Metallographic, Structural and Mechanical Characterization of Weld Nuggets in Fe‐Mn‐Al‐C Low‐Density Steels Microalloyed with Ti/B and Ce/La by GTAW Process

2021 ◽  
Author(s):  
Carlos Enrique Coronado-Alba ◽  
Ignacio Mejía ◽  
José María Cabrera
Keyword(s):  
Mechanical Characterization ◽  
Low Density ◽  
Gtaw Process

Microstructural and Mechanical Characterization of Nitinol GTAW and FB Welds of Titanium

2006 ◽  
Vol 509 ◽  
pp. 165-170 ◽  
Author(s):  
Alla Kabatskaia Ivanovna ◽  
Victor M. López-Hirata ◽  
Eduardo Oliva López ◽  
Ricardo Rodríguez Figueroa ◽  
Jorge Rodríguez Miramontes
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Mechanical Characterization ◽  
Dendritic Structure ◽  
Intermetallic Phases ◽  
Atomic Diffusion ◽  
Rich Phase ◽  
Gas Tungsten Arc ◽  
Gtaw Process

Microstructural and mechanical characterization of Nitinol gas tungsten arc weld (GTAW) and furnace brazing (FB) welds for grade 1 titanium plates are carried out in order to study the microstructure developed after welding and its effect on the mechanical properties of welds. The GTAW process yields the highest hardness weld. The constituents for this weld consist of a dendritic structure of NiTi and NiTi2 intermetallic phases. The FB process promotes a change of the welds chemical composition due to atomic diffusion of Ti. The weld microconstituents consist of a mixture of a Ti-rich and NiTi2 eutectic and a proeutectic Ti-rich phase.

Metallographic, Structural and Mechanical Characterization of a Low Density Fe-Mn-Al-C Steel Microalloyed with Ti/B in As-Cast and Homogenized Conditions

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3971-3978 ◽  
Author(s):  
O.E. Villanueva-Perez ◽  
I. Mejía ◽  
V. García-García ◽  
A. Bedolla-Jacuinde
Keyword(s):  
Grain Size ◽  
Mechanical Characterization ◽  
The Other ◽  
Low Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Other Hand ◽  
Average Grain Size ◽  
Cast Condition

ABSTRACTLow density (LD) steels have shown particular characteristics in terms of mechanical properties and microstructure, since they have high strength, high ductility and density reduction up to 18%. On the other hand, the addition of microalloying elements such as Ti and B generate hardening by solid solution and precipitation, as well as grain refinement effect. LD steels generate nano-sized kappa phase precipitated from the austenite matrix, and these advanced steels can reach strength and elongation up to 780 MPa and 60%, respectively. The main objective of this research work is the metallographic, structural and mechanical characterization of a LD steel microalloyed with Ti/B in as-cast and -homogenized conditions. For this purpose a Fe-27Mn-7Al-1.2C (%wt) LD steel microalloyed with Ti/B was melted in a vacuum-induction furnace and cast in metallic mold. LD-Ti/B steel samples were homogenized at 1100 °C during 20, 50, 100, 150 and 200 minutes followed by water quenching. Metallographic, structural and mechanical characterization was carried out by optical (LOM) and scanning electron (SEM) microscopy, X-ray diffraction (XRD) and microhardness Vickers testing (HV10), respectively. In general, results showed a typical dendritic microstructure with average grain size of 1256 μm in the as-cast condition. On the other hand, the as-homogenized condition showed an austenitic equiaxial microstructure with average grain size from 164 to 940 μm. Austenite, ferrite and kappa phases were detected by X-ray diffraction (XRD). Also, second-phase particles such as AlN, TiC and MnS were detected by LOM and SEM-EDS analysis. LD steel microalloyed with Ti/B exhibited the highest microhardness Vickers value (235 HV10) in the as-cast condition, whilst in the as-homogenized condition microhardness gradually decreases from 223 to 198 HV10 as holding time increases.

Metallographic, structural and mechanical characterization of low-density austenitic Fe-Mn-Al-C steels microalloyed with Ti/B and Ce/La in hot-rolling condition

MRS Advances ◽  
2019 ◽  
Vol 4 (57-58) ◽  
pp. 3087-3095
Author(s):  
C.E. Coronado-Alba ◽  
I. Mejía
Keyword(s):  
Grain Size ◽  
Hot Rolling ◽  
Mechanical Characterization ◽  
Research Work ◽  
Distribution Functions ◽  
Second Phase ◽  
Low Density ◽  
Second Stage ◽  
Rolling Condition

ABSTRACTLow-density austenitic Fe-Mn-Al-C steels have high strength, high ductility and a significant weight reduction respect to other alloyed steels. However, this complex system exhibits second-phase precipitation, particularly κ-carbide. It is well-known that the microalloying elements addition to steel generates precipitation hardening, as well as grain refinement effect. It is worth noting that low-density steels can cause cracking during hot-rolling due to high Mn, Al and C contents and segregation in grain boundaries. Hot-rolling conditions play an important role in the dynamic recrystallization mechanisms, and therefore in the austenitic grain size. The main objective of this research work is the metallographic, structural and mechanical characterization of low-density steels microalloyed with Ti/B and Ce/La in hot-rolling condition. For this purpose Fe-(27-30)Mn-(7-8)Al-(1.2-1.8)C (wt.%) low density steels microalloyed with Ti/B and Ce/La were hot-rolled at 1200 °C in two stages. Metallographic, structural and mechanical characterization was carried out by optical (LOM) and scanning electron (SEM) microscopies, electron backscatter diffraction (EBSD) through quality images, inverse pole figures (IPF) and orientation distribution functions (ODF) maps, X-ray diffraction (XRD) and microhardness Vickers (HV) testing. In general, the first stage of hot-rolling exhibits a strongly bimodal microstructure of dynamically recrystallized austenitic grains, while the second stage shows more uniform recrystallized grain size. In the first stage of hot-rolling the austenite is the predominant phase, while in the second stage the α-ferrite phase is barely visible. Low-density steel microalloyed with Ti/B presented better grain size and microhardness values compared to steel microalloyed with Ce/La. Preferred crystallographic orientations were not found.

Characterization of machined polystyrene foam

1989 ◽  
Vol 47 ◽  
pp. 372-373
Author(s):  
C. W. Price ◽  
E. F. Lindsey ◽  
R. M. Franks ◽  
M. A. Lane
Keyword(s):  
Surface Finish ◽  
Cell Walls ◽  
Surface Structures ◽  
Efficient Technique ◽  
Low Density ◽  
Polystyrene Foam ◽  
Planar Surfaces ◽  
Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

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