Powdered Metal Heat Treatment Apparatus Designed for a Laboratory

2020 ◽  
Author(s):  
Jacob Porter ◽  
John Parmigiani
Keyword(s):  
Heat Treatment ◽  
Additive Manufacturing ◽  
Material Properties ◽  
Powder Flow ◽  
Manufacturing Processes ◽  
Metal Production ◽  
Handling System ◽  
Powdered Metal ◽  
Flow Through ◽  
Metal Additive

Abstract Metal additive manufacturing is a rapidly growing and sophisticated industry however the manufacturing processes and equipment for the heat treatment of the needed powdered metals is underdeveloped. Heat treatment is a key step in the powdered metal production process and is often needed to produce desired material properties. The objective of this paper is to examine the design of a heat treatment machine that addresses the needs of a laboratory performing research on powdered metals. The device was designed to address the three criteria of a heat treatment device; treatment, environment, and containment. The treatment criterion is accomplished by continuous powder flow through a furnace. The environment criterion is accomplished through a gas handling system capable of creating both an argon and vacuum environment. Finally, the containment criterion is accomplished through a network of tubes that provides structure to contain the powder. The design of this machine will allow research and development labs to heat treat powdered to a higher quality at a significantly faster rate.

scholarly journals Feasibility Study on Additive Manufacturing of Ferritic Steels to Meet Mechanical Properties of Safety Relevant Forged Parts

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 383
Author(s):  
Linda Mally ◽  
Martin Werz ◽  
Stefan Weihe
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Tensile Strength ◽  
Additive Manufacturing ◽  
Size Distribution ◽  
Material Properties ◽  
Ferritic Steels ◽  
Manufacturing Processes ◽  
Nuclear Facilities ◽  
Hardness Values

Additive manufacturing processes such as selective laser melting are rapidly gaining a foothold in safety-relevant areas of application such as powerplants or nuclear facilities. Special requirements apply to these applications. A certain material behavior must be guaranteed and the material must be approved for these applications. One of the biggest challenges here is the transfer of these already approved materials from conventional manufacturing processes to additive manufacturing. Ferritic steels that have been processed conventionally by forging, welding, casting, and bending are widely used in safety-relevant applications such as reactor pressure vessels, steam generators, valves, and piping. However, the use of ferritic steels for AM has been relatively little explored. In search of new materials for the SLM process, it is assumed that materials with good weldability are also additively processible. Therefore, the processability with SLM, the process behavior, and the achievable material properties of the weldable ferritic material 22NiMoCr3-7, which is currently used in nuclear facilities, are investigated. The material properties achieved in the SLM are compared with the conventionally forged material as it is used in state-of-the-art pressure water reactors. This study shows that the ferritic-bainitic steel 22NiMoCr3-7 is suitable for processing with SLM. Suitable process parameters were found with which density values > 99% were achieved. For the comparison of the two materials in this study, the microstructure, hardness values, and tensile strength were compared. By means of a specially adapted heat treatment method, the material properties of the printed material could be approximated to those of the original block material. In particular, the cooling medium/cooling method was adapted and the cooling rate reduced. The targeted ferritic-bainitic microstructure was achieved by this heat treatment. The main difference found between the two materials relates to the grain sizes present. For the forged material, the grain size distribution varies between very fine and slightly coarse grains. The grain size distribution in the printed material is more uniform and the grains are smaller overall. In general, it was difficult and only minimal possible to induce grain growth. As a result, the hardness values of the printed material are also slightly higher. The tensile strength could be approximated to that of the reference material up to 60 MPa. The approximation of the mechanical-technological properties is therefore deemed to be adequate.

