Processing 304L stainless steel welding wire via electrochemical cold drawing

Corrosion of laser-welded stainless steel orthodontic wires

Galvanized steel sheets are widely-used in the construction and automobile industries to provide structural members with high corrosion resistance. When galvanized sheets are welded, zinc near a weld molten pool evaporates. As a result, the corrosion resistance is deteriorated and repair coating treatment is required after welding. The use of austenitic stainless steel welding materials with suitable ductility and high corrosion resistance appears to be beneficial. However, the conventional welding materials have such problems that zinc liquation cracking is likely to occur in the weld metal, a lot of welding spatter is generated and solidified slag is difficult to remove from the weld bead. To solve these problems, an austenitic stainless steel flux-cored wire was developed. Susceptibility to zinc liquation cracking was improved by increasing the ferrite content in the weld metal through the adjustment of Ni and Cr contents. The problems of the removal of solidified slag and the generation of welding spatter were solved by reducing the TiO2 content in flux to a level lower than that for a commercial wire. Thus, the weld appearance was improved, making repair coating treatment after welding unnecessary. The joints welded by the newly-developed welding material exhibited suitable mechanical properties and satisfactory corrosion resistance evaluated by salt spray testing.

During fusion welding of stainless steels and other high-Cr alloys, evaporation and oxidation of Cr from the molten weld pool result in the generation of carcinogenic hexavalent chromium (Cr[VI]) in the welding fume. Stringent new exposure limits from the Occupational Safety and Health Administration (OSHA) might limit the environment in which the welding of stainless steel will be possible in the future. Therefore, a Cr-free filler metal is needed to reduce the release of Cr(VI) during the welding of stainless steel. From the galvanic series, the corrosion potential of the Ni-Cu alloy K400 (UNS N04400) is located in the same potential range as Type 304 (UNS S30400) and Type 316 (UNS S31600) stainless steels. In this study, the applicability of the Monel-type filler metals for the welding of austenitic stainless steel is examined. Type 304L (UNS S30403) stainless steel plate was successfully welded with Monel filler wire, resulting in high-quality welds with no cracks. The welds survived long-term exposure to mildly aggressive environments like 0.1 M sodium chloride (NaCl) with no evidence of corrosion. However, Cu-rich regions in the weld were the weak spots for corrosion susceptibility.

Dislocation structure evolution in 304L stainless steel and weld joint during cyclic plastic deformation

This study aimed to evaluate and compare the bond strengths of four different lingual retainers and assess the adhesive remnant index (ARI) to determine their effectiveness in orthodontic retention. Eighty human incisor teeth were divided into four groups, with each group bonded using a different retainer: Group 1 (E-Glass retainer), Group 2 (0.017" Co-axial stainless steel wire), Group 3 (Splint C.T. fiber mesh), and Group 4 (0.010" stainless steel ligature wire). Bond strength was measured using a universal testing machine, and ARI scores were recorded to assess bond failure types. Group 1 (E-Glass retainer) demonstrated the highest bond strength, followed by Group 3 (Splint C.T. fiber mesh), Group 2 (Co-axial stainless steel wire), and Group 4 (stainless steel ligature wire). Cohesive bond failures were observed in most groups, except for the co-axial stainless steel wire group, which exhibited adhesive failures. E-Glass fiber-reinforced retainers showed the highest bond strength, making them a promising alternative to conventional stainless steel wires for orthodontic retention, especially in patients with esthetic concerns or nickel hypersensitivity. Stainless steel retainer groups exhibited lower bond strengths, and cohesive bond failures were prevalent. Further research is needed to validate these findings in clinical settings and evaluate the long-term effectiveness of different lingual retainers.

In order to fabricate fabrics with electromagnetic shielding effectiveness (EMSE) and other function, we fabricated Crisscross-section polyester /antibacterial nylon / stainless steel wires (CSP/AN/SSW) composite yarns with stainless wires as core yarn, antibacterial nylon and crisscross-section polyester as inner and out wrapped yarns, respectively. Knitted fabrics were fabricated with the metal composite yarns with wrap amount of 8 turns/cm on a circular knitted machine. Furthermore, the EMSE of the metal composite fabrics were evaluated by changing the lamination amounts and lamination angles. The results show that when the lamination amount was four, lamination angles were 0°/45°/90°/-45°, the EMSE of the fabrics reached to-10--20 dB in the frequency range of 300 KHz to 3 GHz.

