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Dr. Bernd Wolter

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Guest Editor

Fraunhofer Institute for Nondestructive Testing IZFP, 66123 Saarbrücken, Germany
Interests: process monitoring and control; nondestructive evaluation (NDE); steels; material characterization; artificial intelligence

Dr. Benjamin Strass

E-Mail Website
Guest Editor

Fraunhofer Institute for Non-Destructive Testing IZFP, 66123 Saarbrücken, Germany
Interests: non-destructive testing (NDT); process monitoring; joining; welding; microstructure; mechanical properties

Special Issue Information

Dear Colleagues,

Welding alloys and steels are widely used in a variety of industries and applications. The microstructure and mechanical properties of these materials are affected by the properties of the base material and the welding process itself. During welding, a material’s microstructure can be changed, which can have implications for the mechanical properties of the welded joint. For example, high-carbon steels are more prone to forming martensite, which can lead to reduced toughness. Nickel-based alloys are often used in high-temperature applications. However, they can be difficult to weld due to their high melting points and tendency to form brittle microstructures if not welded properly. These examples show that understanding the microstructure and mechanical properties of welding alloys and steels is crucial in producing high-quality welds. Overall, this is a broad and diverse field with many important research topics, such as welding process optimization, materials selection, material characterization, mechanical testing, weld defect analysis, as well as corrosion and wear resistance. Contributions to this Special Issue should address new findings in these research topics. The editors would especially appreciate papers that reference the application of nondestructive evaluation (NDE) and of artificial intelligence (AI) in welding.

Dr. Bernd Wolter
Dr. Benjamin Strass
Guest Editors

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Keywords

alloys (welding)
artificial intelligence
steels
microstructure
mechanical properties

Published Papers (2 papers)

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Research

13 pages, 5300 KiB

Open AccessArticle

Effect of Mg Addition on Inclusions in the Welding Heat-Affected Zone of Pressure Vessel Steels

by Yan Liu, Wenguang Zhang, Kai Wang and Anna Du

Materials 2023, 16(23), 7369; https://doi.org/10.3390/ma16237369 - 27 Nov 2023

Cited by 1 | Viewed by 611

Abstract

With the development of the pressure vessel industry, high-energy wire welding has a great future. However, this means higher demands on the weldability of pressure vessel steels. Controlling inclusions via oxidative metallurgy is a reliable method of improving the weldability of pressure vessel steels. Hence, in this paper, experimental steels with different Mg element mass fractions were prepared using vacuum metallurgy. Simulated welding for high-heat input welding was carried out using the Gleeble-2000 welding thermal simulation test machine. The inclusions in the welding heat-affected zone (HAZ) in the experimental steels were observed using an optical microscope (OM) and scanning electron microscope (SEM). The compositions of the inclusions were analyzed using an energy-dispersive spectrometer (EDS). The research results indicated that the addition of Mg could increase the number density of the inclusions in the welding HAZ. With the addition of Mg from 0 to 5 wt.%, the total number density of the inclusions increased from 133 to 687 pieces/mm^2, and the number density of the inclusions with a size of 0–5 μm² increased from 122 to 579 pieces/mm². The inclusions in the experimental steel welding HAZ with Mg elements were mainly elliptical composite inclusions composed of (Mg-Zr-O) + MnS. Moreover, MnS precipitated on the surface of the Mg-containing inclusions in the welding HAZ. Intragranular acicular ferrite (IAF) nucleation was primarily induced via the minimum lattice mismatch mechanism, supplemented with stress-strain energy and inert interface energy mechanisms. Full article

(This article belongs to the Special Issue Study on the Microstructure and Mechanical Properties of Welding Alloys and Steels)

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24 pages, 21637 KiB

Open AccessArticle

Microstructure, Texture, and Mechanical Properties of Friction Stir Spot-Welded AA5052-H32: Influence of Tool Rotation Rate

by Mohamed M. Z. Ahmed, Mohamed M. El-Sayed Seleman, Ibrahim Albaijan and Ali Abd El-Aty

Materials 2023, 16(9), 3423; https://doi.org/10.3390/ma16093423 - 27 Apr 2023

Cited by 3 | Viewed by 1249

Abstract

Friction stir spot welding (FSSW) of similar AA5052-H32 joints has numerous benefits in shipbuilding, aerospace, and automotive structural applications. In addition, studying the role of tool rotation speed on the microstructure features, achieved textures, and joint performance of the friction stir spot-welded (FSSWed) joint still needs more systematic research. Different FSSWed AA5052-H32 lap joints of 4 mm thickness were produced at different heat inputs using three tool rotation speeds of 1500, 1000, and 500 rpm at a constant dwell time of 2 s. The applied thermal heat inputs for achieving the FSSW processes were calculated. The produced joints were characterized by their appearance, macrostructures, microstructures, and mechanical properties (hardness contour maps and maximum tensile–shear load) at room temperature. The grain structure and texture developed for all the FSSWed joints were deeply investigated using an advanced electron backscattering diffraction (EBSD) technique and compared with the base material (BM). The main results showed that the average hardness value of the stir zone (SZ) in the welded joints is higher than that in the AA5052-H32 BM for all applied rotation speeds, and it decreases as the rotation speed increases from 500 to 1000 rpm. This SZ enhancement in hardness compared to the BM cold-rolled grain structure is caused by the high grain refining due to the dynamic recrystallization associated with the FSSW. The average grain size values of the stir zones are 11, 9, and 4 µm for the FSSWed joints processed at 1500, 1000, and 500 rpm, respectively, while the BM average grain size is 40 µm. The simple shear texture with B/-B components mainly dominates the texture. Compared to the welded joints, the joint processed at 500 rpm and a 2 s duration time attains the highest tensile-shear load value of 4330 N. This value decreases with increasing rotation speed to reach 2569 N at a rotation speed of 1500. After tensile testing of the FSSWed joints, the fracture surface was also examined and discussed. Full article

(This article belongs to the Special Issue Study on the Microstructure and Mechanical Properties of Welding Alloys and Steels)

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