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Process improvement in laser hot wire cladding for martensitic stainless steel based on the Taguchi method

Zilin HUANG,Gang WANG,Shaopeng WEI,Changhong LI,Yiming RONG

《机械工程前沿（英文）》 2016年第11卷第3期页码 242-249 doi: 10.1007/s11465-016-0397-7

摘要：

Laser hot wire cladding, with the prominent features of low heat input, high energy efficiency, and high precision, is widely used for remanufacturing metal parts. The cladding process, however, needs to be improved by using a quantitative method. In this work, volumetric defect ratio was proposed as the criterion to describe the integrity of forming quality for cladding layers. Laser deposition experiments with FV520B, one of martensitic stainless steels, were designed by using the Taguchi method. Four process variables, namely, laser power (P), scanning speed (V_s), wire feed rate (V_f), and wire current (I), were optimized based on the analysis of signal-to-noise (S/N) ratio. Metallurgic observation of cladding layer was conducted to compare the forming quality and to validate the analysis method. A stable and continuous process with the optimum parameter combination produced uniform microstructure with minimal defects and cracks, which resulted in a good metallurgical bonding interface.

关键词： process optimization Taguchi method signal-to-noise (S/N) ratio volumetric defect ratio laser hot wire cladding

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Hybrid forming mechanism of patternless casting and laser cladding

Zhongde SHAN, Fuzhen SUN, Yang LIU

《机械工程前沿（英文）》 2019年第14卷第4期页码 393-401 doi: 10.1007/s11465-019-0550-1

摘要： In accordance with the requirement of manufacturing dies quickly and economically, a hybrid forming method of stamping dies for automobile panels is proposed. The method combines digital patternless casting and high-power laser cladding. An experimental study is conducted on the hybrid forming process and its trial production and application in the manufacturing of stamping dies for typical panels. Results prove that the laser cladding layer exceeds HRC60 (Rockwell hardness) and thus meets the production efficiency requirement of automobile dies. The rate of defects is well controlled. Compared with traditional technology, this technology has remarkable advantages and advancement.

关键词： patternless casting laser cladding hybrid forming rapid tooling

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激光表面改性技术发展研究

张群莉,王梁,梅雪松,姚建华

《中国工程科学》 2020年第22卷第3期页码 71-77 doi: 10.15302/J-SSCAE-2020.03.010

摘要：

激光表面改性技术利用高能量密度的激光束对零部件局部易损易耗区域进行快速处理，获得材料表面所需性能，进而大幅延长零部件使用寿命，已在航空航天、石油化工、能源、交通、冶金等领域获得应用。本文针对激光冲击强化、激光淬火、激光熔覆3 种典型的激光表面改性技术，梳理了相应技术特点及国内外应用现状，凝练我国相关技术领域面临的差距与问题，总结激光表面改性技术的重点发展方向：专用合金材料制备、多能场激光复合表面改性、面向现场的激光再制造、激光冲击强化控形控性、激光表面改性智能化、激光表面微结构化。从政府引导、国产化创新、产业链完善、质量评价标准体系、人才培养等方面提出发展建议，以期为我国激光表面改性技术发展提供参考借鉴。

关键词：激光表面改性冲击强化淬火熔覆发展趋势

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Modification of premixed combustion in shear layers by grid turbulence

MU Kejin, WANG Yue, ZHANG Zhedian, NIE Chaoqun

《能源前沿（英文）》 2007年第1卷第2期页码 245-250 doi: 10.1007/s11708-007-0034-6

摘要： The influence of grid turbulence on the shear layer of a jet and the premixed flames embedded in it was investigated in the present study. The velocity field of the jet was measured by using hot-wire anemometry. It was found that grid turbulence reduced turbulence intensities in the shear layer and suppressed low frequency fluctuation. Moreover, the energy contained in small-scale fluctuation was increased and turbulence became homogeneous. The results indicate that grid turbulence inhibits the formation of a large-scale coherent structure in the shear layer. Flame temperature was measured by using a compensated fine-wire thermocouple. It was found that grid turbulence reduced low frequency fluctuation of the flame fronts, increased the small-scale wrinkles and elevated the mean temperature of the flame zone. The results show that grid turbulence can enhance and stabilize premixed flames in shear flow.

