Regionalization of microstructure and mechanical properties of Ti6Al4V transition area fabricated by WAAM-LMD hybrid additive manufacturing

Effect of Welding Speed on Microstructure and Anisotropic Properties of Wire-Arc Additive-Manufactured Ti-6Al-4V alloy

Investigation of Microstructures, Defects, and Mechanical Properties of Titanium-Zirconium-Molybdenum Alloy Manufactured by Wire Arc Additive Manufacturing

Titanium‑zirconium‑molybdenum (TZM), one of the refractory alloys, has extraordinary physicochemical properties, making it ideal for usage in extreme environmental applications (e.g., high-temperature and nuclear). Due to the scalability and near-net shape fabrication, metal additive manufacturing processes have several advantages, leading it to be the possible solution for the fabrication of refractory alloy structures. Wire arc additive manufacturing (WAAM) has several advantages, including high deposition rate, energy efficiency, and cost-effective manufacturing of large components. In this study, we comprehensively investigated the relationships among process, microstructures, mechanical properties, and defects of TZM thin-walls manufactured by WAAM using four heat input conditions: 180A, 200A, 220A, and 240A. The microstructures were investigated using multi-scale material characterization techniques. Columnar grains were generated along the build direction, and carbide precipitates were found uniformly distributed in the Mo matrix. Multi-scale pores and cracks were present in the microstructures. The average microhardness values for the deposits ranged from 188.5 to 193.5 hardness scales of Vickers. The highest yield strength, 195 MPa, was found in the 200A heat input condition. The primary fracture mode was identified as a brittle transgranular. The area fraction of porosity was calculated >1% in each condition, with the largest being 2.04% in the 240A deposit. 

Investigation of microstructures, defects, and mechanical properties of titanium-zirconium-molybdenum alloy manufactured by wire arc additive manufacturing

Abstract The condition of the consumables is a key factor determining the waste reduction in the welding processes and the quality of the welded joint. The paper presents the results of tests of four types of flux-cored wires dedicated for welding high-strength steels, stored for 1 month and 6 months in Poland in two urbanized areas: in a large seaside city (Gdańsk) and in Warsaw, located in the center of the country. The wires were subjected to macroscopic and microscopic (stereoscopic, SEM) observations, EDS analysis, technological tests assessing elastic properties and targetability. The degree of degradation of the wires was also tested using resistance measurements. In order to assess the effect of storing wires on the weldability of steel, the diffusible hydrogen content in deposited metal was determined by high-temperature extraction. It was found that the storage caused changes in the surface condition of the wires, affected their elasticity and electrical properties, which affects the behavior of the wires during welding. A significant influence of storage conditions on the hydrogenation of deposited metal was found: in the case of three types of wires, the level of low hydrogen processes was exceeded and the maximum result was 15.18 ml/100 g of deposited metal. It was also found that copper-plated wire showed a significantly increased resistance to storage conditions compared to non-copper-plated wires. 

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Storage of High-Strength Steel Flux-Cored Welding Wires in Urbanized Areas

Effect of heat input on microstructure and mechanical property of wire-arc additive manufactured Ti-6Al-4V alloy

Temperature Dependency of Hydrogen Embrittlement in Thermally H-precharged STS 304 Austenitic Stainless Steel

Among various processes for manufacturing complex-shaped metal parts, additive manufacturing is highlighted as a process capable of reducing the wastage of materials without requiring a post-process, such as machining and finishing. In particular, it is a suitable new manufacturing technology for producing AISI H13 tool steel for hot-worked molds with complex cooling channels. In this study, we manufactured AISI H13 tool steel using the laser power bed fusion (LPBF) process and investigated the effects of tempering temperature and holding time on its microstructure and mechanical properties. The mechanical properties of the sub-grain cell microstructure of the AISI H13 tool steel manufactured using the LPBF process were superior to that of the H13 tool steel manufactured using the conventional method. These sub-grain cells decomposed and disappeared during the austenitizing process; however, the mechanical properties could be restored at a tempering temperature of 500 °C or higher owing to the secondary hardening and distribution of carbides. Furthermore, the mechanical properties deteriorated because of the decomposition of the martensite phase and the accumulation and coarsening of carbides when over-tempering occurred at 500 °C for 5 h and 550 °C for 3 h.

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Influence of Tempering Temperature and Time on Microstructure and Mechanical Properties of Additively Manufactured H13 Tool Steel

Effect of Ti/N Ratio on Grain Growth Inhibition in the Coarse-Grained Heat-Affected Zone of Low Carbon Steels Simulated for Ultra-High Heat Input and Tandem Electro-Gas Welding

Prediction on cold crack sensitivity using hydrogen embrittlement index measured from in situ slow-strain-rate testing for multipass flux-cored arc weld metals of shipbuilding and offshore steels

Junghoon Lee

Papers

Effect of heat input on microstructure and mechanical property of wire-arc additive manufactured Ti-6Al-4V alloy

Temperature Dependency of Hydrogen Embrittlement in Thermally H-precharged STS 304 Austenitic Stainless Steel

Influence of Tempering Temperature and Time on Microstructure and Mechanical Properties of Additively Manufactured H13 Tool Steel

Effect of Ti/N Ratio on Grain Growth Inhibition in the Coarse-Grained Heat-Affected Zone of Low Carbon Steels Simulated for Ultra-High Heat Input and Tandem Electro-Gas Welding

Prediction on cold crack sensitivity using hydrogen embrittlement index measured from in situ slow-strain-rate testing for multipass flux-cored arc weld metals of shipbuilding and offshore steels