材料科学与技术 ›› 2020, Vol. 39 ›› Issue (0): 144-154.DOI: 10.1016/j.jmst.2019.08.026
-
收稿日期:2019-06-18修回日期:2019-07-29接受日期:2019-08-12出版日期:2020-02-15发布日期:2020-03-11
Cracking behavior and control of β-solidifying Ti-40Al-9V-0.5Y alloy produced by selective laser melting
Piao Gaoa, Wenpu Huanga, Huihui Yanga, Guanyi Jinga, Qi Liub, Guoqing Wangb, Zemin Wanga*(
), Xiaoyan Zenga
- a Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
b China Academy of Launch Vehicle Technology, Beijing 100076, China
-
Received:2019-06-18Revised:2019-07-29Accepted:2019-08-12Online:2020-02-15Published:2020-03-11 -
Contact:Wang Zemin
引用本文
. [J]. 材料科学与技术, 2020, 39(0): 144-154.
Piao Gao, Wenpu Huang, Huihui Yang, Guanyi Jing, Qi Liu, Guoqing Wang, Zemin Wang, Xiaoyan Zeng. Cracking behavior and control of β-solidifying Ti-40Al-9V-0.5Y alloy produced by selective laser melting[J]. J. Mater. Sci. Technol., 2020, 39(0): 144-154.
Fig. 1. Ti-40Al-9V-0.5Y powders: (a) particle morphology, (b) particle size distribution.
| Parameters | Value |
|---|---|
| Laser power P (W) | 200 |
| Scanning velocity V (mm/s) | 100-1000, with a step of 100 |
| Hatch spacing S (mm) | 0.08 |
| Layer thickness δ (μm) | 50 |
| Phase angle (degree) | 90 |
Table 1 Processing parameters applied in experiments.
| Parameters | Value |
|---|---|
| Laser power P (W) | 200 |
| Scanning velocity V (mm/s) | 100-1000, with a step of 100 |
| Hatch spacing S (mm) | 0.08 |
| Layer thickness δ (μm) | 50 |
| Phase angle (degree) | 90 |
Fig. 2. Measure methods to determine the solidification time of liquid-state molten pools. (a) The laser melts powders at point A (t0); (b) point A is still in liquid state as the laser moves to point B at t0+14.71 ms; (c) point A just solidifies at t0+22.79 ms; (d) the solidified state of point A remains unchanged at t0+26.94 ms.
| V (mm/s) | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 | 1000 |
|---|---|---|---|---|---|---|---|---|---|---|
| ts (ms) | 39.75± 1.29 | 22.79 ± 5.35 | 3.53 ± 0.25 | 2.92± 0.13 | 2.49 ± 0.09 | 2.14 ± 0.07 | 1.26 ± 0.04 | 1.03 ± 0.06 | 0.70 ± 0.02 | 0.57 ± 0.05 |
Table 2 The average ts under different scanning velocities.
| V (mm/s) | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900 | 1000 |
|---|---|---|---|---|---|---|---|---|---|---|
| ts (ms) | 39.75± 1.29 | 22.79 ± 5.35 | 3.53 ± 0.25 | 2.92± 0.13 | 2.49 ± 0.09 | 2.14 ± 0.07 | 1.26 ± 0.04 | 1.03 ± 0.06 | 0.70 ± 0.02 | 0.57 ± 0.05 |
Fig. 3. Surface morphologies, metallographic photographs and molten pool characteristics of the cylinder samples deposited at different scanning velocities. (a, d, g) 100 mm/s≤V≤200 mm/s; (b, e, h) 200 mm/s<V≤500 mm/s; (c, f, i) 500 mm/s<V≤1000 mm/s. (Note that red dotted line represents the boundary of molten pool.).
Fig. 4. Crack density and porosity of SLM-processed samples deposited at different scanning velocities.
Fig. 5. Aspect ratios of molten pools deposited at different scanning velocities (the insert displays the corresponding depth and width of molten pools).
| Thermo-physical parameters | Value | Ref. |
|---|---|---|
| Density ρ (kg/m3) | 3800 | [ |
| Thermal conductivity K (W·m-1·K-1) | 14.9 | [ |
| Specific heat capacity C (J·kg-1·K-1) | 650 | [ |
| Boiling point Tb (K) | 3315 | [ |
| Laser absorption coefficient A | 0.25 | [ |
Table 3 Thermal-physical properties of γ-TiAl alloy.
| Thermo-physical parameters | Value | Ref. |
|---|---|---|
| Density ρ (kg/m3) | 3800 | [ |
| Thermal conductivity K (W·m-1·K-1) | 14.9 | [ |
| Specific heat capacity C (J·kg-1·K-1) | 650 | [ |
| Boiling point Tb (K) | 3315 | [ |
| Laser absorption coefficient A | 0.25 | [ |
Fig. 6. Cooling rates in molten pools under different scanning velocities. ($\dot{T}_{max}$: the cooling rate in the center of molten pool.).
Fig. 7. Microstructures and phase characteristics of molten pools for cracking and crack-free samples. (a, d) SEM images (red dotted line represents the boundary of molten pool); (b, e) Inverse pole figures (IPFs) for zones marked by the blue and yellow rectangles, respectively; (c, f) phase maps corresponding to b and e, respectively. (Note that red, blue, and yellow represents the B2, α2 and γ phases, respectively.).
Fig. 8. (a) Section of Ti-Al binary phase diagram (the red dotted line shows the solidification path of Ti-40Al); (b) XRD spectra of the crack-free and cracking cylinder samples.
Fig. 9. EPMA maps of element distribution for the crack-free sample.
Fig. 10. Pole figures (PFs) corresponding to the zones marked by the yellow rectangle in Fig.7(d) for the crack-free sample. (a) β0-TiAl (B2) phase; (b) α2-Ti3Al phase; (c) γ-TiAl phase.
Fig. 11. Schematic illustration of cracking behavior and crack inhibition mechanism for SLM-processed Ti-40Al-9V-0.5Y alloy.
Fig. 12. Microhardness distributions in the directions of X, Y and 45° for the crack-free sample deposited at 200 mm/s.
Fig. 13. (a) Compression stress-strain curves of the three crack-free Ti-40Al-9V-0.5Y samples at 200 mm/s. (b) Compression properties of the crack-free SLM-processed Ti-40Al-9V-0.5Y alloy, the as-cast and SLM-processed TNM alloys.
Fig. 14. SEM images of compression fracture surface for the crack-free sample at (a) a low magnification, and (b) a high magnification.
|
| No related articles found! |
| 阅读次数 | ||||||
|
全文 |
|
|||||
|
摘要 |
|
|||||