In this article, the mechanical properties and microstructure of 304L austenitic stainless steel/Incoloy 800HT nickel alloy dissimilar welded joints are investigated. The joints were made of 21.3 mm × 7.47 mm tubes using the TIG process with the use of S Ni 6082 nickel filler metal. No welding imperfections were found and high strength properties of joints were obtained, meeting the assumed acceptance criteria of the product’s standards. The tensile strength of the welded joints was higher than for the joined materials (Incoloy 800HT). Macro- and microscopic metallographic tests revealed the correct morphology of the joints and the appropriate structures in their critical zones. However, differences were found in the morphologies of the zones between the weld and the base materials. In fusion boundary from the side of the Incoloy 800HT alloy, no clear outline of the fusion line was observed (type A fusion boundary), while increased grain size and an epitaxial structure were observed. In turn, in the zone: weld–304L steel, a distinct fusion line was observed with areas with an increased amount of high-temperature δ ferrite (type B fusion boundary). No precipitates were found that could reduce the resistance of the joints to intergranular corrosion. A hardness decrease (approximately 30 HV0.1) in the transition zone: austenitic steel–weld and an increase of hardness (approximately 10 HV0.1) on the opposite side of the welded joint were observed.

Mechanical and Microstructural Characterization of TIG Welded Dissimilar Joints between 304L Austenitic Stainless Steel and Incoloy 800HT Nickel Alloy

Abstract This paper studies the phase composition, microstructure, hardness and wear resistance of nickel-base plasma sprayed coatings, on two types of substrates, steel and cast iron. The processing method of metal and compound powders for plasma spraying is detailed, together with the characteristics of the powders before and after processing. It has been found that in as-coated condition, the surface layers have phase composition of crystalline γ-Ni solid solution and amorphous phases on steel substrate. On cast iron substrate, in addition to these, Ni3B, CrB, Cr23C6 have been identified. The effect of heat treatment of coatings on steel substrate at temperatures up to 1200 °C has been investigated. It has been found that the coatings have high values of hardness and wear resistance. There are changes in the phase compositions on the surface of the Ni-base coatings during wear testing upon the effect of friction heat, and the wear volume after 60 min for the coating on cast iron substrate is much lower than for those on steel substrate.

Nickel-base plasma sprayed coatings on steel and cast iron substrates

Additive manufacturing (AM) is an expeditiously developing technology for the manufacturing of biomedical implants. It provides an excellent and broad opportunity for the bio-mimicry of desired complex profiles of bodily implants because of its customized fabrication, lower manufacturing time and cost. Metal AM of biomedical implants has increased many medical practitioner’s attention because of its increased fatigue strength and excellent corrosion resistance properties, patient-specific implants for a speedy recovery, and it is found to be a suitable alternative to amputation. But there are some issues related to metal AM that are desired dimensional accuracy, preferred surface quality, strength, etc. Based on the said shortcomings, the following properties are chosen for the present review article; mechanical and metallurgical behavior. The main objective is to review the above-stated properties for 3D printed biomedical implants manufactured through laser additive manufacturing (LAM), friction stir additive manufacturing (FS-AM), paste extruding deposition (PED) and selective laser melting (SLM) techniques and its future scope of AM processes.

Development of Biomedical Implants through Additive Manufacturing: A Review

Dissimilar friction stir welding of AA2198 and AA7475: Effect of solution treatment and aging on the microstructure and mechanical strength

This study investigated the microstructure of the dissimilar metal welding of Inconel 625 and AISI 316L using Continuous Current Gas Tungsten Arc Welding (CCGTAW) and Pulsed Current Gas Tungsten Arc Welding (PCGTAW) processes with ERNiCr-3, TIG 316L and twisted (ERNiCr-3 and TIG 316L) fillers. Microstructure examinations were carried out using an optical microscope and Scanning Electron Microscopy (SEM)/Energy Dispersive X-Ray (EDAX). The results of the study showed the existence of a partially melted zone (PMZ) on the AISI 316L side. Weld zone (WZ) analysis showed the existence of a multi-directional grain growth on the 316L side in all specimens, although less growth was found on the Inconel 625 side. Grain growth almost disappeared using PCGTAW with twisted fillers. SEM/EDAX investigations indicated that secondary deleterious secondary phases were tiny and white in five experiments. However, a meager amount of precipitates occurred in PCGTA welding with twisted fillers. Moreover, these were particularly innocent precipitates, represented by black dots in images, whereas other tiny white secondary phases are known to be brittle. As a result, PCGTA welding with twisted fillers exhibited the best metallurgical properties.

