Hydrogen trapping and desorption affected by ferrite grain boundary types in shielded metal and flux-cored arc weldments with Ni addition

Tungsten Inert Gas (TIG) welding is a commonly used welding technique for ferritic stainless steel, due to its ability to produce high-quality, clean, and precise welds. This welding method provides excellent control over the heat input, making it suitable for thin-walled, high-alloy materials such as ferritic stainless steel. The purpose of this study was to investigate the effect of using two different filler materials, 310 (austenitic) and 410 (ferritic), on the microstructural and mechanical properties of Tungsten Inert Gas (TIG) weld butt joints of 430 ferritic stainless steel (FSS). The results showed that the choice of filler material significantly impacted the dilution percentage, the chromium-nickel equivalent ratio, microstructure, microhardness, and tensile characteristics of the welded joint. The use of 310 filler resulted in a columnar microstructure, whereas the use of 410 filler resulted in a ferritic (acicular ferrite) microstructure with the presence of martensite and austenite. The sample welded with 410 filler demonstrated superior mechanical properties compared to the sample welded with 310 filler. These findings emphasize the importance of selecting the appropriate filler material in order to achieve the desired microstructural and mechanical properties in 430 FSS welded joints.

Section: Resultsmentioning

confidence: 99%

Influence of Filler Material on the Microstructural and Mechanical Properties of 430 Ferritic Stainless Steel Weld Joints

Shanmugasundar¹,

Bansod

Schindlerová

et al. 2023

“…al. proposed the high HAGB density results in a lower H diffusion coefficient and higher density of relatively strong HAGB traps [ 24 ]. Di et al suggested that increasing the proportion of HAGB can significantly increase the strength and toughness of the material at the same time [ 25 ].…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, the conventional welding heat inputted CGHAZ did not experience evident blunting and plastic deformation during the propagation of the prefabricated fatigue crack, and the crack propagated along the path with the lowest energy consumption after loading, which was consistent with the SEM result ( Figure 4 and Figure 5 ). Coarse lath bainite without plastic deformation and a large number of LAGBs inside the grains cannot effectively prevent crack propagation [ 24 ].…”

Section: Resultsmentioning

confidence: 99%

Comparison of Fracture Toughness in the Coarse-Grain Heat-Affected Zone of X80 Pipelines Girth-Welded under Conventional and Ultra-Low Heat Input

Liu

et al. 2022

The coarse-grain heat-affected zones (CGHAZs) of X80 girth-welded steel pipelines are prone to embrittlement, which has an extremely adverse effect on their structural integrity. In the present work, the fracture behavior of the CGHAZs of X80 girth welds under the conditions of conventional and ultra-low heat input was studied. The fracture toughness of CGHAZs was evaluated using the crack tip opening displacement (CTOD) test at −10 °C, and the fracture behavior mechanism of CGHAZs were clarified by analyzing microstructural characteristics at prefabricated fatigue cracks containing fracture cloud image, scanning electron microscopy (SEM), and electron back-scatter diffraction (EBSD) figures. The results illustrate that the average fracture toughness (CTOD) value of the ultra-low heat input CGHAZ is 0.6 mm, and the dispersion of CTOD values is small, while the CTOD value of conventional heat input is only 0.04 mm. The ultra-low heat input makes the high-temperature residence time of the coarse-grained region short, reduces the proportion of prior austenite grain boundaries, and inhibits the formation of strip-like bainite and island-like M-A components. The reduction of these deleterious ductile microstructures increases the plastic reserve and deformation capacity of the CGHAZ.

“…The melt pools re-solidify to form a hardened layer [ 30 ]. M. Moshtaghi’s study [ 31 ] shows that different heat input and cooling rates lead to the formation of different microstructures of the material surface. More small-angle grain boundaries are formed during re-solidification, the re-solidified layer has a greater dislocation density.…”

Section: Discussionmentioning

confidence: 99%

Welding Defect and Mechanical Properties of Nanosecond Laser Cleaning 6005A Aluminum Alloy

Zhang

Long

et al. 2022

Nanosecond laser cleaning effectively removes oxide film and dirt from the surface of aluminum body parts for rail transit, as well as improving surface properties. The effect of laser cleaning on the quality of weld was studied in detail for different scanning frequencies and cleaning speeds. The effect of post-weld laser cleaning on weld quality was investigated. After laser cleaning at different parameters, the surface oxygen content was decreased and the surface roughness and surface hardness were increased. Variation of surface oxygen content was related to energy density and spot density. The lowest oxygen content was obtained at 150 W, 100 Hz and 0.8 m/min. Laser-generated craters changed surface morphology and improved surface roughness. The mechanical properties of the welded joints were slightly improved, which relates to a decrease in porosity. The minimum porosity of the laser-cleaned weld was 0.021%. This work provides new ideas for the nanosecond laser cleaning of aluminum alloy and its welding properties.