关键词： homogeneous fine-wire thermocouple temperature hot-wire anemometry premixed

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The Application and the Prospect of Remanufacturing Technologies in the Metallurgical Industry

Jie Xiong,Jian-cheng Fan,Jv Yuan

《工程管理前沿（英文）》 2016年第3卷第2期页码 165-170 doi: 10.15302/J-FEM-2016023

摘要： Metallurgical equipment is subjected to severe working conditions and the components suffer from various types of physical damages such as abrasion, corrosion and crack. Advanced surface engineering technologies and resistant coatings on the damaged surface can improve surface properties, extend service lives, reduce maintenance costs and improve product quality in the metallurgical industry. This paper introduces remanufacturing technologies, including electroplating, overlaying welding, thermal spraying and laser surface cladding and their applications in the metallurgical industry, and analyzes the development tendency and prospect of remanufacturing technologies.

关键词： remanufacturing technology electroplating overlaying welding thermal spraying laser surface cladding

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激光熔覆NiCrAl-陶瓷涂层的显微组织研究

陈庆华,魏仑,龙晋明,李俊昌

《中国工程科学》 2001年第3卷第10期页码 64-71

摘要：

运用激光熔覆技术在40Cr钢表面制备了(TiO₂+B₂O₃+Al₂O₃+TiB₂)/NiCrAl金属陶瓷涂层，其中的TiB₂和Al₂O₃陶瓷颗粒在激光加工过程中原位反应生成；对熔覆层的组织、物相、元素分布和显微硬度分布特征进行了分析研究；熔覆层中的主相依次分别是γ-Ni,γ′,Al₂O₃和TiB₂，熔覆层的微观结构和硬度主要和激光处理参数和熔覆层化学组成有关^［1～9］；陶瓷相的原位生成和加入，大大改善了熔覆层的硬度和覆层/基体界面的结合性能。

关键词：激光熔覆金属陶瓷微观组织物相显微硬度

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Influence of the field humiture environment on the mechanical properties of 316L stainless steel repaired with Fe314

Lianzhong ZHANG, Dichen LI, Shenping YAN, Ruidong XIE, Hongliang QU

《机械工程前沿（英文）》 2018年第13卷第4期页码 513-519 doi: 10.1007/s11465-018-0503-0

摘要：

The mechanical properties of 316L stainless steel repaired with Fe314 under different temperatures and humidities without inert gas protection were studied. Results indicated favorable compatibility between Fe314 and 316L stainless steel. The average yield strength, tensile strength, and sectional contraction percentage were higher in repaired samples than in 316L stainless steel, whereas the elongation rate was slightly lower. The different conditions of humiture environment on the repair sample exerted minimal influence on tensile and yield strengths. The Fe314 cladding layer was mainly composed of equiaxed grains and mixed with randomly oriented columnar crystal and tiny pores or impurities in the tissue. Results indicated that the hardness value of Fe314 cladding layer under different humiture environments ranged within 419–451.1 HV_0.2. The field humiture environment also showed minimal impact on the average hardness of Fe314 cladding layers. Furthermore, 316L stainless steel can be repaired through laser cladding by using Fe314 powder without inert gas protection under different temperatures and humidity environments.

关键词： laser cladding repaired performance tensile strength temperature and humidity environment

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Elevated temperature creep model of parallel wire strands

《结构与土木工程前沿（英文）》页码 1060-1071 doi: 10.1007/s11709-023-0981-y

摘要： Parallel wire strands (PWSs), which are widely used in prestressed steel structures, are typically in high-stress states. Under fire conditions, significant creep effects occur, reducing the prestress and influencing the mechanical behavior of PWSs. As there is no existing approach to analyze their creep behavior, this study experimentally investigated the elevated temperature creep model of PWSs. A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test. It was concluded that the temperature level had a more significant effect on the creep strain than the stress level, and 450 °C was the key segment point where the creep rate varied significantly. By comparing the elevated temperature creep test results for PWSs and steel strands, it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels. The parameters in the general empirical formula, the Bailey–Norton model, and the composite time-hardening model were fitted based on the experimental results. By evaluating the accuracy and form of the models, the composite time-hardening model, which can simultaneously consider temperature, stress, and time, is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.

