Cr5Ti6aL4V Metal Injection Molding Parts

May 18, 2023

Qinhuangdao Zhongwei Precision Machinery Co., Ltd. specializes in producing Cr5Ti6aL4V Metal Injection Molding Parts, pure titanium metal injection molding parts. The company has been continuously testing and testing since 2008, and officially achieved mass production in 2012. We hope to solve your problem and work together to create a bright future. If you need it, please send us an email: business-mall@zw-jm.com

Preface

Titanium and its alloys have properties such as low density, high strength, good high-temperature strength, and excellent corrosion resistance, and are widely used in aerospace, automotive, bioengineering (good compatibility), watches, environmental protection, and other fields. However, the poor machining performance of titanium and its alloys has become an obstacle to the mass production of complex shaped parts. Therefore, the production of titanium parts using a new metal injection molding (MIM) process is highly anticipated. This article summarizes the research status of MIM titanium alloys, in order to facilitate the development of MIM titanium parts and market expansion.

2 Titanium powder

The production methods of titanium powder include hydrogenation titanium decomposition and fragmentation (HDH) or gas atomization (GA). To prepare titanium alloy powder, the titanium powder obtained by the above method can be mixed with other metal powders, or the titanium alloy powder can be directly prepared by GA or high-temperature self combustion method.

3MIM Titanium

The compacted density of HDHTi powder is lower than that of GATi powder. When preparing injection materials, the bonding dosage (volume fraction) is 43.1% and 33.3% respectively. The adhesive used is resin and wax. Mix the binder and Ti powder at a temperature of 383393K for 1 hour. After injection molding, the formed billet undergoes thermal decomposition and debonding in a 102Pa vacuum in an Ar gas flow and at 648K. The heating rate between 423573K is 1.4 × 10-5Ｋ/ｓ。 About 90% of the binder in the injection molded blanks of the above two powders can be removed. Then sintered in 10-2Pa vacuum at a heating rate of 5.56 × 10-2Ｋ/ｓ。 Hold at sintering temperature for 2 hours. The relative density of HDH powder injection molded blanks sintered at 1198K was 82.4%, and rapidly increased to 94.5% after sintering at 1348K. The powder loading in the atomized Ti powder injection material is large. The relative density of the injection formed billet after sintering at 1198K reaches 92.4%, 94.8% at 1248K, and 95.8% at 1348K. The sintering temperature increased from 1198K to 1348K, and the tensile strength of sintered Ti prepared from atomized titanium powder increased from 550MPa to 610MPa, only increasing by 60MPa. However, the sintered Ti prepared from HDH titanium powder increased from 420MPa to 630MPa, increasing by 210MPa. It is worth noting that after sintering at 1298K, although the relative density of HDHTi powder produced was 92%, which was lower than that of titanium powder produced by atomization (95%), the tensile strength of HDHTi powder produced (630MPa) was 40 MPa higher than that of titanium powder produced by atomization (590MPa). The variation pattern of their yield strength is similar to that of their tensile strength. The elongation of the Ti powder prepared by atomization after sintering at 1223K1298K is about 15% to 20%. But when the sintering temperature is higher than 1323K, the elongation sharply decreases to 5%. The elongation of HDHTi powder prepared is generally lower than that of titanium powder prepared by atomization, and it is 6% 7% after sintering at 1273 to 1298 K. Chemical analysis data shows that the carbon content after sintering from HDHTi powder is 0.06% 0.07%,

It is slightly higher than the 0.05% and 0.06% obtained from atomized Ti powder, and will not have any impact on mechanical properties. However, the oxygen content is 0.45%, 0.46%, and 0.28% respectively, which is an important factor affecting mechanical properties. To reduce the oxygen content of MIMTi, low oxygen content (0.13%) atomized Ti powder with an average particle size of 23.81 was used μ m) Use low oxygen content polypropylene, paraffin, and Carnauba wax as binders. Mix under pressure with 70% (volume fraction) Ti powder at 447K for 1 hour. After injection molding, solvent extraction was performed at 313K for 0.5h to remove 43% and 61% of the binder. The remaining binder was then removed in the Ar airflow under vacuum at 773K, which can prevent oxidation and carbonization. On (12) × High temperature sintering at 14231503K in 10-2Pa vacuum for 1.5 hours. The results indicate that the oxygen and carbon contents of MIMTi prepared from binders with different composition ratios are different. When using 40% polypropylene+60% wax binder, the oxygen content of Ti obtained after 1443K sintering for 1.5 hours is the lowest, at 0.22% (C0.04% N0.0017%). At this point, the elongation is 19%（ σ Is 504MPa σ 0.2 is 360MPa). When the sintering temperature is increased to 1463K, the oxygen content decreases to 0.20% and the elongation reaches the highest value (21.5%). Continuing to increase the sintering temperature to 1503K, although the density increased to 96.4%, the elongation sharply decreased to 4% 5%. The reason is that the oxygen content increases to 0.3% and the grains are coarsened. Therefore, 14431463K is the optimal sintering temperature. At this point, the performance of MIMTi meets the TypeJIS3 standard (O ≤ 0.3%, N ≤ 0.007% σ= 451617ＭＰａ、 σ 0.2≥343ＭＰａ、 δ≥ 18%)。

6MIMTi Mo alloy

Ti-12Mo is β Phase stable alloy with excellent corrosion resistance and high strength. Using atomized Ti powder (particle size less than 38 μ m) And molybdenum powder (average particle size 0.6 μ m) Mix for 10 hours in a double cone mixer. Then mix and granulate with 13.4% (mass fraction) binder. The binder is composed of polymer and wax. The polymer is composed of polypropylene, high-density polyethylene, and copolymers of ethylene and EVA, while the wax is composed of microcrystalline paraffin and Carnauba wax. Injection molding at a temperature of 473K and a pressure of 100MPa. At (12) × Under a vacuum of 10-1Pa, 96% of the adhesive can be removed at 673K for 5 hours, and then at 13931573K, (12) × Sintering in 10-1Pa vacuum. As the sintering temperature increases, the density linearity increases, and the relative density reaches the highest at 1573K, reaching 97% (forging density of 4.88g/cm3). Such a high sintering temperature can increase density, but due to the removal of residual carbon by the binder, TiC precipitates at grain boundaries, and the grains grow, resulting in a decrease in strength. Mechanical performance tests indicate that,

When sintered at 14731493K for 2 hours (relative density of 94.1%) and 14331473K for 5 hours (density of 95.1%), the tensile strength reached the highest, reaching 1000MPa, fully achieving the same composition as melting and forging β- The level of Ti alloy.

7 Conclusion

Ti and Ti alloys have low density, high strength, good high-temperature performance, and excellent corrosion resistance, making them highly promising structural materials. But it's difficult to machine. MIM has become a production process for producing complex shaped products of Ti and Ti alloys. Element mixed powder or pre alloy powder can be used to debond in Ar gas flow and sintered in real air, with a relative density of over 95%. The tensile strength of MIM pure Ti reaches 630MPa and the elongation is 20%. The tensile strength of MIMTi Al is 430MPa, especially at 800 ℃, the high temperature strength remains at 330MPa and the elongation is 13%. The tensile strength of MIMTi-6Al-4V reaches 10001300MPa and the elongation is 12%. The tensile strength of MIMTi Mo is 1000MPa. The properties of Ti and Ti alloys formed by metal injection molding have completely reached the level of melting and forging materials with the same composition.