Papers by Keyword: 316 Stainless Steel

Abstract: Triply Periodic Minimal Surfaces (TPMS) structures, such as the Gyroid, can exhibit nearly isotropic mechanical behaviour over specific relative density ranges, as predicted by the Zener anisotropy ratio. In contrast, the Laser Powder Bed Fusion (L-PBF) process may induce anisotropy in the material due to thermal gradients and residual stresses, potentially influencing the overall structural response. This work investigates how the anisotropy generated by the L-PBF process interacts with the inherent isotropy of Gyroid architecture. Gyroid lattices in 316L stainless steel were produced with varying unit cell sizes and wall thickness. Quasi-static compression tests were performed along directions parallel and perpendicular to the build axis to evaluate orientation effects. Numerical simulations, using both isotropic and anisotropic material properties, were employed to estimate the effective elastic response and the Zener anisotropy ratio. The combined experimental and numerical study aims to assess whether and to what extent the Gyroid architecture partially mitigates the transmission of process-induced anisotropy to the effective elastic response, contributing to a better understanding of the mechanical behaviour of additively manufactured metallic lattices. In particular, the study clarifies whether the theoretically isotropic Gyroid architecture is able to attenuate or transfer L-PBF-induced material anisotropy at the lattice scale.

Abstract: The objective of this study is to investigate and determine the effect of the stand-off distance (distance between the welded plates) on the mechanical properties of the Tungsten Inert Gas (TIG) welded joints. Butt TIG welding was performed for 316 stainless steel (SS) by using different pre welding stand-off distances with fixing the other parameters (thickness of welded plates, voltage, current, groove shape, and scanning speed). The influence of the stand-off distance parameter was examined by using tensile test, hardness test in the three different regions (base metal, heat effected zone, and molten zone), non-destructive testing (including visual inspection, liquid pentrant and X – ray) and microscopic examinations. Results show that the stand-off distance is one of the most important geometrical parameters of the Butt welded joints to end by good mechanical properties. It is found that the optimum stand-off distance was about 1 mm (shows the highest hardness results), but still there were some defects in some spots in the molten metal zone which caused a decrease in the hardness values in these locations. The 2 mm stand-off distance shows reasonable results, and the worst case was recorded for the 0 mm stand-off distance condition. Generally the hardness values of the heat affected zone in all conditions were the highest when compared to both metal welding zone and the base metal zone.

Abstract: The corrosion characteristics of 316SS and 304SS in subcritical and supercritical aqueous systems including chloride of approximate 4600 mg/L at 25 MPa and 250 °C, 350 °C, 425 °C, and 520 °C are comparatively investigated. Some local corrosion areas occurred on the surfaces of SS316, not on that of 304SS, at 250 °C and 425 °C, while at 350 °C, all the sample surfaces were covered by large amounts of corrosion products and clay materials due to the predominant precipitation for the formation of the outer subscale. Whether in reducing subcritical and supercritical industrial sludge suspension or in oxidizing supercritical sludge system, 304SS owns better corrosion resistance than 316SS due to higher chromium concentration of former.

Abstract: In this work the biaxial behavior of 316 stainless steel is studied under the lens of critical plane approach. A series of ten experiments were developed on dog bone shape hollow cylindrical specimens made of type 316 stainless steel. Five different loading conditions were assessed, with (i) only axial stress, (ii) only hoop stress, (iii) proportional combination of axial and hoop stresses, (iv) non-proportional combination of axial and hoop stresses with square shape and (v) non-proportional combination of axial and hoop stresses with L-shape. The fatigue analysis is performed following four different critical plane theories, namely Wang-Brown, Fatemi-Socie, Liu I and Liu II. The efficiency of all four theories is studied in terms of the accuracy of their life predictions.

Abstract: The influence of martensitic transformation on the fatigue of AISI 316 type stainless steel, which presents a low temperature metastable behavior, was investigated at-196 and 25°C. Fatigue tests were conducted on both annealed and cold worked conditions. The results from stress versus number of cycles curves showed that the fatigue resistance is not affected by the “dynamically” induced martensite in annealed specimens at both temperatures. On the contrary, the previously induced “static” martensite in work hardened specimens contributes to decrease the fatigue resistance limit. The contribution of the martensite stability is discussed.

Abstract: In this paper, metallographic examination, visual examination and scanning electron microscopy were used to analyze the perforation failure of the differential pressure transmitter impulse pipe. Macrostructure and microstructure of the hole, corrosion characteristics, and corrosion products were studied. Combined with the service conditions of natural gas pipe, relationship between the pipe material quality and the formation process of the perforation failure was determined utilizing fracture mechanics and corrosion analysis. The perforation failure may be caused by the defects and stress corrosion.

Abstract: This paper mainly introduces the mechanism of microwave heating: electric conduction loss, eddy current loss and arc discharge. The microwave heating behavior of 316 stainless steel powder body which made by gel casting was investigated in the paper. Experiments on different microwave power, powder particle size, and the content of auxiliary heating material showed that the smaller the powder particle size, the larger microwave power and auxiliary heating materials help 316 stainless steel body for sintering.

Abstract: Corrosion rate, corrosion potential and susceptibility to pitting corrosion of a metal are measured using cyclic polarization Direct Current (DC) electrochemical technique. The aim of the present research is to investigate the pit nucleation resistance of polished, ground and passivated surfaces of 316 stainless steels in Ringers solution. The electrochemical cyclic polarization results showed that polished surface gave better pitting resistance as compared to ground surface. It was also observed that passivation treatment gave better pitting resistance to both polished and ground surface of 316 stainless steels in Ringers solution.

Abstract: Hot deformation characteristics of 316 stainless steel were investigated at elevated temperatures. Hot compressive tests were carried out in the temperature and strain rate ranges from 900 to 1100 °C and 1 × 10⁻¹ to 1 s^–1, respectively. Correlation between the flow behavior and the microstructural evolution was analyzed. The flow behavior showed that the softening mechanisms were related to the dynamic recovery (DRV), dynamic recrystallization (DRX), and grain growth. Flow behavior analyses and microstructural observations indicated that DRV was the major softening mechanism at high strain rates and low temperatures. Dynamic softening proceeded via a combination of DRV and DRX at intermediate strain rates and temperatures. The contribution of DRV to the softening effect decreased with decreasing strain rate (or increasing temperature). Grain growth was the major softening effect at low strain rates and high temperatures.

Abstract: The experimental investigations on resistance spot welding are presented for 316 stainless steel. The influence of spot welding parameters (welding time, electrode force and welding current) on the tensile shear load and the diameter of nugget have been researched, based on an orthogonal test and analysis method. The results show that welding current has significant influence on the tensile shear load and diameter of nugget, and then is electrode force, welding time in turn. The optimum parameters are as follows: welding time is 5 cycles, electrode force is 3.5KN and welding current is 5.5KA. And the maximum tensile shear force of joint is up to 13.55KN.