Viscous Behaviours of Feedstocks for Micro MIM

2011 ◽  
Vol 314-316 ◽  
pp. 713-718 ◽  
Author(s):  
Zhi Qiang Cheng ◽  
Cedric Quinard ◽  
Xiang Ji Kong ◽  
Thierry Barriere ◽  
Bao Sheng Liu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Gradual Increase ◽  
Heating Temperature ◽  
The Self ◽  
Metal Injection Molding ◽  
Powder Size ◽  
Capillary Rheometer ◽  
Binder Composition

The viscous behavior of feedstocks plays the crucial role in Micro MIM. It affects directly injectability of the components and finally quality of the sintered component, because of the possible segregation induced by injection. The studies on viscosity of the feedstocks are realized by a series of the tests, in which a torque rheometer and a capillary rheometer are employed. The effects of binder composition, powder size, temperature and powder loading in volume on viscosity of the feedstocks are investigated. The mixtures of three kinds of binder composition, mixed with 5µm or 16µm 316L stainless steel powders, are evaluated. The best binder composition is determined by comparison of the viscous behaviors among the self-mixed feedstocks and the commercial one. It results in the suitable ranges of heating temperature and powder loading in volume for the feedstocks. The critical powder loading in volume is determined by a series of the capillary tests with the gradual increase of powder loading. These works provide the valuable reference for the research on binder composition and the process of micro metal injection molding.

scholarly journals Oxide Formation In Metal Injection Molding Of 316L Stainless Steel

2015 ◽  
Vol 60 (2) ◽  
pp. 1281-1285
Author(s):  
Jin Man Jang ◽  
Wonsik Lee ◽  
Se-Hyun Ko ◽  
Chulwoong Han ◽  
Hanshin Choi
Keyword(s):  
Stainless Steel ◽  
Grain Growth ◽  
316L Stainless Steel ◽  
Steel Powder ◽  
Hydrogen Atmosphere ◽  
Metal Injection Molding ◽  
Powder Size ◽  
Oxide Particles ◽  
Micro Features ◽  
Sintering Condition

Abstract The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.

The Characterization and Flow Behavior of 316L Stainless Steel Feedstock for Micro Metal Injection Molding (μMIM)

2010 ◽  
Vol 44-47 ◽  
pp. 2872-2876
Author(s):  
Pei Li Haw ◽  
Norhamidi Muhamad ◽  
Hadi Murthadha
Keyword(s):  
Stainless Steel ◽  
Injection Molding ◽  
316L Stainless Steel ◽  
Flow Behavior ◽  
Palm Stearin ◽  
Metal Injection Molding ◽  
Injection Molding Process ◽  
Binder System ◽  
Molding Process ◽  
Rheological Characterization

The rheological behaviors of the Micro Metal Injection Molding feedstock are important for the stability of the feedstock during micro injection molding process and quality of the final micro-components. Homogeneous feedstocks are preferable for MIM process to ensure the dimensional consistency of molded components and prevent the defects of powder-binder separation or particle segregation. In this work, feedstocks with various formulations of 316L stainless steel and binder system were prepared by using Brabender Plastograph EC Plus mixer. The binder system comprises of palm stearin, polyethelene (PE) and stearic acid. In order to obtain the viscosity, activation energy, flow behavior and mold ability index, the rheological characterization of the feedstocks were investigated in numerous conditions by using Shimadzu 500-D capillary rheometer The study showed that all of the 316L stainless steel feedstocks are homogenous with pseudo-plastic behaviors.

Characterization and Rheological Studies on Ready-Made Feedstock of Stainless Steel 316L in Metal Injection Molding (MIM) Process

2013 ◽  
Vol 465-466 ◽  
pp. 709-714 ◽  
Author(s):  
N.H. Mohamad Nor ◽  
Muhammad Hussain Ismail ◽  
Nur Atikah Abu Kasim ◽  
N. Muhamad ◽  
M.A. Taib
Keyword(s):  
Stainless Steel ◽  
Current Trend ◽  
Metal Injection Molding ◽  
Total Weight Loss ◽  
Capillary Rheometer ◽  
Stainless Steel 316L ◽  
Flow Behaviour Index ◽  
Crucial Part ◽  
Advanced Applications ◽  
Behaviour Index

Current trend for manufacturers associated to MIM industry try to enhance the feedstock in term of its characteristics, since it is the most crucial part of the MIM process. This paper covered the characterization and rheological studies on a ready-made feedstock of stainless steel 316L which is vital to determine the availability and suit the needs of many advanced applications. There are three different experiments involved which are Scanning Electron Microscope (SEM), Differential Scanning Calorimeter (DSC), Thermogravimetric (TGA) and Capillary Rheometer. Observation through SEM gives an insight of the bonding microstructure matrices of the feedstock and also determines the homogeneity of the feedstock. DSC testing defines the melting temperature of the 3 binders used which are 62.07°C for surfactant, 178.72°C for filler and 236.61°C for backbone binder. From TGA result, it showed that the total weight loss of feedstock was 39%. Throughout the capillary rheometer testing, the feedstocks viscosity was decreasing as the shear rate increasing. The feedstock exhibits pseudoplastic behaviour since its flow behaviour index was less than 1. It is founded that at the temperature of 190°C, the feedstock exhibits the best characteristics for injection.

