316L������ھ�̬Һ̬��еĸ�ʴ��Ϊ�о�

利用脉冲激光诱导击穿光谱仪(LIBS)结合SEM、EDX和维氏硬度(HV)等分析手段,分析了316L不锈钢在350℃的液态锂中静态腐蚀500h后的腐蚀特性.微观形貌分析表明:样品存在较明显的晶间腐蚀,其腐蚀层厚度约为2.7μm.硬度分析表明:腐蚀后表面硬度值约HV234.72,约是腐蚀前硬度值的0.78倍.LIBS组分分析表明:经液态锂腐蚀后的样品表面Ni、Cr等元素含量相对减少;在被腐蚀区域Li元素含量随激光击打深度的增加而减少,而Ni、Cr等元素含量与之近似呈成正比递增;母材区Li元素的渗透深度约3.5μm,约是焊缝区的0.6倍.     

内部爆炸作用下钢箱结构变形规律性实验

箱型结构内部爆炸能够造成比空爆更严重的破坏效果。本文中设计了3个边长600 mm、板厚4 mm的实验试件,并分别用98.4、194.7和355.8 g的TNT炸药进行了内部爆炸实验,得到了所有试件的变形特征。箱体壁板的变形都呈现向外凸出(鼓起)的特点,壁板中心的最终挠度随着爆炸TNT当量的增大而近似成线性增长,拟合了箱体壁板挠厚比与爆炸当量之间的经验公式。通过三维数字图像相关技术,得到了箱体壁板的动态响应过程:爆炸发生后,壁板中心最先产生向外鼓起;壁板中心随后变形增长,同时变形向四周传播;壁板中心变形达到最大值后,板的变形会产生一定量的振荡回缩。     

单个弹丸撞击316L不锈钢引起的变形场

运用金属材料表面纳米化试验机对单个弹丸撞击316L不锈钢表面进行了撞击实验;采用激光共聚焦显微镜观察了弹坑的三维形貌,测量不同振动频率下弹坑的直径及离面位移;采用云纹干涉法对弹坑周围的面内应变场进行测量,并分析振动频率及撞击方式对弹坑尺寸、塑性应变大小以及塑性应变区范围的影响;采用有限元方法对单个弹丸垂直撞击试件表面的应变场进行数值模拟,与实验结果进行比较,分析了弹坑周围残余应力的分布。结果表明:随振动频率的增加,弹坑直径和离面位移都增加,频率在50~55Hz,弹坑直径有突变,离面位移和振动频率呈线性关系;振动频率越大,塑性应变越大,塑性应变分布范围均大于弹坑直径的2倍;同一振动频率下弹丸垂直撞击比倾斜撞击的塑性应变大,而塑性应变分布范围相差不大;面内残余应变场的数值模拟结果和实验结果吻合较好,最大误差小于10%。     

开孔薄壁钢梁-轻骨料混凝土组合楼板火灾后受力性能研究

针对一种由冷弯卷边H型开孔薄壁钢梁和轻骨料混凝土预制板装配而成的新型轻质组合楼板, 对一组两端简支的组合楼板试件开展了烃类火灾作用后的力学性能试验研究. 结果表明, 承担2kN?m-2均布荷载的组合楼板试件在遭受600℃烃类火灾作用后, 仍具有较高的承载能力和整体刚度. 在4kN?m-2的均布荷载作用下, 火灾后损伤最严重的组合楼板试件的跨中挠度仍小于L/400, 且未见混凝土的进一步开裂. 试验结果表明, 薄壁钢梁腹板开孔形式及抗剪键的数量对火灾后组合楼板的整体刚度和受力性能有明显影响, 从提高组合楼板整体刚度的角度考虑, 对主钢梁腹板的开孔宜首选孔径大、数量少的分布形态, 同时适当增加抗剪键数量.     

织构参数对高速钢激光条纹表面磨损量的影响

应用激光加工技术, 在高速钢试件表面制备出条纹织构, 对高速钢条纹织构试件进行了销盘式摩擦磨损试验, 并测试了磨损量. 通过实验, 分析织构参数对高速钢激光加工条纹表面磨损量的影响规律. 通过对数学模型的拟合分析, 确定并建立了高速钢条纹试件表面磨损量的二阶数学模型. 根据该磨损量数学模型, 对条纹参数进行了优化. 研究表明, 织构参数对高速钢条纹表面磨损量的影响程度依次为高度、宽度和间距; 方差分析表明, 所建立的高速钢条纹表面磨损量与织构参数之间的数学模型是显著的. 同时确定了激光织构表面低磨损量的条纹参数取值范围, 得到了优化后的条纹织构参数.     

