National Siluo Agricultural Industrial High School

Yunlin, Taiwan

National Siluo Agricultural Industrial High School

Yunlin, Taiwan
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Chang S.-H.,National Taipei University of Technology | Lee S.-C.,National Cheng Kung University | Huang K.-T.,National Siluo Agricultural Industrial High School
Materials Transactions | Year: 2010

In our previous work, the parameters of solid-solution treatment for 718 alloy were discussed. The results showed that a solution temperature of 1020°C is optimum. The Laves and S phase can complete solution after 1020°C, 1 h solid-solution treatment. The aim of this study is to discuss the effect of various aging treatments for as-HIP treated 718 alloy. In the experiment, seven different aging treatments were used: 720°C for 2,4, 8 and 16h, furnace cooled to 620°C, soak for 8h, and air cooled to room temperature; 720°C for 8h, furnace cooled to 620°C, soak for 2,4,8 and 16 h, and air cooled to room temperature. Experimental results showed that 1020°C solid-solution, 720°C for 8 h and 620°C for 4h of aging treatment for as-HIP treated 718 alloy is optimum. AU the precipitations are MC carbides; the dimension of γ" precipitations is 30.41 nm, which with a maximum tensile strength (1407.2MPa) and elongation (14.5%) at room temperature. © 2010 The Japan Institute of Metals.


Chang S.-H.,National Taipei University of Technology | Tang T.-P.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School
ISIJ International | Year: 2010

In this work, H13 tool steel was prepared with different oxidation treatments to investigate the effects of oxidation temperature and soaking time. In order to improve erosion and corrosion resistance, this study tested with oxidation temperatures of 560°C, 580°C, and 600°C, and oxidation soaking times of 1 h, 2 h, and 3 h, respectively. Experimental results showed that the oxidation treatment at 600°C and for 3 h is the optimum process. The average thickness of the oxide layer was 9.2 μm. It showed that the oxide layer (Fe 3O 4) can protect and improve the aluminum erosion of H13 steel. The specimens that underwent the oxidative procedure were proven to effectively reduce the ratio of Al-Fe-Si compounds during erosion tests of A380 alloy solution. In addition, the results showed that the oxide layer can enhance polarization resistance, and quickly generate a passivation layer to increase the ability of corrosion resistance. © 2010 ISIJ.


Chang S.-H.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School | Liu C.-M.,Lunghwa University of Science and Technology
International Journal of Cast Metals Research | Year: 2011

The effect of hot isostatic pressing (HIP) temperature on mechanical properties of 713LC cast superalloy was investigated; three temperatures (1453, 1468, 1483 K) were tested for a HIP soaking time of 2 h and pressure of 150 MPa. HIP treatment at1453 K was found to be optimal. Extensive c9 precipitation was observed and the optimal HIP treatment decreased porosity by ̃57.1%. Under tension testing at a fast strain rate (0.001 s-1), the tensile strength was increased by 5.2% at room temperature, 9.8% at 813 K and 7.9% at 923 K, whereas at a very slow strain rate (0.0001 s-1), tensile strength was increased by 1.2% at room temperature and 7.8% at 813 K. © 2011 W. S. Maney & Son Ltd.


Chang S.-H.,National Taipei University of Technology | Lee C.-W.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School | Wu M.-W.,National formosa University
Key Engineering Materials | Year: 2013

The experimental results indicated that the WC-12wt% Co specimens showed excellent mechanical properties and microstructure by the optimal sintering process. The G5 specimen sintered at 1400°C/1 h achieved a relative density of 98% and a hardness of HRA 88.5. Meanwhile, the TRS increased to 2400 MPa. F12 specimens that sintered at 1350°C/1 h achieved a relative density of 99% and a hardness of HRA 92.5. The TRS was also enhanced to 2170 MPa. In this study, the η phase (Co3W3C) precipitated at a high sintering temperature. The precipitations generated by liquid phase sintering gathered in some specific regions of the specimens and reacted with the WC particles. In addition, Co3W3C was a hard and brittle phase that resulted in a low TRS for the specimens; and a large amount of η phases were detrimental to the fracture toughness of the specimens. © (2013) Trans Tech Publications, Switzerland.


Chang S.-H.,National Taipei University of Technology | Lee S.-C.,National Cheng Kung University | Huang K.-T.,National Siluo Agricultural Industrial High School | Liang C.,National Taipei University of Technology
Applied Mechanics and Materials | Year: 2012

The aim of this study is to explore alloy 718 that treated at an optimal HIP process, and then imposed various solid-solution temperatures and aging treatment. The experimental results indicated that Laves and δ precipitations obviously appeared within the grain boundary, under HIP treatment and lower solid-solution temperatures (940°C), which would result in poor mechanical properties. However, Laves and δ phase can be completely dissolved at 1020°C 1 hour solid-solution treatment. The tensile strength was increased to 1331.5 MPa, and elongation reached up to 6.1% under a 1020°C solid-solution and aging treatment. Increasing the solid-solution temperature to 1060°C would cause parts of the NbC to dissolve, thus a large number of the thin sheet-shaped NbC would appear in the solid-solution and aging specimen. The yield stress is slight increase, but a lot of NbC precipitations will result in the decreasing tensile strength (1298.8 MPa) and elongation (5.4%). As a result, the optimal solid-solution treatment parameter of alloy 718 is 1020°C for 1-hour. © (2012) Trans Tech Publications.


