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20a??kW laser welding applied on the international thermonuclear experimental reactor correction coil case welding
摘要： International thermonuclear experimental reactor correction coil cases are made of heavy, thick, high strength, and high toughness austenitic stainless steel 316LN. The BTCC (bottom and top correction coils) case has the dimension of 2.5 × 7 m2 and cross section of 239.8 × 146.7 mm2, side correction coil case has the dimension of 7.2 × 7.6 m2 and cross section of 147.8 × 168 mm2, and they will be closure welded after winding pack insertion. The 20 mm welding depth, dozens of meter of welding length, strict welding requirements, large size, and complex configuration bring a big challenge to this closure welding work. 20 kW high power laser welding is selected as the main welding method because of the advantage of potential welding deformation control and its penetrating ability and cracking resistance. The welding parameter is developed that can cover the assembly gap from 0 to 0.5 mm with a good welding quality. A special test coupon is designed for the welding procedure qualification, and related tests are carried out to qualify the joint properties of bend, tensile, and impact. Finally, a full-scale BTCC case is welded. After welding, ultrasonic testing confirms that almost all welds satisfy the weld seam quality requirement. The recorded temperatures less than 250° indicate that the temperature induced by welding will not harm the internal winding pack. The dimensional deviation of the inner face is less than 4 mm and also satisfies the tolerance requirement of ±2 mm for the BTCC case.
关键词： austenitic stainless steel,ITER,welding deformation,cracking,20kW laser welding
更新于2025-09-23 15:21:01
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Laser Ablation of Stainless Steel in Water and Hexane: Characterization of Surface Modification and Nanoparticles for Various Applications
摘要： This work investigates the effect of a liquid medium on the roughness and the chemical composition of an ablated, stainless steel target, as well as on various properties of the laser-generated nanoparticles, such as absorption, hardness, and yield; in addition, some possible applications of laser ablation in both water and hexane are suggested. It is found that changing the liquid medium from hexane to distilled water not only changes the chemical composition of the target, but also reduces the mass ejected from the target by roughly 25%. Further, this change leads to a “smoother” ablation process and reduces the roughness of the target. Finally, mixed results were obtained when changing the liquid medium. Nanoparticle properties such as yield and absorption were found to be greatly affected, while mechanical properties, such as hardness, are not dependent on the liquid medium.
关键词： confined plasma,nanohardness,stainless steel,laser ablation in liquid,surface roughness
更新于2025-09-23 15:21:01
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Porosity and joint property of laser-MIG hybrid welding joints for 304 stainless steel
摘要： Laser-metal inert gas (MIG) hybrid butt welding was carried out on 5 mm-thick 304 stainless steel to study the influence of parameters on porosity defect, weld formation, and property of the joints. Research reveals that laser-MIG hybrid welding of 304 stainless steel has porosity sensitivity. The effects of welding speed and laser power on porosity and formation of welds were analyzed. Results show that increasing of laser power and decreasing of welding speed are conducive to improve the formation of welds and reduce porosity. Improving the welding speed on the premise of ensuring proper weld formation is of considerable significance, which is recommended to be 1.8 m/min. Based on the fixed welding speed, parameter of laser power optimization is carried out. Results show that tensile strength and elongation of the welded joints reach at least 98.1% and 75.8% of the base metal when laser powers are 4.3 and 5.0 kW. Compared with real-time monitoring and the numerical simulation method, this kind of results-oriented optimization parameter method has engineering guiding significance.
关键词： property,welding parameter,weld formation,304 stainless steel,porosity,laser-MIG hybrid weld
更新于2025-09-23 15:21:01
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Young’s modulus and fatigue investigation of aluminum nitride films deposited on 304 stainless steel foils using micro-fabricated cantilevers
摘要： Aluminum nitride based (AlN-based) piezoelectric vibration energy harvesters (PVEHs) have been received much attention in the power generation for the device in microelectromechanical systems (MEMS). During the long-time vibration, PVEHs are suffering cyclically dynamic stress. This may result in the defect of the materials, and finally cause the failure of the device. To achieve a reliable design of the device that can work for a long time without failure, the investigation on the mechanical properties of Young’s modulus and fatigue were conducted for AlN films deposited on 304 stainless steel (SUS 304) foils in this study. Two kinds of materials were tested, SUS 304 foils with a thickness of 50 μm (SUS 304 (50 μm)) and a composite material of AlN films deposited on both sides of SUS 304 foils (AlN (1 μm)/ SUS 304 (50 μm)/ AlN (1 μm) structure). The samples were micro-fabricated to cantilevers. Young’s modulus was measured by the micro-cantilever resonance method. The resonant bending fatigue testing method was used to investigate the fatigue properties of the materials. The displacement amplitude of the samples was recorded during the tests. A new criterion by using the change of amplitude versus number of cycles was proposed to define the fatigue life. As results, the Young’s modulus was 184.9 and 342.9 MPa, for SUS 304 foil and AlN film, respectively. Stress-cycle (S-N) curves were plotted by using the proposed criterion successfully. The fatigue strength of SUS 304 foils and the material with AlN/ SUS 304/ AlN structure was estimated to be 294 and 327 MPa, respectively. Fatigue failures of stable crack, intrusions and extrusions, and slip bands, appeared on the surface of SUS 304 foils after the long time vibration. No fatigue failure or surface defect was observed on AlN films.
