电感耦合等离子体原子发射光谱法测定不锈钢中8种合金元素

采用硝酸-盐酸-水(1+3+6)混合酸溶液溶解不锈钢样品,用电感耦合等离子体原子发射光谱法同时测定试样溶液中铬、镍、铜、锰、磷、硅、钼和钛等8种合金元素。选择钇元素作为内标元素,选择波长为357.869,231.604,327.396,257.610,178.284,251.611,202.030,337.280 nm8条谱线依次作为铬、镍、铜、锰、磷、硅、钼和钛的分析线。方法用于分析了12种标准物质,测定值同证书值一致,各元素的相对标准偏差(n=7)均小于5.5%。     

铜(Ⅱ)-硫氰酸盐-乙基紫-微乳液分光光度法测定钢样中的微量铜

在非离子型微乳液(OP/n-C5H11OH/n-C7H16/H2O)存在下,Cu2+与硫氰酸盐形成络阴离子[Cu(SCN)4]2-,在pH 3.6乙酸盐缓冲溶液中,该络阴离子再与乙基紫(EV)形成吸附型离子络合物,该络合物的组成为[Cu(SCN)4]2-:EV=1:2,最大吸收波长为660nm,表观摩尔吸光系数ε660为1.08×l05L.mol-1.cm-1,Cu2+含量在1.7～18.0μg/50 mL范围内符合比尔定律,检出限为0.5μg/50 mL,用该方法测定了钢中的铜,相对标准偏差小于2%。     

氯化硝基四氮唑蓝对钢在盐酸溶液中的缓蚀作用

采用失重法、动电位极化曲线、电化学阻抗谱(EIS)和扫描电子显微镜(SEM)研究了氯化硝基四氮唑蓝(NTBC)在1.0-5.0mo·lL-1HCl溶液中对冷轧钢(CRS)的缓蚀作用.结果表明:NTBC在1.0mo·lL-1HCl溶液中对冷轧钢具有良好的缓蚀作用,且在钢表面的吸附符合Langmuir吸附等温式.缓蚀率随缓蚀剂浓度的增加而增大,但随盐酸浓度和温度的增加而减小.求出了相应的吸附热力学(吸附自由能ΔG0,吸附焓ΔH0,吸附熵ΔS0)和腐蚀动力学参数(腐蚀速率常数k,动力学常数B),并根据这些参数讨论了缓蚀作用机理.动电位极化曲线表明:NTBC为混合抑制型缓蚀剂;EIS谱在高频区呈容抗弧,在低频区出现感抗弧,电荷转移电阻随缓蚀剂浓度的增加而增大.SEM再次表明NTBC对钢在盐酸介质中的腐蚀产生了明显的抑制作用.     

A three dimensional approach to model steel wire ropes used in high energy absorber apparatus

The modeling method and dynamical characteristics of steel wire ropes has been researched for several decades. In the past, steel wire ropes were usually modeled as a two dimensional system, which was only suitable for the planar motion. Also, no kink-wave propagation was considered when steel wire ropes were used in relatively low speed engineering application areas. By contrast, a three dimensional approach to model steel wire ropes used in high energy absorber apparatus is presented in this paper. Three dimensional contacts between steel wire ropes and other objects and kink-wave propagation in steel wire ropes are taken into consideration when applying the new approach to model steel wire ropes. Compared to the two dimensional model of steel wire ropes, the proposed model regards steel wire ropes as a multi-body system consisting of identical cylindrical elements with 6 degrees of freedom connected by space constraints. Impact forces generated by three dimensional contacts between steel wire ropes and other objects are calculated and theories of elastic wave propagation are applied to analyze the kink-wave propagation when steel wire ropes are loaded with a sudden perpendicular impact by a high speed moving object. In addition, mathematical model of steel wire ropes is established and numerical simulation of the three dimensional model of steel wire ropes is implemented. By comparing the simulation results with the experimental data available, the model of steel wire ropes proposed in this paper is demonstrated to be valid and correct. Therefore, the proposed modeling method can be treated as a new approach in the research field of modeling steel wire ropes. The dynamical characteristics of the steel wire ropes based on this new modeling approach are addressed simultaneously and plots of the dynamics of steel wire ropes cannot only be regarded as a basis for the further comparative studies, but also can provide some significant and interesting results.     