关键词： parallel wire strands experimental study elevated temperature creep model

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Preconcentration of trace elements by adsorption onto a niobium wire for electrothermal atomization atomic

Satoshi KANECO, Hiroaki KITANAGA, Hideyuki KATSUMATA, Tohru SUZUKI

《化学科学与工程前沿（英文）》 2012年第6卷第4期页码 432-435 doi: 10.1007/s11705-012-1219-z

摘要： In the present work, a new preconcentration method of trace elements by adsorption onto a niobium wire has been developed for electrothermal atomization atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer. Detection limits (pg·mL ) by this method combined with ETAAS were 45 for bismuth, 7.0 for cadmium, 20 for copper, 1.3 for gold, 36 for lead, 65 for manganese, 9.5 for rhodium and 19 for silver.

关键词： preconcentration adsorption onto niobium wire electrothermal atomization atomic absorption spectrometry tungsten tube atomizer trace elements

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Construction of nitrogen-doped carbon cladding LiMnO film electrode with enhanced stability for electrochemically

《化学科学与工程前沿（英文）》 2023年第17卷第12期页码 2050-2060 doi: 10.1007/s11705-023-2343-7

摘要： Reducing the dissolution of Mn from LiMn₂O₄ (LMO) and enhancing the stability of film electrodes are critical and challenging for Li⁺ ions selective extraction via electrochemically switched ion exchange technology. In this work, we prepared a nitrogen-doped carbon cladding LMO (C-N@LMO) by polymerization of polypyrrole and high-temperature annealing in the N₂ gas to achieve the above purpose. The modified C-N@LMO film electrode exhibited lower Mn dissolution and better cyclic stability than the LMO film electrode. The dissolution ratio of Mn from the C-N@LMO film electrode decreased by 42% compared to the LMO film electrode after 10 cycles. The cladding layer not only acted as a protective layer but also functioned as a conductive shell, accelerating the migration rate of Li⁺ ions. The intercalation equilibrium time of the C-N@LMO film electrode reached within an hour during the extraction of Li⁺ ions, which was 33% less compared to the pure LMO film electrode. Meanwhile, the C-N@LMO film electrode retained evident selectivity toward Li⁺ ions, and the separation factor was 118.38 for Li⁺ toward Mg²⁺ in simulated brine. Therefore, the C-N@LMO film electrode would be a promising candidate for the recovery of Li⁺ ions from salt lakes.

关键词： LiMn₂O₄ lithium extraction surface coating cyclic stability Mn dissolution

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Numerical studies of dynamic behavior of liquid film on single-layer wire mesh with different wettabilities

《化学科学与工程前沿（英文）》页码 1672-1680 doi: 10.1007/s11705-022-2205-8

摘要： Droplet impacting on the stainless steel wire mesh is very common in chemical devices, like a rotating packed bed. Surface wettability of wire mesh significantly affects the liquid flow pattern and liquid dispersion performance. However, the effect of surface wettability on the impaction phenomena at microscale such as liquid film is still unknown. In this work, the dynamic behavior of liquid film on the surface of wire mesh was analyzed by computational fluid dynamics simulation. The dynamic behavior of liquid film on the surface of wire mesh can be divided into the following three steps: (1) spreading step; (2) shrinkage process; (3) stabilizing or disappearing step. Effects of surface wettability, as well as operating conditions, on wetting area and liquid film thickness were studied. Compared to the hydrophilic wire mesh, the final wetting area of hydrophobic wire mesh is zero in most cases. The average liquid film thickness on the surface of hydrophilic wire mesh is 30.02–77.29 μm, and that of hydrophobic wire mesh is 41.76–237.37 μm. This work provided a basic understanding of liquid film flow at microscale on the surface with various surface wettabilities, which can be guiding the packing optimization and design.

