Mixing Design for ATIG Morphology and Microstructure Study of 316L Stainless Steel

Abstract

This work is a study of the effects of oxides combination on the morphology of 316L stainless steel welds. A series of thirteen weld lines were carried out using thirteen different oxides. Based on the depth and ratio D/W results, three candidate oxides were selected: Ti2O, Mn2O3, and SiO2. Mixing method available in Minitab 17 software is the most appropriate method to find the optimal combinations to get the best depth and D/W ratio. According to simplex lattice degree four, nineteen combinations of these oxides were prepared. The results show that the optimal composition of flux was: 66%SiO2-34% Mn2O3. The depth and D/W ratio increased to 8.85mm and 0.98 respectively for optimal ATIG, whereas for the conventional TIG welding, the depth and the ratio D/W didn't exceed 1.65mm and 0.17 respectively. For TIG weld joint the hardness is about 47 HRA and it increases to 77 HRA for the optimal ATIG weld joint. The absorbed energies in Charpy impact test are 146 and 138kJ in the weld zone and in the heat affected zone respectively for the TIG welding and they dropped to 111 and 74kJ for the optimal ATIG welding. The fracture surface examined by scanning electron microscope (SEM) shows a ductile fracture for TIG weld with small dimples but ductile-brittle fracture for ATIG weld. Energy dispersive spectroscopy (EDS/SEM) analysis shows the formation of FeS2 and SiO2 in the weld zone causing low absorbed energy for ATIG weld.

Fe2O3 Nanowire Flux Enabling Tungsten Inert Gas Welding of High-Manganese Steel Thick Plates with Improved Mechanical Properties

“…Based on the study, for nanowire flux, the dT/dx value is higher than that of microscale flux. This could be attributed to the size effect of melting point [36,49]. Due to the surface and quantum confinement effects of nanomaterials [50], there are fewer "neighbors" around the atoms at the surface than a microparticle, result in a lower binding energy per atom.…”

“…Among those kinds of oxides, although nearly all of them increase the penetration of the welding, the effects of their addition on the penetration are quite different. When the target steel plate is ferritic, the increase in weld penetration and the decrease in bead width are significant with the use of the activating fluxes Fe 2 O 3 , ZnO, MnO 2 and CrO 3 [34,35]; when welding austenitic steel, the results of adding SiO 2 , Fe 2 O 3 and TiO 2 as fluxes are more obvious [36,37]. Recently, various innovations in traditional welding and joining were reported by integrating nanotechnology [38,39].…”

A Comparative Study of the Oxidation Behavior of Hot-Rolled Steel established from Medium and Thin Slabs oxidized in 20% H2O-N2 at 600-900°C

“…Hematite (Fe 2 O 3 ), magnetite (Fe 3 O 4 ), and wustite (FeO) are the major layers found in the oxide scales that form on the steel surface [3][4][5][6][7][8]. The morphologies of the oxide scales differ according to the alloying elements [9][10][11][12][13][14] and oxidizing atmosphere [15][16][17][18][19]. Stainless steel or alloy steel models have been used in many studies, but there are a limited number of studies regarding hotrolled steel [20][21][22][23][24][25].…”

Comparative Microstructural, Mechanical and Corrosion Study between Dissimilar ATIG and Conventional TIG Weldments of 316L Stainless Steel and Mild Steel

“…Compared to TIG, ATIG has many advantages [7,8]. Among the latter, the activating flux of ATIG eliminates the need for edge preparation, increases the penetration depth, reduces the number of weld passes, and reduces distortion, meaning heat-to-heat variations in the base metal compositions can be avoided [9][10][11]. Hence, two main mechanisms have been proposed to increase the weld penetration.…”