Dimensionado en compresión en acero: el peso del pandeo

The verification of the slender compressed members of a structure is a well formulated and codified problem. However, the non-linearity of the design process, combined with the no linearity of the physical problem requires an iterative process to define the piece that solves a given problem. This paper demonstrates an identity relationship between seemingly different problems, based on which we develop a theoretical approach and a simple procedure to determine, without iteration and with little margin for error, the piece needed for a given problem. The paper provides a statistical model to check that the provided procedure is safe and effective in the 98% of the problems in buildings —pillars and bars from trusses—. The presented approach therefore greatly facilitates decisions in this area.     

4 GPa压力处理对T8钢在加热过程中固态相变动力学的影响

本文通过差示扫描量热分析(DSC)法测试了经4 GPa压力处理前后, T8钢在加热过程中固态相变温度和转变时间,计算其相变激活能和Avrami指数, 并结合金相组织观察, 探讨了4 GPa压力处理对T8钢在加热过程中固态相变动力学的影响.结果表明: 4 GPa压力处理能使T8钢组织中形成奥氏体的温度向低温移动, 相变时间和Avrami指数减小, 相变激活能增大, 有利于形成尺寸细小的晶粒, 但对其相变机理的影响不大.     

Inhibition of initial surface oxidation by strongly bound hydroxyl species and Cr segregation: H2O and O2 adsorption on Fe-17Cr

The initial stages of surface oxidation of Fe-17Cr (ferritic stainless steel) were investigated at 323 K by X-ray photoelectron spectroscopy (XPS) and inelastic electron background analysis. The results indicated the formation of a mixed iron-chromium oxide layer upon O₂ exposure and the formation of a thin chromium oxyhydroxide layer upon H₂O exposure. The oxidation of Fe did not occur in the latter case. Moreover, it was found that pre-exposing the Fe-17Cr surface to H₂O significantly hinders subsequent oxidation by O₂, thus providing a way to control the formation of nanoscale oxides on stainless steel materials. It was concluded that the formation of strongly bound hydroxyl species together with adsorbate-induced segregation of Cr severely limits the reaction between O₂/H₂O and Fe from the alloy.     

直读光谱仪分析不锈钢中氮

直读光谱分析不锈钢中氮含量 ,确定了氮的光谱分析线、最佳分析条件 ,分析样品的制备要求 ,共存元素的影响和氮校准曲线的拟合情况。本法具有良好的准确度和精密度 ,氮元素的分析检出限为6 .3μg/ g,检测范围为 0 .0 0 1%— 0 .4 2 %。     

ARL-4460金属分析仪测定低合金钢中微量五害元素

应用瑞士 ARL- 446 0金属分析仪 (真空光电直读光谱仪 ) ,测定了石油管材 (低合金钢 )中的微量五害元素 (Pb、Sn、As、Sb、Bi)含量 ,优化了分析条件 ,讨论了分析结果和影响因素 ,确定了方法的检出限。本方法具有操作简便、准确度较高、成本低等优点 ,用于炉前快速分析与管材检验 ,取得了满意的效果。     

A simplified model for nonlinear dynamic analysis of steel column subjected to impact

This paper presents a new simplified model of the nonlinear dynamic behavior of a steel column subjected to impact loading. In this model, the impacted column, which undergoes large displacement, consists of two rigid bars connected by generalized elastic–plastic hinges where the deformation of the entire steel column as well as the connections is concentrated. The effect of the rest of the structure on the column is modeled by an elastic spring and a point masse both attached to the top end of the column which is also loaded by a compressive force. The plastification of the hinges follows the normality rule with a yield surface that accounts for the interaction between M and N. The latter is described by a super-elliptic yield surface that allows ones to consider a wide range of convex yield criterion by simply varying the roundness factor that affects the shape of the limit surface. By including these features, the model captures both geometry and material nonlinearities. Both the flow rule and the equations of motion are integrated using the midpoint scheme that conserves energy. The non-smooth nature of impact is considered by writing the equations of motion of colliding masses using differential measures. Contact conditions are written in terms of velocity and combined with Newton's law to provide the constitutive law describing interactions between masses during impact. Numerical applications show that the model is able to capture the behavior of a column subjected to impact.