关键词： 304 stainless steel foil,aluminum nitride film,Young’s modulus,fatigue,micro-fabricated cantilever
更新于2025-09-23 15:21:01
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Graphite Supported Stainless-Steel Electrode for the Degradation of Azo Dye Orange G by Fenton Reactions: Effect of Photo-Irradiation
摘要： An electrode, stainless steel supported on graphite, was used for the degradation of hazardous organic compounds, azo dye Orange G (OG), using the photoelectro- Fenton (PEF) process. Results showed that the applied current controlled the electrogeneration rate of both ferrous ion and hydrogen peroxide, which in turn affected the dye degradation kinetics. At an applied current density of 45 μA cm?2, the SS-graphite electrode yielded a molar ?H2O2(cid:2)=?Fe2t(cid:2) ratio of 3.6, which was optimal for dye degradation. Under otherwise identical conditions, UV irradiation significantly enhanced OG degradation, i.e., PEF is more effective than electro-Fenton (EF) process. At the optimal applied current density of 45 μA cm?2, or optimal molar ?H2O2(cid:2)=?Fe2t(cid:2) of 3.6, OG decolorization and total organic carbon removal were 83% (in 3 h) and 55% (in 7 h), versus 75% (in 3 h) and 20% (in 7 h) by PEF and EF, respectively. OG degradation by both PEF and EF processes followed the pseudo first-order kinetics, which suggested the major role of OH radical in OG decolorization.
关键词： Stainless steel,Graphite,Orange G,Photo-electro-Fenton (FEF),Steady-state approximation,Decolorization
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO? 2015: 34th International Congress on Laser Materials Processing, Laser Microprocessing and Nanomanufacturing - Atlanta, Georgia, USA (October 18–22, 2015)] International Congress on Applications of Lasers & Electro-Optics - Microstructural effects induced by laser shock peening for mitigation of stress corrosion cracking
摘要： Stress corrosion cracking is a phenomenon that can lead to rapid, sudden failure of metallic products. In this paper we examine the mechanisms of SCC mitigation of stainless steel and brass samples using laser shock peening (LSP). The behavior of hydrogen within the crystal lattice is one of the most dominant contributors to SCC, where uptake of hydrogen strains the lattice and increases its hardness. Cathodic charging of the metallic samples in 1M sulfuric acid was performed in order to accelerate hydrogen uptake. Non-treated samples underwent hardness increases of 28%, but LSP treated samples only increased in the range of 0 to 8%, indicative that LSP keeps hydrogen from permeating into the metal. Mechanical U-bends subjected and MgCl2 environments are analyzed, to determine changes in fracture morphology. Surface chemical effects are addressed via Kelvin Probe Force Microscopy, which is used for finding changes in the work function caused by LSP treatment. A finite element model of material deformation from U-bending was developed to analyze and compare the induced stresses. With LSP, there is a potential for overprocessing the samples, whereby negative effects refinement, to corrosion martensite formation) can arise. Detection of any martensite phases formed is performed using x-ray diffraction. We find LSP to be beneficial for stainless steel but does not improve brass’s SCC resistance. With our analysis methods we provide a further understanding of the process whereby LSP reduces subsequently highlight SCC for important implementation of the process.
关键词： Brass,Stainless steel,Hydrogen uptake,Stress corrosion cracking,Cathodic charging,Kelvin Probe Force Microscopy,Laser shock peening,Finite element model
更新于2025-09-23 15:21:01
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Laser Powder Bed Fusion of Precipitation-Hardened Martensitic Stainless Steels: A Review
摘要： Martensitic stainless steels are widely used in industries due to their high strength and good corrosion resistance performance. Precipitation-hardened (PH) martensitic stainless steels feature very high strength compared with other stainless steels, around 3-4 times the strength of austenitic stainless steels such as 304 and 316. However, the poor workability due to the high strength and hardness induced by precipitation hardening limits the extensive utilization of PH stainless steels as structural components of complex shapes. Laser powder bed fusion (L-PBF) is an attractive additive manufacturing technology, which not only exhibits the advantages of producing complex and precise parts with a short lead time, but also avoids or reduces the subsequent machining process. In this review, the microstructures of martensitic stainless steels in the as-built state, as well as the effects of process parameters, building atmosphere, and heat treatments on the microstructures, are reviewed. Then, the characteristics of defects in the as-built state and the causes are specifically analyzed. Afterward, the effect of process parameters and heat treatment conditions on mechanical properties are summarized and reviewed. Finally, the remaining issues and suggestions on future research on L-PBF of martensitic precipitation-hardened stainless steels are put forward.
