructural Characterization and Tensile Behavior of TA1 Titanium Alloy Sheet Welded by Electron Beam Welding

2021 ◽  
Vol 1027 ◽  
pp. 149-154
Author(s):  
Sen Dong Gu ◽  
Ji Peng Zhao ◽  
Rui Jie Ouyang ◽  
Yong Hong Zhang
Keyword(s):  
Titanium Alloy ◽  
Electron Beam ◽  
Fusion Zone ◽  
Heat Affected Zone ◽  
Electron Beam Welding ◽  
Base Material ◽  
Optical Microscope ◽  
Alloy Sheet ◽  
Tensile Behavior ◽  
Electron Backscattered Diffraction

In the present study, TA1 titanium alloy sheets with a thickness of 0.8mm were welded by electron beam welding. Microstructure of the welded region was investigated using optical microscope and electron backscattered diffraction. Then, the tensile test was conducted to analyse the tensile behavior of the welded sheets as well as the fractography of the fracture surfaces. It is shown that the mean grain size in the heat-affected zone is smaller than that in the fusion zone and base material. The strength of the base metal is lower than that of the fusion zone and heat-affected zone. The average values of the yield strength, tensile strength and elongation of the tensile specimens are 224MPa, 335MPa and 35%, respectively. In addition, the tensile specimens of the welded sheets suffer both ductile and brittle deformation during the tensile tests.

Grain Structure and Surface Roughness of Four Commercial NiTi Orthodontic Archwires

2017 ◽  
Vol 266 ◽  
pp. 257-263
Author(s):  
Wassana Wichai ◽  
Rutchadakorn Isarapatanapong ◽  
Niwat Anuwongnukroh ◽  
Surachai Dechkunakorn
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Optical Microscope ◽  
Grain Structure ◽  
Wire Surface ◽  
Average Grain Size ◽  
Electron Mode ◽  
The Mean ◽  
The Wire ◽  
Orthodontic Archwires

This study investigated four commercially available NiTi orthodontic archwires from different manufactures for their grain structure and surface roughness.Four commercially available pre-formed NiTi orthodontic archwire (Ormco, Sentalloy, Highland and NIC) with diameter 0.016 x 0.022 inch2 were tested. The wire samples were polished and etched to evaluate the morphology and structure of wire surface. Each NiTi archwire was investigated under a reflected light microscope of an Optical Microscope to analyze its grain structure and size, in longitudinal surfaces. The surfaces of wire were qualitatively examined in the secondary electron mode at common magnification (500X). The surface roughness was also evaluated by a surface roughness tester. The descriptive statistic was evaluated the mean and standard deviation of surface roughness and Medcale T-Test was to test the mean difference of the surface roughness in each brands. This study showed an average grain size of 2-8 μm for each NiTi archwire. The wire surface of Ormco and Highland showed straiations along the longitudinal axes, however Sentalloy and NIC showed small pores on the wire surface. The surface roughness was 0.09 μm for Highland, 0.25 μm for Sentalloy, 0.28 μm for Ormco and 0.46 μm for NIC archwire. The Highland was smoothest and NIC was the roughest. There were in significant (p < 0.05) difference of surface roughness of each brands. The results showed that the four manufactures NiTi archwires were different in grain size, wire surface and surface roughness. During clinical application, these archwires may exhibit different mechanical properties, such as strength, hardness, ductity, and friction because of their microstructure.

