Effect of MIM Process Conditions on Microstructures and Mechanical Properties of Ti-6Al-4V Compacts.

Maekawa, Kazuyuki; Takita, Mituharu; Nomura, Hiroyasu

doi:10.2497/jjspm.46.1053

Cited by 10 publications

(3 citation statements)

References 2 publications

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“…Titanium component production by the metal powder injection molding process (Ti-MIM) was the subject of much effort over the past few decades with several reports showing the incremental steps in powders, binders, debinding, sintering, and post-sintering details [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,…”

Section: Introductionmentioning

confidence: 99%

Progress in Titanium Metal Powder Injection Molding

German

2013

Materials

147

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Metal powder injection molding is a shaping technology that has achieved solid scientific underpinnings. It is from this science base that recent progress has occurred in titanium powder injection molding. Much of the progress awaited development of the required particles with specific characteristics of particle size, particle shape, and purity. The production of titanium components by injection molding is stabilized by a good understanding of how each process variable impacts density and impurity level. As summarized here, recent research has isolated the four critical success factors in titanium metal powder injection molding (Ti-MIM) that must be simultaneously satisfied—density, purity, alloying, and microstructure. The critical role of density and impurities, and the inability to remove impurities with sintering, compels attention to starting Ti-MIM with high quality alloy powders. This article addresses the four critical success factors to rationalize Ti-MIM processing conditions to the requirements for demanding applications in aerospace and medical fields. Based on extensive research, a baseline process is identified and reported here with attention to linking mechanical properties to the four critical success factors.

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Section: Introductionmentioning

confidence: 99%

Progress in Titanium Metal Powder Injection Molding

German

2013

Materials

147

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“…Specially, the proeutectoid ferrite film around the austenite grain boundary of the tensile sample at 800 °C forms a complete ring with thicker size than that at 850 °C due to longer phase transformation time, which is in accordance with the equilibrium phase transition temperatures A e3 of 840 °C, as shown in Table 2. What is more, a small amount of intermittent or continuous proeutectoid ferrite film in the fracture of the tensile sample at 800 °C, as shown in Figure 9e, has very low strength, only a quarter of the austenite strength, [ 21,29,30 ] this results in stress concentration in the thin films of ferrite of the tensile samples, finally decreases remarkably the RA of the tensile samples, as shown in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

Hot Ductility Evolution Mechanism of Titanium‐Bearing Microalloyed Steels

Liu

Zheng

et al. 2023

steel research int.

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Titanium‐bearing (Ti‐bearing) microalloyed steels have high strength and toughness by grain refinement effect of carbonitride precipitates. However, they can induce surface cracks of continuous casting slab when the Ti alloyed content is high. A microalloyed steel with Ti content (0.10–0.15 wt%) is carried out by thermalmechanical simulator over 600–1350 °C to analyze hot ductility evolution mechanism. Fracture surface morphology, phase transition, and behavior of precipitates of the tensile samples are investigated by experimental detection and thermodynamic calculation. The ductility–temperature curves show that the third brittle temperature range is 600–890 °C, which is mainly attributed to the thin proeutectoid ferrite film and precipitated titanium carbonitride particles, widening the embrittlement temperature ranges through of steel. In addition, the tensile samples at 890–1350 °C have good hot ductility, indicating the dynamic recrystallization of deformed austenite can trigger grain boundaries migration away from cracks and avoid the side effect of the Ti (C,N) particles on hot ductility. The first brittle temperature range of 1350 °C‐melting point is mainly ascribed to the partial melting of the grain boundaries with element segregation of sulfur and phosphorus, and microporosity loose among dendrites.

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“…If sintering for a long time in the α + β region is carried out without pressurizing (unlike capsule HIP), a sufficiently dense sintered compacts with an equiaxed microstructure may be obtained. So far there are few reports (Maekawa et al, 1999) on the sintering of Ti alloys in the α + β region. Although tensile strength has been studied, there is no report to evaluate fatigue strength.…”

mentioning

confidence: 99%

Effect of α + β region sintering on the mechanical properties of injection molded Ti-6Al-4V compacts

Kudo

Shinagawa

Miura

2018

Mechanical Engineering Journal

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IntroductionThe titanium alloys have superior advantages such as high specific strength, high corrosion resistance and heat resistance. They are used in medical, aerospace and other fields (Niinomi, 2001). However, their poor workability involves the high cost by removal processing. According to the powder metallurgy, titanium alloy parts can be produced in the near net shape, which is effective in reducing the processing cost.Among many types of powder metallurgy, metal injection molding (MIM) process is an advantageous technique for the production of complex shaped parts. In addition, it is possible to manufacture metal parts with higher mechanical properties than that of the press sintered material because of high density using fine powder. Injection molded Ti-6Al-4V alloy compacts have been studied extensively for applications of MIM process (Noda et al., 2011)(Ferri et al., 2009)(Ferri et al., 2010 . Generally, injection molded Ti-6Al-4V compacts show sufficient static mechanical properties (tensile strength and ductility) comparable to that of the wrought material. The fatigue strength, however, is significantly lower than that of wrought material. One of the reasons for low endurance is the existence of residual pores, but the principal factor is the coarse lamellar microstructure in normal sintered compacts. The microstructures of the wrought material and the MIM sintered compacts are shown in Fig.1, respectively. The equiaxed fine microstructure of the wrought material is produced by hot plastic working in the α + β temperature region, which brings about high strength-elongation balance (Matthew and Donachie, 1988) and high fatigue strength. On the other hand, so-called lamellar microstructure, in which α phase is precipitated in a layered manner in β phase, was observed in Effect of α + β region sintering on the mechanical properties of injection molded Ti-6Al-4V compacts ， Kentaro KUDO* Kazunari SHINAGAWA** and Hideshi MIURA*** AbstractInjection molded Ti-6Al-4V compacts have normally a coarse lamellar microstructure, because it is sintered above the  transus temperature and it is cooled slowly in furnace. However, static mechanical properties such as tensile strength and ductility are equivalent to those of wrought materials, but they have the disadvantage that the fatigue strength is significantly lower than wrought materials. Therefore, improvement of fatigue strength is needed for injection molded Ti alloy compacts. In this study, injection molded Ti-6Al-4V compacts having equiaxed microstructure were prepared by sintering at α + β region temperature which is very lower than normal sintering temperature. When sintering is carried out in α + β region, sinterability is remarkably poor. Therefore, long-time sintering is required. Since the grain growth of the prior β grains was suppressed by the pinning effect of α grains and pores, it was possible to obtain the significantly fine grains as compared with the β region sintered compacts. The α + β region sintered compacts showed high strength, high e...

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Effect of MIM Process Conditions on Microstructures and Mechanical Properties of Ti-6Al-4V Compacts.

Cited by 10 publications

References 2 publications

Progress in Titanium Metal Powder Injection Molding

Progress in Titanium Metal Powder Injection Molding

Hot Ductility Evolution Mechanism of Titanium‐Bearing Microalloyed Steels

Effect of α + β region sintering on the mechanical properties of injection molded Ti-6Al-4V compacts

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