Papers by Keyword: 316L Stainless Steel

Abstract: Several case studies have shown that welding of stainless steel to galvanized steel leads to evolution of zinc which can penetrate through the steel and result in cracking, the present study focuses on determination of the effect of zinc on the mechanical behaviour of such weld joints. Welding was carried out using two shielding gas combinations. The other variations in parameters were heat input and presence or absence of zinc coating at the weld location. Tensile tests showed that the ductility of weld specimen improved when the coating was stripped off the samples prior to welding. Impact strength of weld specimens also followed similar trend. The impact strength was found to be improved when welding was done using Ar+2%He+2%O₂ as shielding gas. The compressive strength was found to be similar. To explain the mechanical behaviour of the welded specimen, microstructural characterization of the weld region was carried out.

Abstract: Creep does not only appear at high temperature, but also appears at low temperature for 316L stainless steel that threatens the safety of equipment. In this work, the creep behavior of as-received and pre-strained 316L stainless steel at 373K was investigated by uniaxial creep (UC) tests and small punch creep (SPC) tests. The parameters of power-law creep model were determined from stress dependence of UC tests. Then, the creep behavior of SPC test was analyzed by finite element (FE) simulation combined with power-law creep model. Comparing with experimental creep deflection, the results of FE simulation can reasonably reflect the creep behavior of as-received and pre-strained small punch specimens. Based on the comparison of as-received specimen and pre-strained specimen from UC test, SPC test and FE simulation, pre-strain significantly restrains creep behavior of 316L austenitic steel at 373K.

Abstract: Water droplets formed by the deliquescence of pre-deposited NaCl on 316L stainless steel were investigated. Different total weights of NaCl particles between 0.0005 g and 0.01 g were deposited on 316L stainless steel surface, which were exposed to an atmospheric condition at 80oC and relative humidity of 80% until NaCl droplets were stabilized. The volume of NaCl droplet was linearly proportional to the total weights of pre-deposited NaCl and consequently the chloride concentration in droplets, ranging from 3 to 6 M, did not depend on the NaCl weights. After exposed to the NaCl droplets at 80oC and relative humidity of 80% over 5, 10, and 15 days, all 316L stainless steel samples suffered from pitting. The Cl^- ions in the surface films of samples were measured by ToF SIMS. The pit densities on samples were well correlated with the Cl^- intensities in the surface films. These results suggest that the pit initiation under NaCl droplets by deliquescence is caused by the Cl^- ions either incorporated into surface films or penetrated through them.

Abstract: In the past few decades, Metal Injection Moulding (MIM) has evolved as a new revolutionary metalworking process for medical implant fabrication in orthopaedics. The technology employs natural resources in a minimum outlay without compromising the quality of its end products. This metalworking process allows the production of a high volume complex prosthetic implants that can be shaped in a single operation and cost productive. In this study, we evaluated the potential of MIM 316L stainless steel as the internal fixation plate in a long bone fracture using rabbit model. The study was approved by the International Islamic University Malaysia Research Ethics Committee. Experimental fractures were made at the rabbits’ tibia and fixed with either MIM plate or AO/ASIF mini plate, as control. The assessments were carried out by means of radiography procedure and histological evaluation at each time point of 3, 6, 9, 12 and 26 weeks post-operatively. Hard tissue processing was used since all samples comprised bone tissue and metal plate. Based on the observation, there were callus formations in both MIM and control groups at week 3 post-operatively. Bone union was evidenced starting week 6, whilst bone remodelling was completed at week 26. Histological assessment indicated that both groups possessed mild to moderate callus bridging at week 3 and week 6, respectively. While complete remodelling bone cortex was evidenced at week 26. Taken together, these findings indicate that the potential of MIM plate to hold the tibial fracture is comparable to that of AO/ASIF plate. Apart from being cost productive, the production of MIM plate also utilizes natural resources. Therefore, the MIM plate can be used as an alternative internal fixator for bone fracture management in orthopaedic.