scholarly journals On the Microstructures and Fatigue Behaviors of 316L Stainless Steel Metal Injection Molded with Gas- and Water-Atomized Powders

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 893 ◽  
Author(s):  
Yongyun Zhang ◽  
Ensheng Feng ◽  
Wei Mo ◽  
Yonghu Lv ◽  
Rui Ma ◽  
...  
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Fatigue Cracks ◽  
Selective Laser Sintering ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Metal Injection Molding ◽  
Strengthening Effect ◽  
Lower Oxygen ◽  
Order Of Magnitude

316L stainless steel samples are fabricated by metal injection molding using water-atomized and gas-atomized powder with different oxygen contents. The influences of oxygen on the microstructural evolution and fatigue properties of the samples are investigated. The oxygen tends to react with Mn and Si to form oxide particles during sintering. The oxides hamper the densification process and result in decreased sintered density. Moreover, their existence reduces the Mn and Si dissolving into the base metal and compromises the solution strengthening effect. The oxides lead to stress concentration in the tensile and fatigue tests and become the initiation sites of fatigue cracks. After sintering, the samples made from the gas-atomized powder have a much lower oxygen content compared to those made from the water-atomized powder, therefore, exhibiting much better mechanical properties. The tensile strength, yield strength and the elongation of the samples made from the gas-atomized powder are 560 MPa, 205 MPa, and 58%, respectively. Their fatigue lives are about one order of magnitude longer than the samples made from water-atomized powder, and also longer than those fabricated by powder metallurgy and selective laser sintering which were reported in other studies.

Influence of the Temperature in the Direct Forming Laser Process of 316L Stainless Steel with CO2 Laser

2014 ◽  
Vol 802 ◽  
pp. 334-337
Author(s):  
C.L. Santos ◽  
G. Vasconcelos ◽  
H.S. Oliveira ◽  
L.G. Oliveira ◽  
J.F. Azevedo ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Melting Point ◽  
Laser Beam ◽  
316L Stainless Steel ◽  
Turbine Blades ◽  
Scanning Speed ◽  
Sample Surface ◽  
Laser Process

This study shows the influence of the temperature in the Direct Forming Laser process (DFL) of 316L stainless steel metal powder. Results shows that an increasing in the sample surface temperature can improve the laser beam absorption in the DFL process. A pre-heating in the substrate and in the powder contributed to decrease the time to reach the melting point and to improve the surface roughness. This effect was investigated with constant lasers parameters (scanning speed and intensity) and a heating in the samples in the temperature range of 20oto 200oC. It was possible to evaluate the DFL process and to optimize the quality of the sample surface roughness. These results will benefit the knowledge of the DFL technology that can be applied in the development of turbine blades.

Effect of binder composition on properties of 316L stainless steel bimodal powder feedstock

2019 ◽  
Author(s):  
Nikita Toropkov ◽  
Elena Glazkova ◽  
Nikolay Rodkevich ◽  
Aleksandr Pervikov ◽  
Marat Lerner
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Powder Feedstock ◽  
Binder Composition

scholarly journals Directed Energy Deposition of AISI 316L Stainless Steel Powder: Effect of Process Parameters

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 932
Author(s):  
Alberta Aversa ◽  
Giulio Marchese ◽  
Emilio Bassini
Keyword(s):  
Stainless Steel ◽  
Tensile Properties ◽  
Energy Deposition ◽  
316L Stainless Steel ◽  
Aisi 316L ◽  
Aisi 316L Stainless Steel ◽  
Directed Energy Deposition ◽  
Directed Energy ◽  
Building Parameters

During Laser Powder-Directed Energy Deposition (LP-DED), many complex phenomena occur. These phenomena, which are strictly related to the conditions used during the building process, can affect the quality of the parts in terms of microstructural features and mechanical behavior. This paper investigates the effect of building parameters on the microstructure and the tensile properties of AISI 316L stainless-steel samples produced via LP-DED. Firstly, the building parameters were selected starting from single scan tracks by studying their morphology and geometrical features. Next, 316L LP-DED bulk samples built with two sets of parameters were characterized in terms of porosity, geometrical accuracy, microstructure, and mechanical properties. The tensile tests data were analyzed using the Voce model and a correlation between the tensile properties and the dislocation free path was found. Overall, the data indicate that porosity should not be considered the unique indicator of the quality of an LP-DED part and that a mechanical characterization should also be performed.

Simulation on temperature fields and phase transformation of 316L stainless steel tubes during Orbital – TIG auto welding process

2021 ◽  
Vol 95 ◽  
pp. 2-10
Author(s):  
Manh Ngo Huu ◽  
Keyword(s):  
Numerical Simulation ◽  
Stainless Steel ◽  
Phase Transformation ◽  
316L Stainless Steel ◽  
Welding Process ◽  
Temperature Fields ◽  
Heat Distribution ◽  
Steel Tubes ◽  
Steel Pipes

Orbital - TIG (OT) auto welding process was applied for the weld connection of the fixed pipe lines. The heat distribution of the OT welding has influenced phase transformation and quality of the weld. In this paper, the temperature fields and phase transformation of 316L stainless steel pipes have been simulated during OT auto welding process. The numerical simulation has been used and supported by the JMATPRO 7.0 and SYSWELD softwares.

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