Comparative analysis of pulsed Nd:YAG laser welding of 304L and 904L stainless steel

Wire and arc additive manufacturing (WAAM) produces thin-walled parts superior to other additive manufacturing methods, because of its high efficiency, good compactability, and low cost. However, the WAAM accuracy is limited by its large heat input. Here, 0.8 mm 316L stainless steel welding wire is deposited via speed cold welding to form 30-layered thin-walled samples, with 2 mm thickness, and up to 65 mm height. The effects of three process parameters (the bottom current mode, scanning speed, and cooling time) on the deposition process stability, macro morphology, structure, and mechanical properties are studied. In the experiment, the probability density curves of electrical parameters of sample #GRBC-30 cm/min-10 s on the third and tenth layers were narrower than other samples, which implied a more stable process. The three process parameters mainly affect the deposition morphology and have a minor performance effect. The hardness and tensile properties mainly depend on the deposition direction. Gradual, layer-by-layer current reduction improves the bottom molding and performance, and the deposition efficiency, and stabilizes the process. Scanning speed enhancement or cooling time reduction destabilizes the end formation, reduces the effective deposition rate, and slightly degrades the performance. All deposited samples are distinctly anisotropic, but satisfy the industrial standard. Overall, deposition in speed cold welding mode, with 10 s cooling time, 30 cm/min scanning speed, and gradually reduced bottom current exhibits good stability, and the molding efficiency and mechanical properties are optimal.

Mechanical polishing (MP), electropolishing (EP), and magnetoelectropolishing (MEP) were applied on 308L stainless steel (SS) weld cladding. The surface characteristics after surface treatment and the oxides after immersion in the primary water of a pressurized water reactor were studied. XPS results showed that the passive film of surface-treated MEP 308L SS had higher Cr/(Ni+Fe) than MP and EP 308L SS, and reported surface-treated MEP 316L SS. Transmission electron microscopy results showed that duplex-layer oxide films consisted of Fe-rich spinel outer crystals and Cr-rich inner layers were formed on all surface-treated 308L SS cladding after immersion. The inner oxide layers on austenite were Cr-rich spinel dominant oxides and much thicker than the chromia-dominant oxides on ferrite. MEP decreased the inner oxide layer thickness on austenite of oxidized 308L SS. The oxidation resistance of the ferrite matrix with higher Cr content was not obviously impacted by surface treatment. A higher Cr/(Ni+Fe) in the preformed passive film on the austenite was mainly responsible for the better oxidation resistance of MEP 308L SS cladding. The improvement of oxidation resistance by MEP on dual-phase 308L SS cladding was different from that on single-phase 316L SS, suggesting that a local heterogeneous passive film on surface-treated MEP 308L SS was more likely degraded to a duplex-layer oxide film compared to the single-layer one on MEP 316L SS.

The connecting pipe in solar hot water system is made by TIG welding of thin-walled stainless steel and copper. As the welding of stainless steel and copper belongs to dissimilar metal welding and their physical properties are very different, thus the welding of them is difficult and it is likely to cause a variety of defects in the welding process. In this paper, ANSYS software is used to simulate the welding process of stainless steel and copper, and the temperature distributions in the welding process are obtained. The results show that: as the heat transferring of copper is faster than stainless steel, the temperature field distribution of thin-walled stainless steel and copper tubes in the welding process is extremely uneven. As a result, the melting degrees on both sides in the welding seam are inconsistent, which may cause poor forming of weld seam. The results provide references and theoretical basis for the welding technology of dissimilar materials.

Aim The study aimed to evaluate the effect of two commercially available dentifrices on Nickel-Titanium and Stainless Steel orthodontic arch wires. Methods A total of 33 rectangular NiTi (0.019” x 0.025”) and 33 rectangular Stainless Steel (0.019” x 0.025”) wires were taken for this study. Each group containing 16 wires were treated with the following dentifrices; Group A - Colgate Strong Teeth Toothpaste Group B – PatanjaliDantKanti Toothpaste when mounted on typhodont with help of power toothbrush. the sample were scanned under Stereo Microscope at 35x magnification and Scanning Electron Microscope at 500x magnification to check whether the dentifrices have deleterious effects on the orthodontic arch wires. The recorded data was tabulated in MS-Excel and analyzed using one-way ANOVA. Statistical analysis was performed using SPSS statistical software at the 0.05 significance level. Descriptive statistics were done using the paired t- test for the intra group comparison and unpaired t- test for the inter group comparison. Results The SEM surface analysis revealed that the most surface variations were seen with the Stainless Steel arch wires treated with the Group A toothpaste followed by the Stainless steel wires treated with the Group B toothpaste. Both the groups demonstrated depressions, pores, furrows or grains in 1/3rd of the surface of the arch wire. However, the dimensions of the depressions, pores furrows was greater in the wires treated with Group A toothpaste when compared to the Group B toothpaste. Also, with the NiTiarchwires treated with the Group A toothpaste showed more surface variation compared to the NiTi wires treated with the Group B toothpaste. Both the groups demonstrated depressions, pores, furrows or grains in 1/3rd of the surface of the archwire. However, the dimension of the depressions, pores, furrows was greater in the wires treated with Group A toothpaste when compared to then Group B toothpaste. Conclusion The stainless steel archwires exhibited the maximum alterations in surface topography after treatment with both the dentifrices when compared to the Nickel-Titanium wires.