Kopsia Singapurensis提取物对酸性介质中低碳钢的缓蚀效应(英文)

The influence of the alkaloid extract of Kopsia singapurensis on the corrosion behavior of mild steel (MS) in 1 mol·L-1 HCl and 1 mol·L-1 H2SO4 was studied using electrochemical techniques, viz., potentiodynamic polarization and AC impedance. The experimental results clearly show that the plant extract effectively inhibits corrosion in both acid media and the inhibition efficiency obtained from the electrochemical techniques is in good agreement. Furthermore, the polarization technique indicates that the extract acts as an anodic type inhibitor in HCl and as a mixed type in H2SO4. Scanning electron microscopy (SEM) was carried out to examine the surface morphological changes of metal specimens in both the inhibited and uninhibited solutions. SEM images show the formation of an adsorbed layer over the metal surface by the inhibitor molecule. The presence of alkaloidal constituents in the plant extract was confirmed by Fourier transform infrared (FTIR) spectroscopy and chemical analysis.     

基于光纤光栅绝对测量技术的高耐久智能钢拉杆

针对目前钢拉杆构件缺少施工荷载下的内力测试和服役期间的长期监测手段问题,采用玻璃钢封装技术研制开发出一种新型的基于光纤光栅绝对测量传感技术的高耐久性智能钢拉杆。在理论屈服荷载85%的拉伸荷载下,智能钢拉杆感知的应变具有很好的线性度和重复性,由其得到的测试杆力与实验张拉力吻合良好,误差在4%以内。该智能钢拉杆具有抗电磁干扰、传感距离长、成本低、耐腐蚀、绝对测量等优点,既可以方便给出任何阶段的受力状态,也可以作为一个大应变式荷载传感器对其相邻的结构进行荷载监测,适合用于恶劣服役环境下的钢拉杆工程结构。     

Study of vacancy defects and their thermal stability in MeV Fe ion irradiated RAFM steel using positron beam Doppler broadening spectroscopy

Indian reduced activation ferritic-martensitic steel was irradiated with 1.1?MeV Fe ions to various doses from 1 to100?dpa at room temperature. The depth profiling of irradiation-induced vacancy-type defects and the defect-recovery under post-irradiation annealing was studied using variable low-energy positron beam Doppler broadening spectroscopy. The influence of irradiation-induced defects on the microstructural properties was studied by glancing incidence x-ray diffraction (GIXRD) and nanoindentation technique. Positron annihilation study showed the signatures of reduced vacancy concentration at the peak damage region due to injected interstitial effect from 30 to 100?dpa and the widening of vacancy-interstitial recombination-rich region towards the end of ion range with the increase in dose. The GIXRD results were analysed by modified Williamson–Hall plot method, and the variation of coherent domain size and micro-strain with irradiation dose was studied. Irradiation-induced hardening was observed in the nanoindentation study. The features observed in the GIXRD and nanoindentation study are correlated with the depth-resolved defect distribution observed in the positron annihilation study.     

Grain refinement and strengthening of austenitic stainless steels during large strain cold rolling

The microstructure/texture evolution and strengthening of 316?L-type and 304?L-type austenitic stainless steels during cold rolling were studied. The cold rolling was accompanied by the deformation twinning and micro-shear banding followed by the strain-induced martensitic transformation, leading to nanocrystalline microstructures consisting of flattened austenite and martensite grains. The fraction of ultrafine grains can be expressed by a modified Johnson-Mehl-Avrami-Kolmogorov equation, while inverse exponential function holds as a first approximation between the mean grain size (austenite or martensite) and the total strain. The deformation austenite was characterised by the texture components of Brass, {011}<211>, Goss, {011}<100>, and S, {123}<634>, whereas the deformation martensite exhibited a strong {223}<110> texture component along with remarkable γ-fibre, <111>∥ND, with a maximum at {111}<211>. The grain refinement during cold rolling led to substantial strengthening, which could be expressed by a summation of the austenite and martensite strengthening contributions.     

Facile preparation of superhydrophilic and underwater superoleophobic mesh for oil/water separation in harsh environments

An effective solution to separate oil and water is urgently needed owing to the increasingly serious problem of oil pollution. Numerous studies have been done to endow ordinary materials with extreme wettability for oil/water separation. Unfortunately, most of these materials cannot work in harsh environments, resulting in the low stability and practicability in practice. Herein, a facile method was proposed to fabricate superhydrophilic and underwater superoleophobic mesh by immersing ordinary mesh in a mixture of sulfuric acid (H₂SO₄) and chromium trioxide (CrO₃). After immersing for just 1?min, the mesh was endowed with superhydrophilicity (CA?=?0°) and underwater superoleophobicity (hexane CA?=?151°, SA?=?14°). Increasing the immersion time to 3?min, the prepared mesh exhibited better superoleophobicity. A separation device was developed based on the prepared mesh and the separation efficiencies for diverse oil/water mixtures containing acid, alkaline, salt and hot water were above 95%. The device retained a high efficiency after being reused for 20 times and the prepared mesh maintained superoleophobicity after immersing underwater for 72?h and abrasion test of 100 cycles. This oil/water separation method is easy-to-use, inexpensive, power-free and it can be used to separate caustic oil/water mixtures.