关键词： stainless steel wire mesh computational fluid dynamics surface wettability liquid film impacting

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A hot future for cool materials

《能源前沿（英文）》 2023年第17卷第4期页码 447-449 doi: 10.1007/s11708-022-0854-4

摘要： The widespread need to pump heat necessitates improvements that will increase energy efficiency and, more generally, reduce environmental impact. As discussed at the recent Calorics 2022 Conference, heat-pump devices based on caloric materials offer an intriguing alternative to gas combustion and vapor compression.

关键词： magnetocaloric electrocaloric mechanocaloric elastocaloric barocaloric

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Experimental study on wire breakage detection by acoustic emission

Limin SUN, Ji QIAN

《结构与土木工程前沿（英文）》 2011年第5卷第4期页码 503-509 doi: 10.1007/s11709-011-0132-8

摘要： This paper experimentally investigated wire breakage detection in a steel cable by acoustic emission (AE) waveform. In the experiments, the attenuation laws of waveform amplitudes were discussed based on stress wave propagation in the wire, which was generated by kNocking and wire breakage. Then the wave velocity was calculated based on the reach time of the stress wave from each sensor. Finally, based on the waveform attenuation laws and the linear position method, the amplitude and energy of the source were confirmed through the measured waveform to identify the source category. The experimental results illustrated that the stress wave from different sources has a different frequency spectrum, and the amplitude attenuation factor varied with the stress wave frequency; high frequency waves had a greater attenuation factor. Compared with the other source, the wire breakage source contained a much higher energy, and thus, the wire breakage signal can be distinguished from the other source by comparing the non-attenuation energy at the source position.

关键词： acoustic emission (AE) waveform wire breakage attenuation factor wave velocity

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游离磨料多股线线锯切割实验研究

王金生,姚春燕,彭伟,金鑫, 陈世杰

《中国工程科学》 2012年第14卷第11期页码 94-98

摘要：

游离磨料线锯切割是将磨浆中的磨粒通过一定速度的细钢丝线带入切割区域，达到去除工件材料的目的。多股线由多根细金属线绕制而成，表面具有很多凹槽，与钢丝线光滑表面相比，可以输送更多的磨粒进入切割区域，从而提高切割效率。应用0.25 mm的多股线和0.25 mm的钢丝线对光学玻璃K9进行切割对比实验，结果表明，在相同工艺条件下，多股线的切割效率和表面粗糙度均优于钢丝线，但切缝宽度大于钢丝线。

关键词：线锯游离磨料加工切割效率

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evaluation methodology for masonry building and retrofitting using splint and bandage technique with wire

Pravin Kumar Venkat Rao PADALU; Yogendra SINGH

《结构与土木工程前沿（英文）》 2022年第16卷第4期页码 478-505 doi: 10.1007/s11709-022-0817-1

摘要： The paper presents a seismic safety assessment of unreinforced masonry (URM) building using two approaches. The first approach uses the ‘Pier Analysis’ method, based on the concept of equivalent lateral stiffness, where in-plane and out-of-plane actions are considered independently. The second approach is developed with the program SAP2000, where the linear response is evaluated using continuum ‘finite element modelling’ (FEM). Both methods are compared to evaluate the safety of wall piers and the differences in the outcomes under combined gravitational and lateral seismic forces. The analysis results showed that few wall elements are unsafe in in-plane and out-of-plane tension. It is also observed that the pier analysis method is conservative compared to FEM, but can be used as a simplified and quick tool in design offices for safety assessment, with reasonable accuracy. To safeguard the URM wall piers under lateral loads, a retrofitting technique is adopted by providing vertical and horizontal belts called splints and bandages, respectively, using welded wire mesh (WWM) reinforcement. The study using the ‘Pier Analysis’ shows that the lateral load capacity of unsafe URM piers can be enhanced up to 3.67 times and made safe using the applied retrofitting technique. Further, the retrofitting design methodology and recommendations for application procedures to on-site URM buildings are discussed in detail.

关键词： unreinforced masonry seismic in-plane and out-of-plane forces pier analysis finite element modelling splint and bandage technique with wire mesh