Abstract: Optimization of solvent debinding process parameters for powder injection molded 316L stainless steel (SS) has been reported in this research work. Powder gas atomized (PGA) 316L SS was blended with a multicomponent binder in Z-blade mixer at 170°C ± 5°C for 90 minutes. Feedstock was successfully injected at temperature 170 ± 5°C. Injection molded samples were immersed in n-heptane for 2h, 4h, 6h and 8h at temperatures 50°C ,55°C and 60°C to extract the soluble binder components. Scanning electron microscope (SEM) results attested that soluble binder components were completely extracted from injection molded samples at temperature 55°C after 6h.

Abstract: The aim of this work is to investigate the effect of sandblasting and electropolishing on roughness and corrosion rate of AISI 316L stainless steel. The equipment used was sandblasting machine with a working pressure of 5-7 kg/cm2 with a duration of 10 minutes. The silica sand was used with size of 500-800 μm. The equipment used in the electropolishing process is the DC power supply with a maximum output of 2x100A. Anode and cathode material were AISI 316L stainless steel. Electrolyte solution consisted of 96% mass fraction of sulfuric acid and 85% mass fraction of phosphoric acid with a ratio of 1. The parameters used in the electropolish process were voltage, electrodes distance and electropolishing duration process. The combination of sandblasting and electropolishing cause the decrease in surface roughness by more than 28 times, from 3.17 to 0.11 μm. The decrease in the rate of corrosion on specimens that have been treated sandblasting and electropolishing by 37%. The optimum parameters for testing surface roughness and corrosion rate contained in the sandblasting process electropolishing for 10 minutes with a distance of 1 cm, duration 20 minutes and voltage 8V.

Abstract: In this research, sol-gel method was utilized to prepare ceramic coating on medical grade 316 L stainless steel with different annealing temperature, solution constitute and coating layers. As-prepared zirconia film morphology was characterized by scanning electron microscope. The human umbilical vein endothelial cells (HUVECs) were cultured on specimens to evaluate their biocompatibility, with fluorescence staining to observe the morphology of cells. The results showed that annealed zirconia film was improved mechanical properties. According to the bio-evaluation results, HUVECs shows very small difference on proliferation activity on ZrO₂ coatings compared to 316 L stainless steel, which was shows high difference on proinflammation response test. This indicated that ceramic coating can be indeed less aggressive, which was use for potential future application in surface treatment of stainless steel in scalpels and indwelling needle.

Abstract: This paper investigates the numerical simulation of the sintering stage by solid state diffusion during the metal injection molding process for micro-bi-material component based on a thermo-elasto-viscoplastic model. The physical parameters concerning very fine 316L stainless steel and copper powders with high volume loading contents involved in the sintering model have been identified in order to set up finite element simulations. The experimental tests have been carried out in a vertical dilatometer and the identification of the material parameters have been carried out with Matlab^® platform software. Then in order to predict the shrinkage and relative density after densification, a solid state diffusion model for the sintering has been implemented in finite element software to perform the simulation of the sintering stage.

Abstract: Different heat source had been investigated for thermally enhanced machining on various engineering materials. Even so, temperature control from the heat source remained a challenged to the process effectiveness.This study used oxyacetylene combustion flame as a heat source in heat assisted machining. The study focuses on the relationships between process conditions; maximum temperature distribution and the surface integrity of 316L stainless steel during preheat machining as compared to dry hard part machining. Two levels of cutting speed 1000rev/min, 630rev/min and feed rates 160mm/min and 100mm/min were investigated while the depth of cutting was maintained constant at 1mm. While preheat machining for 60seconds along the span of the work piece material at cutting speed 1000 rev/min and feedrate 100mm/rev, the average surface finish have improved by 94% over dry hard part machining. This corresponds to flank wear VB = 0.0644mm during heat assisted machining and 0.1425mm for dry hard part machining respectively. Such improvement was accompanied with longer tool life and secured surface integrity which improves the material’s life cycle.

Abstract: The paper presents the results of strength and fatigue life of porous sintered 316L stainless steel. Samples with different porosity ( 26%, 33% and 41%) were tested. Graphs of fatigue life were obtained. Both areas of crack initiation propagation and destructions of the samples were determined.