Chang S.-H.,National Taipei University of Technology | Chen S.-H.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School
Materials Transactions | Year: 2012

Powder metallurgy is the conventional process for the production of CrCu alloys. Enhanced vacuum sintering techniques and the use of HIP processes can be applied to obtain higher densities and decreased porosity in the sintered parts. In this study, the optimal sintering process of Cr50Cu50 alloy targets is 1270°C for 1 h; a high density and low electrical resistivity of the alloy targets is obtained. The experimental results also indicate that the relative density of the Cr50Cu50 vacuum sintering targets can reach 99.42%, and that apparent porosity decreases to 0.54% after 1050°C at 175 MPa for 4 h of HIP treatments. The crystal property of sintered CrCu alloy is improved, and the resistivity decreased to 589 × 10 -8Ω.cm; IACS is also enhanced to 29.27% via HIP optimal treatment. This study shows that the high density and optimum properties of sintered Cr50Cu50 alloy targets can be produced by utilizing a suitable HIP treatment. © 2012 The Japan Institute of Metals.


Chang S.-H.,National Taipei University of Technology | Chen S.-H.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School | Liang C.,National Taipei University of Technology
Powder Metallurgy | Year: 2013

Owing to ingredient segregation, non-uniform microstructure and porosity defects in Cr-Cu alloys are frequently produced by melting process. Even subsequent heat treatment and hot working would not be able to completely resolve the problem. Therefore, this study investigated Cr60Cu40 alloy targets produced via vacuum sintering followed by hipping. Experimental results showed that the relative density of the sintered Cr60Cu40 alloy targets reached 99·69%, the apparent porosity decreased to 0·31% and transverse rupture strength increased to 553 MPa after hipping treatment at 1050°C at 175 MPa for 4 h. In addition, the closed pores were almost completely eliminated after the hipping treatment. The resistivity decreased to 643×10 -8 V cm, and the International Annealed Copper Standard value was enhanced to 26·81% after optimal hipping treatment. This study shows that hipping treatment can effectively eliminate internal pores of sintered Cr60Cu40 alloy targets and also improve their electrical properties. © 2013 Institute of Materials, Minerals and Mining.


Chang S.-H.,National Taipei University of Technology | Tang T.-P.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School | Tai F.-C.,National Tsing Hua University
Powder Metallurgy | Year: 2011

In this study, commercial VANADIS 4 (V-4) tool steel powders were classified by sifting, which was previously the matrix, and fine TiC powder was used as an additive to produce a new material with high hardness and wear resistance, via powder metallurgy and a sintering process. Experimental results showed that the transverse rupture strength of the original V-4 steel powder was 678·5 MPa and was enhanced to 868·6 MPa below 25 μm, after the addition of 35 wt-%TiC powders through sintering at 1400°C. In addition, the hardness increased to 86·2 HRA, transverse rupture strength reached 1059·3 MPa and porosity decreased to 1·2% of the V-4 steel powders (below 25 μm) added with 35 wt-%TiC after sintered at 1400μC and annealed at 850°C, followed by quenching at 1030°C and tempering at 200°C. © 2011 Institute of Materials, Minerals and Mining.


Chang S.-H.,National Taipei University of Technology | Lin Y.-K.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School
Surface and Coatings Technology | Year: 2012

In this study, the AISI H13 alloy steel specimens were subjected to various surface treatments including oxynitriding, TiAlN coating and duplex TiAlN/oxynitriding treatments. The experimental results indicated that a 0.04-0.05mm oxynitriding layer and 3-4μm TiAlN thin film could be successfully obtained after the duplex TiAlN/oxynitriding treatment. Due to the duplex surface treatment having the highest surface hardness (Hv 0.01=3463±1.5), the wear behavior results showed both the lowest weight loss (0.97g) and wear volume (0.047mm 3). Moreover, the higher hardness and high thermally stable properties of the TiAlN/oxynitriding duplex layer have the most effective erosion resistance in liquid A390 aluminum alloy compared to the other surface treatments. In addition, the corrosion test results also showed the duplex layer to have the lowest corrosion currents of 4.4169×10 -6 and 9.644×10 -5A, and highest polarization resistance of 4233.2 and 407.65Ω cm 2 in 3.5wt.% NaCl and 0.15M HCl solutions, respectively, signifying that the duplex treatment resulted in the best corrosion resistance. © 2012 Elsevier B.V.


Chang S.-H.,National Taipei University of Technology | Tang T.-P.,National Taipei University of Technology | Huang K.-T.,National Siluo Agricultural Industrial High School | Chen J.-K.,National Taipei University of Technology
ISIJ International | Year: 2012

This study conducted gas nitriding on AISI H13 steels, followed by oxidization treatments at various temperatures (560°C, 580°C, 600°C) and soaking times (1 h, 2 h, 3 h), to investigate the melting loss and corrosion resistance of A380 aluminum alloy. The experimental results indicated that the samples of oxynitriding (post-oxidizing treatment after nitrided) at 580°C for 3 h, 600°C for 2 h and 600°C for 3 h have better ability to resist melting loss due to their thicker oxidized layers. The weight loss rate also showed that they are near zero after a 4 h erosion test. The increasing weight loss rate is relative to the appearance of the Fe xAl ySi z compound. In addition, the difference in corrosion current is closely related to the corrosion rate. A smaller corrosion current will lead to a smaller corrosion rate. As a result, increasing the temperature and soaking time of oxidization is advantageous to the corrosion resistance, and a small variation in corrosion current will result in a significant change to the polarization resistance of corrosion. Consequently, the oxide layer can enhance the polarization resistance, and quickly generate a passivation layer that increases the corrosion resistance ability. © 2012 ISIJ.

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