Investigating the Relationships Between Structures and Properties of Al Alloys Incorporated With Ti and Mg Inclusions

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Halil Ibrahim Kurt ◽  
Ibrahim H. Guzelbey ◽  
Serdar Salman ◽  
Razamzan Asmatulu ◽  
Mustafa Dere
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Elevated Temperatures ◽  
Solidification Process ◽  
Optical Microscope ◽  
Industrial Applications ◽  
Al Alloys ◽  
Average Grain Size ◽  
Solidification Processes ◽  
Grain Size And Shape

This study investigates the influence of titanium (Ti) and magnesium (Mg) additions on aluminum (Al) alloys in order to evaluate the relationship between the structure and properties of the new alloys. The alloys obtained at elevated temperatures mainly consist of Al–2Mg–1Ti, Al–2Mg–3Ti, Al–4Mg–2Ti, and Al–6Mg–2Ti alloys, as well as α and τ solid solution phases of intermetallic structures. Microstructural analyses were performed using X-ray diffraction (XRD), optical microscope, and energy dispersive spectrometry (EDS) techniques. Test results show that the average grain size of the alloys decreased with the addition of Ti inclusions during the casting and solidification processes, and the smallest grain size was found to be 90 μm for the Al–6Mg–3Ti alloy. In addition, tensile properties of the Al–Mg–Ti alloys were initially improved and then worsened after the addition of higher concentrations of Ti. The highest tensile and hardness values of the alloys were Al–4Mg–2Ti (205 MPa) and Al–6Mg–3Ti (80 BHN). The primary reasons for having higher mechanical properties may be attributed to strengthening of the solid solution and refinement of the grain size and shape during the solidification process. For this study, the optimum concentrations of Ti and Mg added to the Al alloys were 4 and 2 wt.%, respectively. This study may be useful for field researchers to develop new classes of Al alloys for various industrial applications.

Annealing Treatment for Superplastic Forming of Twin Roll Casted AZ31 Magnesium Sheet

2011 ◽  
Vol 239-242 ◽  
pp. 50-54 ◽  
Author(s):  
Guo Dong Shi ◽  
Jun Qiao
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Mechanical Test ◽  
Dynamic Balance ◽  
Annealing Treatment ◽  
Optical Microscope ◽  
Grain Structure ◽  
Average Grain Size ◽  
Az31 Sheet ◽  
Twin Roll

Annealing treatments at 200°C, 250 °C, 300°C, and 350°C were conducted on a twin-roll casted AZ31 sheet with an initial average grain size of 10.11 mm. Microstructure and mechanical behaviors were studied by optical microscope observation and tensile mechanical test. Expermeintal results show that grain size experienced three stage evolution during 180 min annealing at each temperature: recrystallization refinement, stabilization under dynamic balance of recrystallization and grain growth, and grain growth. The minimum average grain size of 5.96 μm was achieved after 120 min annealing at 200°C. The refined grain structure causes a decrease of ultimate tensile strength and an increase of elongation, and facilitates superplastic deformation of the material.

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.

Structural, Morphological and Composition Analysis of Nanocrystalline La0.67Ba0.33MnO3 Powder

2012 ◽  
Vol 584 ◽  
pp. 239-242
Author(s):  
C. Seshendra Reddy ◽  
A. Sivasankar Reddy ◽  
P. Sreedhara Reddy
Keyword(s):  
Grain Size ◽  
Sintering Temperature ◽  
Base Material ◽  
Solid State Reaction Method ◽  
Rhombohedral Structure ◽  
Composition Analysis ◽  
Scanning Electron Micrographs ◽  
Atomic Force ◽  
Average Grain Size ◽  
Composition Properties

La0.67Ba0.33MnO3 powders were successfully prepared by a standard solid state reaction method, and systematically investigated the influence of the sintering temperature on the structural, microstructure, composition properties. The XRD pattern showed that the as prepared LBMO material was in single-phase with rhombohedral structure. From the scanning electron micrographs, it was observed that the grain size increased with sintering temperature and the average grain size was ~40nm.The surface roughness was measured by atomic force microscope and the RMS roughness of samples was in the range 48 to 85 nm. The as prepared samples exhibited nearly the same composition of the base material.