https://www.mdpi.com/2075-4701/8/10/797/pdf

Microstructural and Mechanical Characterization of Dissimilar Metal Welding of Inconel 625 and AISI 316L

This article investigated the weldability, metallurgical and mechanical properties of Inconel 625 and AISI 316L stainless steel weldments obtained by continuous current (CC) and pulsed current (PC) gas tungsten arc welding (GTAW) processes employing ERNiCr-3 and ER2209 fillers Microstructure studies showed the migrated grain boundaries at the weld zone of ERNiCr-3 weldments and multi-directional grain growth for ER2209 weldments It was inferred from the tension tests that the fracture occurred at the parent metal of AISI 316L in all the cases Charpy V-notch impact tests accentuated that the CCGTA weldments employing ERNiCr-3 filler offered better impact toughness of 77 J at room temperature Further a detailed study has been carried out to analyze the structure — property relationships of these weldments using the combined techniques of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis

Characterization of metallurgical and mechanical properties on the multi-pass welding of Inconel 625 and AISI 316L

Hastelloy X develops hot fissuring during fusion welding, which could be precluded using single-pulsed gas metal arc welding (SP-GMAW) and double-pulsed gas metal arc welding (DP-GMAW). The outcome of this research is to provide a better insight into microstructural characteristics, and mechanical properties of Hastelloy X welded by GMAW, SP-GMAW, and DP-GMAW techniques. GMAW depicts the cellular dendrites, whereas DP-GMAW and SP-GMAW displayed fine equiaxed dendrites. Mo-rich segregation is identified in the interdendritic region of GMAW owing to high solidification time. Mo-rich segregation is reduced for SP-GMAW, whereas it is completely precluded for DP-GMAW due to the existence of refined grain. The development of M3C (Fe2MoC) and M6C (Fe2Mo4C) carbide precipitates is identified in GMAW and SP-GMAW. But, DP-GMAW displays the absence of Mo-rich carbides and the development of Mo1Ni4 intermetallic precipitates. DP-GMAW provides better joint efficiency (96.32%), UTS, and ductility, which is followed by SP-GMAW and GMAW. DP-GMAW shows higher mean microhardness (7.31% and 3.52%) and impact toughness (49.01% and 26.67%) on comparison with GMAW and SP-GMAW, respectively. Inverse pole figure (IPF) maps of SP-GMAW weldment confirmed that the broad and straight dendrites formed tend to grow along direction during the entire solidification process. DP-GMAW also displays the major intensity shift from to direction. Evidence for the formation of equiaxed grains of random orientation along with dendrites is confirmed by IPF maps from DP-GMAW weldments. The presence of these equiaxed grains in the DP-GMAW weldment might have contributed to the enhancement of tensile properties.

Investigation of Double-Pulsed Gas Metal Arc Welding Technique to Preclude Carbide Precipitates in Aerospace Grade Hastelloy X

Friction based joining process for high strength aerospace aluminium alloy

https://robots.iopscience.iop.org/article/10.1088/1757-899X/402/1/012075/pdf

K. Gokul Kumar

Papers

Characterization of metallurgical and mechanical properties on the multi-pass welding of Inconel 625 and AISI 316L

Investigation of Double-Pulsed Gas Metal Arc Welding Technique to Preclude Carbide Precipitates in Aerospace Grade Hastelloy X

Friction based joining process for high strength aerospace aluminium alloy

Investigation on microstructure and tensile properties of dissimilar weld joints between AISI 316l and duplex 2205 stainless steel

Investigations on the Microstructure, Microsegregation and Hardness Properties of Bead on Plasma Arc Welded C-276 Alloy