PG canine retraction spring

BackgroundThe aim of this prospective study was to compare root resorption after the leveling phase of treatment, performed by either super-elastic or conventional multi-stranded stainless steel arch wires.MethodsFrom a total of 156 future orthodontic patients in a private clinic, 82 were included in the study after excluding those who earlier had orthodontic or endodontic treatment or signs of resorption. Patients were equally arbitrary allocated into two groups, where leveling was performed either with super-elastic heat-activated or conventional multi-stranded stainless steel arch wires. Root length loss was calculated using pre-treatment and post-leveling periapical radiographs.ResultsThe use of super-elastic arch wires did not significantly increase the severity of root resorption, except for tooth 31, while it reduced leveling time compared to conventional stainless steel wires. Crossbite of maxillary lateral incisors seemed to be a risk factor for resorption.ConclusionIncisor root resorption after leveling did not differ significantly between patients treated with super-elastic and conventional stainless steel arch wires, except for a mandibular incisor.Electronic supplementary materialThe online version of this article (doi:10.1186/s40510-014-0035-z) contains supplementary material, which is available to authorized users.

This study investigates the effect of dissimilar metal welding of low nickel stainless steel (SS) and 304 SS employing tungsten inert gas (TIG) welding process by using three different filler materials (316L, 308L and 310 SS). Microstructural, mechanical properties and corrosion behavior in 3.5% NaCl solution was studied. The microstructural investigation revealed the formation of δ-ferrite and γ-austenite in the weld (welded by 316L and 308L filler). The Higher δ-ferrite content was found more in 316L weld zone. Whereas samples welded by 310 SS filler showed the columnar structure in the weld zone. Relatively wider heat affected zone (HAZ) was measured on Cr-Mn SS side as compared to 304 SS side. Impact fracture surface of all the welded samples exhibited dimple appearance. Corrosion studies showed better pitting corrosion resistance in 316L SS welded sample due to the beneficial effect of δ-ferrite and also the addition of molybdenum (Mo). Electrochemical impedance spectroscopy (EIS) revealed higher polarization resistance (Rp) in 316L SS as compared to other fillers. Galvanic current density was found to be higher in Cr-Mn SS as compared to 304 SS when coupled with different welded samples.

A field study was conducted to estimate the amount of Cr, Mn, and Ni deposited in the respiratory system of 44 welders in two facilities. Each worker wore a nanoparticle respiratory deposition (NRD) sampler during gas metal arc welding (GMAW) of mild and stainless steel and flux-cored arc welding (FCAW) of mild steel. Several welders also wore side-by-side NRD samplers and closed-face filter cassettes for total particulate samples. The NRD sampler estimates the aerosol's nano-fraction deposited in the respiratory system. Mn concentrations for both welding processes ranged 2.8–199 μg/m3; Ni concentrations ranged 10–51 μg/m3; and Cr concentrations ranged 40–105 μg/m3. Cr(VI) concentrations ranged between 0.5–1.3 μg/m3. For the FCAW process the largest concentrations were reported for welders working in pairs. As a consequence this often resulted in workers being exposed to their own welding fumes and to those generated from the welding partner. Overall no correlation was found between air velocity and exposure (R2 = 0.002). The estimated percentage of the nano-fraction of Mn deposited in a mild-steel-welder's respiratory system ranged between 10 and 56%. For stainless steel welding, the NRD samplers collected 59% of the total Mn, 90% of the total Cr, and 64% of the total Ni. These results indicate that most of the Cr and more than half of the Ni and Mn in the fumes were in the fraction smaller than 300 nm.