Investigation of Microstructure and Mechanical Properties of Friction Stir Lap Jointed Ni Base Superalloy

2012 ◽  
Vol 724 ◽  
pp. 481-485
Author(s):  
Kuk Hyun Song ◽  
Kazuhiro Nakata
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Friction Stir Welding ◽  
Base Material ◽  
Lap Joints ◽  
Stir Zone ◽  
Inconel 600 ◽  
Friction Stir ◽  
Microstructure And Mechanical Properties ◽  
Average Grain Size

This study evaluated the microstructure and mechanical properties of friction stir welded lap joints. Inconel 600 and SS 400 as experimental materials were selected, and friction stir welding was carried out at tool rotation speed of 200 rpm and welding speed of 100 mm/min. Applying the friction stir welding was notably effective to reduce the grain size of the stir zone, as a result, the average grain size of Inconel 600 was reduced from 20 μm in the base material to 8.5 μm in the stir zone. Joint interface between Inconel 600 and SS 400 showed a sound weld without voids and cracks. Also, the hook, along the Inconel 600 alloy from SS 400, was formed at advancing side, which directly affected an increase in peel strength. In this study, we systematically discussed the evolution on microstructure and mechanical properties of friction stir lap jointed Inconel 600 and SS 400.

Effect of Solution Treatment Temperature on the Microstructure of Fe-33Ni-19Cr Alloy

2020 ◽  
Vol 1010 ◽  
pp. 21-27
Author(s):  
Noraziana Parimin ◽  
Esah Hamzah
Keyword(s):  
Grain Size ◽  
Solution Treatment ◽  
Optical Microscope ◽  
Treatment Temperature ◽  
Solution Treatment Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solution Treated ◽  
Average Grain Size ◽  
Different Temperatures

The effect of solution treatment temperature on the microstructure, phase present and hardness on Fe-33Ni-19Cr alloy was study in this work. The Fe-33Ni-19Cr alloy was experienced a solution treatment process at six different temperatures which are 950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C and 1200 °C for 3 hours soaking time followed by water quench. The average grain size was measured by using linear intercept methods ASTM E112. Microstructure of solution-treated Fe-33Ni-19Cr alloy was characterized by using optical microscope and scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX) spectrometer. The phase present was analyzed using x-ray diffraction (XRD) technique. The Vickers hardness was used to measure the hardness of solution-treated Fe-33Ni-19Cr alloy. Increasing the solution treatment temperatures were increase the average grain size of solution-treated Fe-33Ni-19Cr alloy. In addition, all samples exhibited an equiaxed matrix grain with slight distribution of precipitates particles. The hardness of solution-treated Fe-33Ni-19Cr alloy was decrease as the solution treatment temperature increase.

Microstructure and Mechanical Properties of GTAW Welded Joint of Invar Alloy

2021 ◽  
pp. 1-8
Author(s):  
DongSheng Zhao ◽  
TianFei Zhang ◽  
LiangLiang Wu ◽  
LeLe Kong ◽  
YuJun Liu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Welded Joint ◽  
Welding Current ◽  
Liquid Films ◽  
Invar Alloy ◽  
Welding Parameters ◽  
Welding Seam ◽  
Microstructure And Mechanical Properties

Experiment of automatic gas tungsten arc welding of liquefied natural gas carrier Invar alloy with a thickness of .7 mm was completed, and the welding parameters were optimized, as well as microstructure and mechanical properties of the welded joint were measured and analyzed. The grain size of the area near the weld centerline was small, mainly cellular dendrites, and the grain size on both sides of the weld centerline increased gradually, mainly dendrites, whereas the grain size near fusion line was larger, and there were more columnar crystals. The heat-affected zone was composed of coarse austenite grains. Transgranular cracks were the main cracks in the welding seam. When welding current was 40 A, frequency was 120 Hz, and welding speed was 350 mm/min, tensile strength of the welded joint was 446.9 MPa, which 88.1% of the base metal’s tensile strength and 10.3% of the fracture elongation. The fracture surface of tensile specimens showed typical plastic fracture characteristics, with no obvious crack characteristics, and no eutectic liquid films were observed.

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