scholarly journals Effect of Post-Weld Heat Treatment on Microstructure and Hardness Evolution of Functionally Graded Materials Produced by Direct Energy Deposition

2021 ◽  
Vol 59 (2) ◽  
pp. 81-98
Author(s):  
Giseung Shin ◽  
Yongho Park ◽  
Dae Whan Kim ◽  
Ji hyun Yoon ◽  
Jeoung Han Kim
Keyword(s):  
Heat Treatment ◽  
Energy Deposition ◽  
Lath Martensite ◽  
Bainitic Ferrite ◽  
Post Weld Heat Treatment ◽  
Functionally Graded ◽  
Direct Energy Deposition ◽  
Type 316L ◽  
Direct Energy ◽  
Weld Heat

In this work, the effects of post weld heat treatment (PWHT) on the microstructure and mechanical properties of functionally gradient materials (FGM) was investigated. The FGM consisted of five different layers which were mixtures of austenitic stainless steel (type 316L) and ferritic steel (LAS). The ratio of type 316L and LAS powder in each deposition layer was 100:0, 75:25, 50:50, 25:75, and 0:100. FGM samples were successfully fabricated without cracks or delamination by a direct energy deposition process. The sensitization phenomenon of the FGM samples was investigated after PWHT. The PWHTs were conducted at 700<sup>o</sup>C, 900<sup>o</sup>C, and 1100<sup>o</sup>C for 4 hours and the samples were then air-cooled. After PWHT, the annealed specimens were observed by optical and scanning electron microscopy to analyze their microstructure. The occurrence of sensitization was found in the specimen annealed at 700<sup>o</sup>C. The contents of Cr and C increased substantially along grain boundaries. However, the sensitization did not occur in other samples annealed at 900<sup>o</sup>C and 1100<sup>o</sup>C. In the C and D layers of the 1100<sup>o</sup>C annealed sample, micro-hardness was measured to be very high due to the formation of bainitic ferrite and a lath martensite structure. In addition, a reduction of the austenite fraction was confirmed by Electron Back Scatter Diffraction.

scholarly journals A Study on the Influence of Laser Power on the Microstructure and Mechanical Properties of Functionally Graded Materials Produced by Direct Energy Deposition

2020 ◽  
Vol 58 (11) ◽  
pp. 782-792
Author(s):  
Giseung Shin ◽  
Ji hyun Yoon ◽  
Dae Whan Kim ◽  
Yongho Park ◽  
Jeoung Han Kim
Keyword(s):  
Mechanical Properties ◽  
Laser Power ◽  
Energy Deposition ◽  
Deposition Process ◽  
Functionally Graded ◽  
Direct Energy Deposition ◽  
Microstructure And Mechanical Properties ◽  
Type 316L ◽  
Direct Energy ◽  
Small Change

This study investigated the effects of laser power on the microstructure and mechanical properties of functionally gradient materials (FGM) produced by direct energy deposition. The FGM consisted of five different layers, which were a mixture of austenitic stainless steel (Type 316L) and ferritic steel (HSLA). During the direct energy deposition, two different laser power conditions (450W and 380W) were used. The ratio of Type 316L and HSAL at each deposition layers were 100:0, 65:35, 50:50, 25:75, and 0:100. After the direct energy deposition process, no cracks or delamination were seen between layers of the FGM. The effects of laser power on chemical composition and microstructure were not significant. However, as the laser power decreased, tensile strength and elongation changed with a small change in grain size.

scholarly journals Small Diameter Tube Post-Weld Heat Treatment Process with Brinell Hardness and Microstructure Inspection

2021 ◽  
Vol 2083 (2) ◽  
pp. 022009
Author(s):  
Xiangqian Qi
Keyword(s):  
Heat Treatment ◽  
Constant Temperature ◽  
Welded Joints ◽  
Brinell Hardness ◽  
Lath Martensite ◽  
Small Diameter ◽  
Hardness Test ◽  
Post Weld Heat Treatment ◽  
Microstructure Observation ◽  
Weld Heat

Abstract The local post-weld heat treatment (PWHT) process test of 9Cr-3W-3Co small-diameter pipe welded joints was carried out using rope-type resistance heaters with different parameters, and the Brinell hardness test and microstructure observation were carried out on the welded joints after heat treatment. The results show that when the heating width was 200mm, the constant temperature was 790°C-800°C, and the constant temperature time was 2 hours, the Brinell hardness of the weld was in the range of 246HBW-265HBW, which had good performance. After tempering at 760°C-800°C, the welds all showed a clear tempered lath martensite.