关键词： 17–4 stainless steel,heat treatment,microstructure,precipitation-hardened stainless steels,ferrite,selective laser melting,building atmosphere,defects,laser powder bed fusion
更新于2025-09-23 15:19:57
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Distortion and Dilution Behavior for Laser Metal Deposition onto Thin Sheet Metals
摘要： The combination of additive manufacturing and incremental sheet forming offers great flexibility in the manufacture of function-integrated parts. In this study, both processes were carried out by the same CNC machine. This offers the possibility to manufacture large-scale lightweight parts with smaller additive parts on it in one machine and clamping device. Additionally, the process combination can lead to a reduced energy and material consumption for small batch sizes. DC01 sheets are used as a substrate with two different initial conditions. The first condition is as delivered steel sheet and the second is an incrementally formed with a thickness of 0.5 mm. The additive manufacturing was conducted by laser metal deposition (LMD). The powder material is a stainless steel 316 L. A segmentation of the cladding surface was applied and the path strategy of the laser movement was varied simultaneously to analyse the warpage of the thin substrate. It is shown that there is a dependency between the build-up strategies and the melt pool temperature, the thermal distortion, the dilution and the size of the cladding area. A segmentation of the working surface causes a lower melt pool temperature and thermal distortion. The lower melt pool temperature also generates a reduced dilution zone.
关键词： Thermal distortion,Laser metal deposition,Incremental sheet forming,Stainless steel
更新于2025-09-23 15:19:57
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Examination of relationship between Urbach energy and open-circuit voltage deficit of flexible Cu(In,Ga)Se <sub/>2</sub> solar cell for its improved photovoltaic performance
摘要： Flexible Cu(In,Ga)Se2 (CIGSe) solar cells on stainless steel (SUS) substrates are developed. The contribution concentrates on the investigation of the correlation between Urbach energy (EU) and open-circuit voltage deficit (VOC,def). The several CIGSe solar cells on soda-lime glass and SUS substrates with various VOC,def values are fabricated through the variations of [Ga]/([Ga]+[In]) ratio (GGI), substrate temperature (TSUB) and Fe concentration of their CIGSe absorbers. The EU is determined based on external quantum efficiency in the long-wavelength edge. It is determined that the EU is influenced by the GGI, TSUB and Fe concentration. The EU is well consistent with the carrier lifetimes and can be an indicator of the CIGSe quality. In addition, the relationship between EU and VOC,def is obviously observed, where the decrease in the EU by 1 meV reduces the VOC,def by 8.6 mV. Through the optimizations of GGI and TSUB as well as the minimization of Fe concentration, the EU is obviously reduced, which implies the improvement of the CIGSe quality. Ultimately, the high η of 17.9% for the flexible CIGSe solar cell on SUS substrate is attained.
关键词： Cu(In,Ga)Se2,stainless steel substrate,TRPL carrier lifetime,Urbach energy,open-circuit voltage deficit
更新于2025-09-23 15:19:57
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Experimental investigation on Ytterbium fiber laser butt welding of Inconel 625 and Duplex stainless steel 2205 thin sheets
摘要： In this study, welding of Superalloy Inconel 625 and duplex stainless steel 2205 (DSS 2205) has been successfully performed through Ytterbium fiber laser at different heat inputs. With decreasing energy input, width of the weld bead narrowed and the mechanical properties of the joint improved. Characterization of the weld joint was carried out using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and micro-hardness testing. No solidification cracks or porosity was observed in the microstructure of the weld metal (WM). Cellular dendritic and columnar dendritic grains were main grain types observed in the weld metal. At heat input of 43 J/mm, inter-dendritic arms of the weld metal witnessed more segregation of Molybdenum and Niobium in comparison of welded samples at heat input of 21.5 J/mm. Carbides of Cr, Mo and Ni are formed in the weld joint interface as revealed by the XRD analysis. Tensile strength study reveals the maximum strength of 890 MPa when the heat supplied is low i.e. 21.5 J/mm. This strength value is more than that of the base metal (DSS 2205). The result obtained in terms of comprehensive structure-property correlation, recommends the effectiveness of laser beam welding for joining of the said dissimilar alloys.
关键词： Mechanical properties,Laser beam welding,Duplex stainless steel 2205,Microstructure,Inconel 625
更新于2025-09-23 15:19:57