Stainless Steel Lattice Research Articles

选区激光熔化碳化钒颗粒强化316L不锈钢的点阵结构及性能

选区激光熔化碳化钒颗粒强化316L不锈钢的点阵结构及性能

SCC susceptibility of solution-annealed 316L SS in hydrogenated hot water below 288 °C

Stress corrosion cracking (SCC) susceptibility of solution-annealed 316L stainless steel was evaluated by slow strain rate test in oxygenated, deaerated and hydrogenated water below 288 °C. At 288 °C, no SCC was found in the specimens tested in oxygenated water, while in hydrogenated water, SCC occurred irrespective of dissolved-hydrogen (DH) content in the late stage of deformation where cold-working was followed by necking. The SCC susceptibility diminishes as temperature decreased from 288 °C to RT, which was accompanied by a reduction of oxide film thickness. At 220 °C, SCC occurred at the highest DH content only, which suggests a combined effect of DH content and test temperature on the SCC susceptibility. The combined effect can be explained by anodic reaction rate, hydrogen diffusion rate and hydrogen trapping ability. The SCC susceptibility appeared to increase with DH content, which was reasonably explained by suppression of the protective oxide film formation on specimen surface and increasing hydrogen content in the specimen. Based on an SCC model that hydrogen reduces cohesive force in austenitic stainless steel lattice, the SCC behavior can be interpreted in terms of hydrogen-assisted SCC (HASCC) where corrosion-induced hydrogen production, suppression of the formation of protective oxide film caused by hydrogen, work-hardening, and hydrogen-induced reduction of cohesive force of the lattice atoms are necessary.

Mechanical properties of an improved 3D-printed rhombic dodecahedron stainless steel lattice structure of variable cross section

A new modified rhombic dodecahedron lattice structure is proposed by redefining the cross section of the struts of the original one with a shape parameter, and the detailed design method of the proposed lattice structure is also provided. For verification, some representative configurations of the proposed lattice structure were 3D-printed via Selective Laser Melting (SLM) with the material 316 L stainless steel. Quasi-static compression test of the fabricated samples was conducted. Finite element model was also established to investigate the mechanical properties of all the as-designed configurations. Finite element results are in good agreement with the experiment results. Compared with the original lattice structure, the proposed one exhibited better mechanical properties and energy absorption. In addition, the effects of the shape parameter on the deformation mode and the mechanical properties of the rhombic dodecahedron (RD) lattice structures were also discussed, while an optimal shape parameter of the proposed RD lattice structure is obtained.

Elastic modulus of 316 stainless steel lattice structure fabricated via binder jetting process

This study mainly evaluates the elastic modulus of 316 stainless steel lattice structures fabricated via binder jetting process. In this present research, both solid and lattice samples are designed and fabricated by binder jetting process for two different types of mechanical tests. Besides experimental study, a numerical model based on energy approach has been proposed to predict the effective elastic modulus of fabricated lattice samples. By comparing the calculated results of the proposed numerical model with the experimental results, the established model is proved to be validated. This numerical model can be used to determine the parameters of lattice structures fabricated by binder jetting process for desired mechanical properties. At the end, both advantages and disadvantages of the lattice structures fabricated by binder jetting process are analysed. Based on this analysis, the potential application and future research work are pointed out.

Mechanical behavior of open-cell rhombic dodecahedron Ti–6Al–4V lattice structure

The compression behavior of Ti–6Al–4V lattice structure with a cell shape of rhombic dodecahedron, which was fabricated by electron beam melting, was investigated at different temperatures. A series of quasi-static compression tests were performed at ambient temperature, 200°C, 400°C and 600°C with a strain rate of 10−3s−1. Two groups of design configurations were adopted by changing the cell size and thickness of struts with the sample size maintained unchanged. The results revealed that their properties varied with different cell sizes and temperatures. Larger cell size leaded to lower modulus and strength of the lattice. Higher temperatures resulted in lower strengths, modulus, densification strains and plateau stresses. The energy absorption of lattice at high temperature was discussed, and the experimental data were compared with aluminum foams, titanium foams and stainless steel lattice. It demonstrated that the rhombic dodecahedron Ti–6Al–4V lattice structure could be applied as load-bearing components and energy absorber at high temperature.

