Microstructure and mechanical properties of a high Nb-TiAl alloy fabricated by electron beam melting

Kan, Wenbin; Chen, Bin; Jin, Congrui; Peng, Hui; Lin, Junpin

doi:10.1016/j.matdes.2018.09.044

Cited by 85 publications

(35 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is well documented that M 2 C carbide is a metastable phase that can decompose into a mixture of M 6 C and MC carbides during high-temperature exposure. The carbide size observed in the EBM samples is much smaller compared to that of ingot casting [10] and similar to spray-forming. [24] For comparison purpose, the microstructure of a PM S390 steel sample in the fully heat-treated condition is shown in Figure 8(b).…”

Section: Carbide Precipitation and Volume Fractionmentioning

confidence: 74%

“…The microstructure refinement is very likely to be due to the applied localized high energy input combined with the rapid cooling rate when the electron beam sweeps over the melted region. The high cooling rates (10 4 to 10 7°C /s) during EBM process, as determined in previous EBM process modeling work, [10] are much higher than that of 0.1 to 5°C/s in ingot casting. [25] Microstructural refinement observed in as-EBM S390 arises primarily from the limited time for dendrite growth.…”

Section: A Microstructure Formation During Ebm Non-equilibrium Solidmentioning

confidence: 75%

“…More details about the EBM sample fabrication can be found elsewhere. [4,10] Table II summarizes these process parameters together with the calculated area energy E A , where E A = (IU)/(vL off ). U is the operating voltage and 60 kV was used.…”

Section: B Ebm Sample Fabricationmentioning

confidence: 99%

“…For example, EBM was applied to produce precipitation-strengthened nickelbase superalloys, [2][3][4][5][6] cobalt-base alloys, [7,8] as well as titanium aluminide intermetallic alloys. [9][10][11] However, little effort has been made regarding EBM high-speed steels that are also susceptible to cracking. Note the EBM work [12] on H13 steel that has a carbon content of 0.37 wt pct and limited degree of alloying does not represent those highly alloyed high-speed steels.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Jin

Gao

Peng

et al. 2020

Metall Mater Trans A

Self Cite

View full text Add to dashboard Cite

The solidified microstructure and carbide precipitation behavior in an S390 high-speed steel processed by electron beam melting (EBM) have been fully characterized. The as-EBM microstructure consists of discontinuous network of very fine primary carbides dispersed in auto-tempered martensite matrix together with a limited amount of retained austenite. The carbide network consists of M 2 C/M 6 C and MC carbides. Both the columnar and near-equiaxed grain structures were found in as-EBM microstructure and the presence of inter-dendritic eutectic carbides assisted in revealing the dendritic solidification nature. The top-layer microstructure observation confirmed that the columnar dendritic structured grains were located adjacent to the micro-melt pool boundary, indicating an epitaxial growth with the average growth direction parallel to the maximum thermal gradient. At the center of the micro-melt pool, the near-equiaxed grains were developed by dendritic growth parallel to the beam traveling direction. The carbide decomposition was revealed by scanning transmission electron microscopy and confirmed by transmission Kikuchi diffraction. The MC carbides (rich in V followed by W) nucleated at the interface between M 2 C (W, Fe, Mo, and Co in the order of significance) and the matrix and then grew from the outside inward, but their nucleation might occur from the M 2 C carbide itself. The thermal effect induced by the adjacent scan lines seems to trigger a solid-state phase transformation of MC fi M 2 C + c-Fe. The elemental migration was theoretically calculated and compared with the experimental results. The high hardness of~65 HRC and good transverse rupture strength of~2500 MPa in as-EBM S390 means that EBM processing can be used to fabricate highly alloyed tool steels. With the help of the post-processing heat treatment, the best Rockwell hardness of 73.1±0.2 HRC and transverse rupture strength of 3012±34 MPa can be obtained.

show abstract

Section: Carbide Precipitation and Volume Fractionmentioning

confidence: 74%

Section: A Microstructure Formation During Ebm Non-equilibrium Solidmentioning

confidence: 75%

Section: B Ebm Sample Fabricationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Jin

Gao

Peng

et al. 2020

Metall Mater Trans A

Self Cite

View full text Add to dashboard Cite

show abstract

“…The preheat process was done in two stages: base sintering and local sintering (referred to as preheat 1 and preheat 2). 16 Preheat 1 is applied to the whole build area (200 × 200 mm 2 ), and preheat 2 covers only the area to melt with 4-mm offset to the build area. Both preheats were applied with a beam current of 22 and 26 mA, respectively, using a defocused beam at relatively high speeds so the energy input is reduced enough to sinter powder particles prior to melting, that is, using a focus offset of 50 mA and 2500 mm/s.…”

Section: Manufacturing Of Test Samplesmentioning

confidence: 99%

Effect of postprocessing thermal treatments on electron‐beam powder bed–fused Ti6Al4V

Soundarapandiyan

Khan²,

Johnston

et al. 2020

Mat Design & Process Comms

View full text Add to dashboard Cite

Electron-beam powder-bed-fusion additive manufacturing was used to build Ti6Al4V blocks. Postfabrication thermal treatments were applied to modify the mechanical properties. The postfabrication treatments included hot isostatic pressing and solution treatment and ageing. The microstructure and mechanical properties of the as-built and postthermally treated material were characterised. The postfabrication treatments were found to be effective in homogenising the microstructure and reducing the number of defects/pores, which improved the material Charpy impact toughness and fatigue life with some reduction in the material's strength. Based on the present results, as well as data from previous literature studies, the reduction in material strength after the postthermal treatment is likely to be caused by the combined effect of α-lath coarsening and the low oxygen content of the powder feedstock.

show abstract

Gas atomization of γ‐TiAl Alloy Powder for Additive Manufacturing

2019

View full text Add to dashboard Cite

The aim is, first, to optimize gas atomization of a γ‐TiAl alloy at the laboratory scale (atomized mass < 150 g) and, second, to investigate the microstructure of the produced powders. Gas atomization variables, such as the gas pressure and the melt temperature, are adjusted to produce the highest yield of particles with sizes smaller than 150 μm. The morphology and microstructure of these powders is characterized by scanning electron microscopy, as well as electron backscattered diffraction. The fine particles of interest are found to be single α2 polycrystals with spherical shape and negligible porosity. Overall, these particles meet the morphological requirements of raw powders for additive manufacturing powder‐based methods, provided the small loss of Al that takes place during melting is compensated by increasing the amount of this component in the starting alloy.

show abstract

Microstructure and mechanical properties of a high Nb-TiAl alloy fabricated by electron beam melting

Cited by 85 publications

References 32 publications

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Effect of postprocessing thermal treatments on electron‐beam powder bed–fused Ti6Al4V

Gas atomization of γ‐TiAl Alloy Powder for Additive Manufacturing

Contact Info

Product

Resources

About