Chinese Journal of Lasers, Volume. 47, Issue 12, 1202005(2020)
Research Progress of Selective Laser Melting of Nitinol
Figures & Tables(17)
![Transformation temperatures increase with the increase of energy density[14]. (a) Cooling process; (b) heating process](/Images/icon/loading.gif){kind=icon}
Fig. 4. Transformation temperatures increase with the increase of energy density[14]. (a) Cooling process; (b) heating process
Table 1. Particle size and composition of frequently used NiTi powder
View tableTable 1. Particle size and composition of frequently used NiTi powder
Powder Particle size /μm Reference Ni49.7Ti50.3 25--75 [14] Ni50.0Ti50.0 20--45 [15] Ni50.1Ti49.9 25--75 [16] Ni50.2Ti49.8 25--75,25--45 [14],[17] Ni50.6Ti49.4 25--45 [18] Ni50.7Ti49.3 25--75 [14] Ni50.8Ti49.2 25--75 [19-20] Ni50.9Ti49.1 35--180 [21]
Table 2. Suitable process parameters of selective laser melting of nitinol
View tableTable 2. Suitable process parameters of selective laser melting of nitinol
Material Application P/W v/ (mm·s-1) t/μm E/(J·mm-3) Reference Ni50.1Ti49.9 Energy absorber and biomedical implants 250 1250 30 55.6 [16] Ni50.1Ti49.9 Scaffolds 250 1100 -- 126.0 [29] Ni50.8Ti49.2 Biomedical implants 250 1250 30 83.3 [20] Ni49.9Ti50.1 Stressed skeleton 50 100 -- -- [30] Ni49.9Ti50.1 Scaffolds 50 160 -- -- [30] Ni49.7Ti50.3 Carrier material for human mesenchymal stem cells 100 -- 75 -- [31]
Table 3. Transformation temperatures related to different process parameters
View tableTable 3. Transformation temperatures related to different process parameters
Material P/W v/ (mm·s-1) t/μm E/(J·mm-3) Ms/K Mf/K As/K Af/K Reference Ni50.1Ti49.9 250 1250 30 55.6 331 299 332 358 [16] Ni50.2Ti49.8 250 1100 30 126.3 261 -- 296 -- [17] Ni50.8Ti49.2 100 125 30 222.2 293 -- 276 -- [19] 100 175 30 158.7 280 -- 260 -- 100 225 30 123.4 277 -- 252 -- 100 500 30 55.5 275 -- 251 -- 250 875 30 79.4 315 -- 287 -- 250 1000 30 69.4 310 -- 282 -- 250 1250 30 55.5 308 -- 280 -- Ni50.8Ti49.2 250 1250 30 83.3 247 -- 285 -- [20] 250 1250 30 66.7 243 -- 279 -- 250 1250 30 55.6 242 -- 277 -- 250 1250 30 47.6 241 -- 276 -- 250 1250 30 41.7 239 -- 274 -- 250 1250 30 37.0 237 -- 269 -- 250 1500 30 46.3 300 -- 275 -- Material P/W v/ (mm·s-1) t/μm E/(J·mm-3) Ms/K Mf/K As/K Af/K Reference Ni50.9Ti49.1 56 133 -- 70.0 289 220 245 311 [21] 68 133 -- 85.0 283 225 262 302 80 133 -- 100.0 291 236 267 313 92 133 -- 115.0 286 233 267 305 100 133 -- 125.0 286 215 253 305 80 297 -- 45.0 273 189 236 275 80 224 -- 60.0 270 192 239 278 80 190 -- 70.0 274 212 257 288 80 157 -- 85.0 282 229 262 300 80 133 -- 100.0 289 234 263 310 80 116 -- 115.0 296 244 280 320 80 107 -- 125.0 294 232 274 313 Ni50.9Ti49.1 50 80 30 595.2 335 320 329 361 [27] 50 80 30 173.6 330 271 306 355
Table 4. Influence factors on transformation temperatures of nitinol
View tableTable 4. Influence factors on transformation temperatures of nitinol
Factor Influence Energy density Transformation temperatures usually increase with the increase of energy densities within limits High or low laser power and scanning speed(with similar E) Transformation temperatures are usually lower in samples formed by high laser power and scanning speed Annealing For Ni-rich NiTi,transformation temperatures usually increase after proper annealing, but precipitation formed in annealing should also be considered Solution For Ni-rich NiTi,transformation temperatures decrease after solution Aging For Ni-rich NiTi,transformation temperatures increase after aging Impurity elements When combined with Ti,transformation temperatures decrease
Table 5. Influence factors on shape memory effect of nitinol
View tableTable 5. Influence factors on shape memory effect of nitinol
Factor Influence Transformation temperatures Shape memory effect seems better when transformation temperatures are higher Porosity and crack Shape memory effect will be severely weakened due to these defect Annealing Some austenites will transform to martensites, which made the reversible phase change happen more easily,so shape memory effect will become better Solution Some Ni-rich phases will dissolve into the matrix and make the part stronger, so the critical stress will increase and shape memory effect will become better Aging High density fine Ni4Ti3 will form and the strength of the part will increase, so the critical stress will increase and shape memory effect will become better Impurity elements Shape memory effect will be severely weakened due to these impurity elements
Table 6. Influence factors on superelasticity of nitinol
View tableTable 6. Influence factors on superelasticity of nitinol
Factor Influence Transformation temperatures Superelasticity seems better when transformation temperatures are lower Porosity and crack Superelasticity will be severely weakened due to these defects Strong texture Superelasticity will be better when strong texture formed in certain direction Fabricating direction Superelasticity is better when the NiTi part is fabricated perpendicular to the loading direction Solution Some Ni-rich phases will dissolve and be reborn in the grain and the increase of Ni in matrix will make the part stronger, so the critical stress will increase and superelasticity will become better Aging High density fine Ni4Ti3 will form and the strength of the part will increase, so the critical stress will increase and superelasticity will become better Impurity elements Superelasticity will be severely weakened due to these impurity elements
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Hu Zehua, Song Changhui, Liu Linqing, Yang Yongqiang, Hu Ping. Research Progress of Selective Laser Melting of Nitinol[J]. Chinese Journal of Lasers, 2020, 47(12): 1202005
Paper Information
Category: laser manufacturing
Received: Jun. 15, 2020
Accepted: --
Published Online: Nov. 26, 2020
The Author Email: Changhui Song (chsong@scut.edu.cn)
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