Mechanical response of TiAl6V4 lattice structures manufactured by selective laser melting in quasistatic and dynamic compression tests

This paper focusses on the investigation of the mechanical properties of lattice structures manufactured by selective laser melting using contour-hatch scan strategy. The motivation for this research is the systematic investigation of the elastic and plastic deformation of TiAl6V4 at different strain rates. To investigate the influence of the strain rate on the mechanical response (e.g., energy absorption) of TiAl6V4 structures, compression tests on TiAl6V4-lattice structures with different strain rates are carried out to determine the mechanical response from the resulting stress-strain curves. Results are compared to the mechanical response of stainless steel lattice structures (316L). It is shown that heat-treated TiAl6V4 specimens have a larger breaking strain and a lower drop of stress after failure initiation. Main finding is that TiAl6V4 lattice structures show brittle behavior and low energy absorption capabilities compared to the ductile behaving 316L lattice structures. For larger strain rates, ultimate tensile strength of TiAl6V4 structures is more than 20% higher compared to lower strain rates due to cold work hardening.

Low-velocity impact performance of lattice structure core based sandwich panels

This paper outlines the findings of a study on a range of stainless steel and titanium alloy lattice structures manufactured using the selective laser melting technique. The effect of varying key manufacturing parameters on the properties of lattice strands was studied through a series of single-filament tensile tests. The resulting failure mechanisms were investigated using a scanning electron microscope. The resulting observations have shown that the properties of these lattice strands are determined by the laser energy during the manufacturing process, which in turn is controlled by the laser power and laser exposure time. The quasi-static and low-velocity penetration behaviour of lattice core-based sandwich panels has been examined, and an aluminium foam and an aluminium honeycomb were chosen to benchmark their performance. The impact resistance of the lattice core-based sandwich structures were shown to be dependent on both the manufacturing parameters and lattice unit-cell geometry of the lattice structure. The impact resistances were improved by increasing manufacturing laser energy and lattice core density. A series of drop-weight tests at velocities up to 6 m/s have shown that the penetration behaviour of the titanium alloy lattice cores and the aluminium honeycomb cores is similar.

The Effects of a Carbon Ion Implantation Technique on In-stent Restenosis: Korean Multicentered Randomized Trial

Background and Objectives:Heavy metal ions released from a stainless steel stent can induce an inflammatory reaction that might be associated with in-stent restenosis. A carbon ion implantation technique, which physically integrates carbon ions into the surface of the stainless steel lattice, can block heavy metal ion diffusion, and improve the biocompatibility. This study was designed to evaluate the efficacy of a carbon ion implanted Arthos stent on the reduction of in-stent restenosis and the improvement in the clinical outcomes. Subjects and Methods:193 de novo coronary lesions in 191 anginal patients at 14 centers, with reference diameters from 2.75 to 4.5 mm, were randomly assigned to either an Arthos (100 patients, 102 lesions) or an Arthos (91 patients, 91 lesions) stent. The lesion length was 14.1±5.7 mm. The ACC/AHA (American College of Cardiology/American Heart Association) lesion classifications were A:15.0%, B1:36.8%, B2:35.8% and C:12.4%. The study end points are angiographic restenosis, during a six-month follow-up, and Major adverse cardiac event. In-stent restenosis was defined as a diameter of stenosis ≥50%. Results:A six-month angiographic follow-up was obtained for 72.3% (138/191) of the subjects. There were no significant differences between the Arthos and Arthos groups in the rates of restenosis (17.8% vs. 31.8%, p=0.055) and Target vessel revascularization (7.0% vs. 11.0%, p=0.476). There were no deaths or non-fatal myocardial infarction in either group. Conclusion:The treatment of de novo coronary stenosis, with carbon ion implanted stents, showed a tendency for lower six-month angiographic restenosis rates than the conventional 316L stainless steel stents. A larger trial will be needed to confirm the efficacy of the carbon ion implanted stent. (Korean Circulation J 2004;34(5): 477-484)

Steam treatment of sintered iron and steel parts: P. Beiss (Sintermetallwerk Krebsöge, Radevormwald, Germany), Powder Metallurgy, Vol 34, No3, 1991, 173–177

The steam generators (SGs) used in pressurized heavy water reactors (PHWRs) are the vertical, inverted U-tube type, commonly seen in pressurized water reactors (PWRs). The function, sizes, operating conditions, etc. are very similar to PWR SGs. The design of the SGs for PHWRs has evolved over a 60-year span, and now includes stainless steel lattice grid tube supports, predominantly alloy 800 tubes of 13–16 mm diameter, and advanced high-performance steam/water separators. The design has been adapted successfully for use as replacement and new SGs in PWR.