Pulsed-DC powder-pack boriding: Growth kinetics of boride layers on an AISI 316 L stainless steel and Inconel 718 superalloy

Author(s):  
I. Campos-Silva ◽  
E.J. Hernández-Ramirez ◽  
A. Contreras-Hernández ◽  
J.L. Rosales-Lopez ◽  
E. Valdez-Zayas ◽  
...  
2019 ◽  
Vol 38 (2019) ◽  
pp. 792-805 ◽  
Author(s):  
S. Ramakrishna Kandala ◽  
Kantesh Balani ◽  
Anish Upadhyaya

AbstractThe present study compares the mechanical properties and electrochemical behaviour of austenitic (AISI 316 L) stainless steel compacted at different pressures (200, 400 and 600 MPa), which are conventionally sintered at supersolidus temperature of 1,400°C. As expected, increase in compaction pressure (from 200 MPa) to 600 MPa has shown decreased shrinkage (from 7.3% to 4.2% radial and 5.5% to 3.4% axial, respectively) and increased densification (up to ~92%). Their electrochemical behaviour was investigated in 0.1 N H2SO4 solution by potentiodynamic polarization and electrochemical impedance spectroscopy. The mechanical properties (such as yield-, tensile- and transverse rupture strength) and electrochemical behaviour with pressure have been correlated with densification response and microstructure (pore type, volume and morphology). Highest densification (~92% theoretical) achieved at 600 MPa (compaction pressure) and 1,400°C (sintering temperature) resulted in excellent combination of tensile strength and ductility (456 ± 40 MPa and 25 ± 1.1% respectively), while showing lowest corrosion rate (0.1 mmpy or 4.7 mpy) due to the presence of isolated porosity in the sintered samples.


2015 ◽  
Vol 830-831 ◽  
pp. 314-318 ◽  
Author(s):  
S. Shashi Kumar ◽  
N. Murugan ◽  
K.K. Ramachandran

The present investigation is carried out to investigate on mechanical and metallurgical properties of Friction stir (FS) / Underwater Friction stir (UFS) welded 3 mm thick AISI 316 L stainless steel joints. Experiments were carried out at a tool rotational speed of 700 rpm, welding speed of 45 mm/min and axial force of 12 kN. Defect free joints were confirmed by visual inspection. A marginal rise of about 4.5 % increase in the joint strength is achieved in water cooling than by gas cooling technique. Reduced peak temperature in water cooled joint led to better grain refinement in the weld nugget enhancing FSW tool life. No sign of secondary phase precipitation was observed in the weld joints which was confirmed by Energy Dispersive Spectroscopy (EDS) spectrums and micro etchants like Groesbeck and modified Murakami reagents in the weld nugget.


1992 ◽  
Vol 13 (2) ◽  
pp. 151-160
Author(s):  
G. Moretti ◽  
G. Quartarone ◽  
A. Tassan ◽  
A. Zingales

2010 ◽  
Vol 660-661 ◽  
pp. 454-459 ◽  
Author(s):  
Maurício David Martins das Neves ◽  
Luzinete Pereira Barbosa ◽  
Luís Carlos Elias da Silva ◽  
Olandir Vercino Correa ◽  
Isolda Costa

Stainless steel (SS) powders are used in the preparation of sintered SS products. One of the applications of sintered SS products is as filters in the petrochemical and food processing industries. In these industries, the SS filters are subject to severe conditions associated with the removal of solid particles from the fluid. Hence, SS filters should have adequate mechanical strength and high corrosion resistance. Welding can be used to manufacture SS filters. In this study, sintered AISI 316L specimens were welded using the TIG (Tungsten Inert Gas) process. The weld joints were examined by optical microscopy and by scanning electron microscopy. Electrochemical polarization measurements were carried out to evaluate the influence of welding on the corrosion resistance of sintered filters.


Author(s):  
João PM Pragana ◽  
Ivo MF Bragança ◽  
Carlos MA Silva ◽  
Paulo AF Martins

This paper is focussed on the mechanical and formability characterisation of wire-arc additive manufactured (WAAM) AISI 316-L stainless-steel tubes. The methodology to be presented involved carrying out tension and ring hoop tension tests on specimens extracted from the tube longitudinal, transverse and inclined directions. The force evolutions, acquired from the load cells, and the strain measurements, retrieved from digital image correlation and from thickness measurements along the cracks, allowed obtaining the stress-strain curves, the strain paths and the onset of failure by fracture for the three different tube directions. Special attention was paid to the ring hoop test, which was revisited to determine the appropriateness of using ring specimens with one or two dumbbell geometries. The originality of using the ring hoop tension test in WAAM tubes with strong anisotropic behaviour allowed obtaining strain loading paths that range from plane strain to pure shear deformation conditions. Resort to commercial AISI 316-L stainless-steel tubes during the presentation is included for reference purposes.


2020 ◽  
Vol 62 (6) ◽  
pp. 652-656
Author(s):  
Özlem Aydın ◽  
Polat Topuz ◽  
Tuna Aydgomus

Abstract This paper presents the growth kinetics of the boride layer formed on a boronized AISI 316 (X5CrNiMo17-12-2) stainless steel surface. Samples were boronized applying the Ekabor 2™ boronizing agent in an atmosphere controlled furnace at 1073, 1173 and 1273 K for 1, 2 and 3 h by the powder pack method. Surfaces of the samples which have completed the boronizing process were prepared for metallographic examinations. An optical microscope and an integrated image analyzer were used to measure the thickness of the boride layer formed on the surface of the samples. Due to the dual phase structure of the boride layer formed on the steels in order to see these phases in detail, an SEM (Scanning Electron Microscope) image of the sample was taken with the help of the back scattered electrons. In addition, for determination of the elements constituting these phases, elemental analysis was carried out with the help of an EDS (Energy Dispersive Spectroscopy) unit connected to SEM. Then XRD (Xray diffraction analysis) analyses were carried out to understand in detail which phases formed the boron layer. For hardness measurements of boride layers, a Vickers hardness device with 100 g weight was used. Finally, to determine the growth kinetics of the boronized samples, calculations were made with the help of the Arhenius equation and compared with the literature.


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