Effect of Time Spacing and Hatch Spacing on Thermal Material Properties and Melt Pool Geometry in Additive Manufacturing of S316L

2019 ◽  
Author(s):  
Elham Mirkoohi ◽  
Daniel E. Sievers ◽  
Steven Y. Liang
Keyword(s):  
Heat Transfer ◽  
Additive Manufacturing ◽  
Material Properties ◽  
Metal Additive Manufacturing ◽  
Melt Pool ◽  
Experimental Values ◽  
Melt Pool Size ◽  
Transfer Mechanisms ◽  
Hatch Spacing ◽  
Metal Additive

Abstract A physics-based analytical solution is proposed in order to investigate the effect of hatch spacing and time spacing (which is the time delay between two consecutive irradiations) on thermal material properties and melt pool geometry in metal additive manufacturing processes. A three-dimensional moving point heat source approach is used in order to predict the thermal behavior of the material in additive manufacturing process. The thermal material properties are considered to be temperature dependent since the existence of the steep temperature gradient has a substantial influence on the magnitude of the thermal conductivity and specific heat, and as a result, it has an influence on the heat transfer mechanisms. Moreover, the melting/solidification phase change is considered using the modified heat capacity since it has an influence on melt pool geometry. The proposed analytical model also considers the multi-layer aspect of metal additive manufacturing since the thermal interaction of the successive layers has an influence on heat transfer mechanisms. Temperature modeling in metal additive manufacturing is one of the most important predictions since the presence of the temperature gradient inside the build part affect the melt pool size and geometry, thermal stress, residual stress, and part distortion. In this paper, the effect of time spacing and hatch spacing on thermal material properties and melt pool geometry is investigated. Both factors are found statistically significant with regard to their influence on thermal material properties and melt pool geometry. The predicted melt pool size is compared to experimental values from independent reports. Good agreement is achieved between the proposed physics-based analytical model and experimental values.

scholarly journals Analytical Thermal Modeling of Powder Bed Metal Additive Manufacturing Considering Powder Size Variation and Packing

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1988 ◽  
Author(s):  
Jinqiang Ning ◽  
Wenjia Wang ◽  
Xuan Ning ◽  
Daniel E. Sievers ◽  
Hamid Garmestani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Additive Manufacturing ◽  
Heat Loss ◽  
Powder Material ◽  
Material Properties ◽  
Powder Size ◽  
Temperature Prediction ◽  
Powder Bed ◽  
Metal Additive Manufacturing ◽  
Metal Additive

This work presents a computationally efficient predictive model based on solid heat transfer for temperature profiles in powder bed metal additive manufacturing (PBMAM) considering the heat transfer boundary condition and powder material properties. A point moving heat source model is used for the three-dimensional temperature prediction in an absolute coordinate. The heat loss from convection and radiation is calculated using a heat sink solution with a mathematically discretized boundary considering non-uniform temperatures and heat loss at the boundary. Powder material properties are calculated considering powder size statistical distribution and powder packing. The spatially uniform and temperature-independent material properties are employed in the temperature prediction. The presented model was tested in PBMAM of AlSi10Mg under different process conditions. The calculations of material properties are needed for AlSi10Mg because of the significant difference in thermal conductivity between powder form and solid bulk form. Close agreement is observed upon experimental validation on the molten pool dimensions.

scholarly journals Assumption of Constraining Force to Explain Distortion in Laser Additive Manufacturing

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2327 ◽  
Author(s):  
Deqiao Xie ◽  
Jianfeng Zhao ◽  
Huixin Liang ◽  
Zongjun Tian ◽  
Lida Shen ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Contributory Factor ◽  
Sectional Area ◽  
Laser Additive Manufacturing ◽  
Element Analysis ◽  
Cross Sectional ◽  
Fea Model ◽  
Metal Additive ◽  
Distortion Mechanism

Distortion is a common but unrevealed problem in metal additive manufacturing, due to the rapid melting in metallurgy and the intricate thermal-mechanical processes involved. We explain the distortion mechanism and major influencing factors by assumption of constraining force, which is assumed between the added layer and substrate. The constraining force was set to act on the substrate in a static structural finite element analysis (FEA) model. The results were compared with those of a thermal-mechanical FEA model and experiments. The constraining force and the associated static structural FEA showed trends in distortion and stress distribution similar to those shown by thermal-mechanical FEA and experiments. It can be concluded that the constraining force acting on the substrate is a major contributory factor towards the distortion mechanism. The constraining force seems to be primarily related to the material properties, temperature, and cross-sectional area of the added layer.

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