Incorporation of AWS 316L wire nanostructured with nickel-carbon nanotube by arc welding

Abstract

Carbon nanotubes have certain properties, such as 150 GPa tensile strength, a 1000 GPa shear modulus, an electrical conductivity of 60 S/m, and a high thermal conductivity of 2500 W/mk, that make them an optimum metallic matrix composite reinforcement. Otherwise, arc welding is a common industrial process that joins almost all metals. However, there are hardly any studies involving the addition of carbon nanotubes in stainless steel so far. In this research, we show the incorporation of an AWS 316L nanostructured wire with nickel-carbon nanotubes in austenitic stainless steel via pulsed gas tungsten arc welding, which formed nanocomposites with 0.75 and 1.5 wt% carbon nanotube contents in the wire. The characterization was performed by scanning electronic microscope, Raman spectroscopy, and X-ray diffraction. The Vickers microhardness test was used to analyze the mechanical properties. The nanostructure composite had microstructure modification, and superficial microhardness improved in 35% for 0.75 wt% carbon nanotube.

Effects of CNTs addition on the microstructure and microhardness of stainless steel alloy/carbon-manganese non-alloyed steel welding

“…The microhardness percentages were calculated based on indentation data in topside and cross-section of WM with nanocomposite compared to its own BM. Although they using the same process, the WM/BM welding with similar materials, 6,7,13 not is appropriately compared with our results, because our WM/BM were a dissimilar materials. However, despite that is evident the reinforcement effect of the CNTs in the weld metals.…”

“…MWCNTs with a purity of 95.7% were synthesized by chemical vapor deposition and provided by CTnanotubos. These nanomaterials were dispersed in ultrasonic bath under 40 kHz at room temperature with cetyltrimethylammonium bromide (CTAB) as surfactant and polyacrylic acid (2 g/L) in order to avoid agglomeration of the CNTs, as performed by Loayza et al 6 and Arai et al 15 Electrolytic bath was prepared with nickel chloride (0.2 mol/L), nickel sulfate (1.0 mol/ L), boric acid (0.5 mol/L), CTAB and MWCNTs with 2.0 g/L each. During electrochemical deposition a pure nickel electrode and SS 316L core were placed as anode and cathode, respectively.…”

“…2 In last years, the CNTs are used as reinforcement in metal matrix and they are added by several techniques, such as thermal spray, 3 chemical vapor infiltration process, 4 powder metallurgy, 5 and, more recently, by arc welding. 6,7 Many studies have shown that the one-dimensional structure of CNTs is helpful to improve the mechanical properties and change the microstructure of stainless steel (SS) metal matrix. Kaewsai et al 3 reported that hardness of SS/CNTs coating was 58.41% higher than pure SS coating.…”

“…Recently, Loayza et al 6 investigated the incorporation of CNT in SS alloys by pulsed Gas Tungsten Arc Welding (P-GTAW) in which utilizes an inert gas shielded arc produced by a non-consumable tungsten electrode with a SS consumable electrode made of a coated and tubular wire welded on a base metal made from same material. In the first report, the arc welding was performed using a wire electrode of SS 316L alloy coated with nickel-MWCNTs nanocomposite, where the topside microhardness was 35% higher than the sample control and unusual dendrite structures were observed in the microstructure.…”

Stainless steel weld metal enhanced with carbon nanotubes

“…The Pulsed one (P-GTAW) generates finer grains, increasing the performance of the weld metal, and contributes with the dispersion of elements alloys, which supports the fabrication of nanocomposites as it helps to avoid the vaporization of the nanomaterials and improves its dispersion in the weld metal. The GTAW has been used to manufacture nanostructured composites with Al/TiC 29 , Nickel-CNT 30 , and Al-CNT 31 as additional material. Although several metal matrices were incorporated in a weld joint, researches involving stainless steel (SS) are still underdeveloped, as their high melting point is very destructive for the structure of the CNTs.…”