An Overview of Metallic Materials Fabrication by Direct Energy Deposition

2021 ◽  
Vol 882 ◽  
pp. 11-20
Author(s):  
P. Azhagarsamy ◽  
K. Sekar ◽  
K.P. Murali
Keyword(s):  
Stainless Steel ◽  
Nickel Alloys ◽  
Energy Deposition ◽  
Functionally Graded ◽  
Research Progress ◽  
Metallic Materials ◽  
Related Factors ◽  
Direct Energy Deposition ◽  
Advantages And Disadvantages ◽  
Direct Energy

Laser-based Direct Energy Deposition (L-DED) is a very quick and freeform fabrication process. L-DED is useful to fabricate near net shape for engineering applications as well as medical applications. L-DED has been successful in making a variety of pure metals and its alloys for industrial needs. This review paper gives an overview of the research progress in various types of metallic materials like nickel alloys, Stainless Steel (SS), and Functionally Graded Materials (FGMs) fabricated by L-DED. Simultaneously, the effects of process parametric related factors also discussed. Introduction about nickel alloys, Stainless Steel, and FGMs relevant findings, and their advantages and disadvantages for these alloys are communicated. The paper shows the metallurgical, mechanical properties, and post-processing effects on L-DED fabricated nickel alloys, SS, and FGMs. This paper will be helpful to the researchers and industrialists and for those who are interested to do research in this field.

scholarly journals Machining and heat treatment as post-processing strategies for Ni-superalloys structures fabricated using direct energy deposition

2021 ◽  
Vol 61 ◽  
pp. 236-244
Author(s):  
Francesco Careri ◽  
Stano Imbrogno ◽  
Domenico Umbrello ◽  
Moataz M. Attallah ◽  
José Outeiro ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Energy Deposition ◽  
Post Processing ◽  
Direct Energy Deposition ◽  
Processing Strategies ◽  
Direct Energy

scholarly journals Influence of Direct Energy Deposition Parameters on Ti–6Al–4V Component’s Structure-Property Homogeneity

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 887
Author(s):  
Chan Hyeok Lee ◽  
P. L. Narayana ◽  
Seong-Woo Choi ◽  
N. S. Reddy ◽  
Jae H. Kim ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Process Parameters ◽  
Energy Deposition ◽  
Mechanical Characteristics ◽  
Structure Property ◽  
Ann Model ◽  
Direct Energy Deposition ◽  
Specific Strength ◽  
Direct Energy ◽  
Artificial Neural Network Ann

Ti–6Al–4V alloy is a typical 3D printing metal, and its application has been expanded to various fields owing to its excellent characteristics such as high specific strength, high corrosion resistance, and biocompatibility. In particular, direct energy deposition (DED) has been actively explored in the fields of deposition and the repair of large titanium parts. However, owing to the complicated thermal history of the DED process, the microstructures of the fusion zone (FZ), heat-affected zone (HAZ), and base metal (BM) are different, which results in variations of their mechanical characteristics. Therefore, the process reliability needs to be optimized. In this study, the microstructure and hardness of each region were investigated with respect to various DED process parameters. An artificial neural network (ANN) model was used to correlate the measured characteristics of the FZ, HAZ, and BM of Ti–6Al–4V components with the process parameters. The variation in the mechanical characteristics between the FZ, HAZ, and BM was minimized through post-heat treatment. Heat treatment carried out at 950 °C for 1 h revealed that the microstructure and hardness values throughout the component were homogeneous.

scholarly journals Additive manufacturing of functionally graded Ti-Al structures by laser-based direct energy deposition

2021 ◽  
Vol 68 ◽  
pp. 1524-1534
Author(s):  
Hendrik Hotz ◽  
Marco Zimmermann ◽  
Sebastian Greco ◽  
Benjamin Kirsch ◽  
Jan C. Aurich
Keyword(s):  
Additive Manufacturing ◽  
Energy Deposition ◽  
Functionally Graded ◽  
Direct Energy Deposition ◽  
Direct Energy
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