钢中超低硫(<5μg/g)光谱与红外分析方法的研究

我国宽厚板冶炼钢种的硫成分一般小于5μg/g.为从时间上保证炉前、钢包、精炼冶炼过程成分的调控,需要采用光谱分析技术来检测这些过程的成分,而冶炼的成品试样则采用红外碳硫分析技术保证分析的精度.通过研究使冶炼的过程中的炉前、钢包、精炼试样全部采用光谱分析,成品试样能够在红外分析仪上检测.光谱仪分析超低硫的分析精度在1.5μg/g以下,红外分析仪分析超低硫的分析精度在0.4μg/g以下.     

脉冲熔融-惰气保护红外法测钛铁中氧含量

采用Leco公司ON836脉冲加热惰气熔融红外线吸收法测定Ti70钛铁中氧含量，分别对分析功率、称样量、助熔剂、比较器水平与分析时间、检出限、标准曲线的建立进行了研究。通过正交试验确定分析的最佳条件，研究表明，称样量0.07～0.09 g,采用镍蓝-锡囊为助熔剂，分析功率为4.5 kW,分析积分时间为40 s时结果稳定可靠。采用2个钒铁标准样品建立的氧校正曲线，相关系数大于0.999;在最佳分析条件下对钛铁样品中氧进行了5次平行测定，分析样品的相对标准偏差均在5%以下，采用钒铁标准样品进行加标回收试验，回收率为97%～106%。本方法简便、快速、准确，在实际应用中取得了比较满意的结果。     

硅铁中锰铬磷三元素的连续快速测定

硅铁中锰、铬、磷的分析,锰常采用过硫酸铵氧化光度法,铬常采用Na_2CO_3分离,二苯卡巴肼光度法;磷常采用重量法或铋磷钼蓝光度法。为了解决三元素连续测定问题,我们在同一份样品试液中进行试验,并改进了Mn、Cr、P的分析,现在Mn     

普通电解槽超低温生产节能技术

文章重点介绍了普通铝电解槽超低温生产节能工艺技术采用的技术策略,对低电压、超低温度、强化电流与富含Li、K、Ca等元素的电解质体系熔体进行了分析,指出电解铝厂采用此技术的疑难点并给出了解决疑难点的措施。通过在已采用低电压节能技术的200kA普通平底铝电解槽上的应用实践及主要技术参数与经济技术指标在应用前后的对比分析,证明了此工艺技术的节能效果。     

安钢RH精炼工艺中的质谱炉气分析系统

对于高品质钢的冶炼,RH真空循环脱气工艺功能强大,技术效益显著,目前在国内的应用越来越普遍。采用质谱炉气分析系统在线分析RH工艺过程气体成分,结合流量、温度测控技术,可以实现对RH工艺的过程优化和终点控制。本文介绍了在安钢第二炼轧厂RH工艺中采用的质谱炉气分析系统,包括其组成、安装布局、分析性能和在现场的工作模式等。采用吹氧脱碳处理工艺、不吹氧脱碳处理工艺和脱气处理工艺对炉气分析系统进行测试表明：该系统能够实时、连续和准确地反映处理过程中各成分随时间的变化;60米采样距离,系统总滞后时间小于40s;炉气成分变化过程同处理工艺完全吻合。可预见采用炉气分析技术,可为RH精炼工艺的终点控制及工艺的实时调整提供判据,从而缩短RH冶炼时间,提升冶炼品质。     

强夯地基处理对下伏引水工程隧洞影响研究

某机场跑道与下伏引水工程隧洞在同一平面位置不同高程交叉.文章采用二维、三维模拟,在引水工程隧洞先行建设条件下,机场采用强夯法进行填土地基处理,模拟分析研究3000kN?m夯击夯击作用的二维应力应变、夯击作川下的水平影响范围及4000kN?m夯击施工、双夯击叠加效应等,并根据分析研究成果提出机场采用强夯进行地基处理的安全...     

小方坯连铸20CrMnTiH齿轮钢宏观偏析控制

针对小方坯连铸齿轮钢偏析严重的问题,采用化学元素分析以及原位分析仪分析了断面碳元素的分布情况,通过低过热度、拉速、电磁搅拌以及二冷水试验,确定了最佳连铸工艺参数。工业应用试验表明,过热度采用20℃±5℃,拉速采用1.30 m/min,结晶器电磁搅拌和凝固末端电磁搅拌的电流强度分别采用250 A和50 A,二冷水比水量采用0.41L/kg有利于偏析控制,铸坯断面碳偏析指数控制在0.94～1.05,棒材断面硬度(HV)控制在±10以内。     

冷轧辊镀铬层有限元分析

针对冷轧辊在轧制过程中磨损和剥落,提出采用在轧辊表面镀铬的方法来解决这一问题.采用弹塑性有限元法建立了三维非对称轧制有限元模型.利用该模型分析了冷轧过程中轧辊在不同的镀层硬度、厚度、层数下的应力情况.通过分析模拟的结果来制定比较优化的镀铬层的状态.     

光度法同时测定硅铁中锰和铬

钢铁冶炼使用的硅铁中锰、铬的测定,一般采用滴定法或光度法等分别测定。为了提高分析速度,降低分析检验成本,提高经济效益,本文在参阅有关文献资料的基础上,通过研究试验,采用等吸收点法于普通分光光度计上用同一份显色溶液,同时测定锰和铬,分析结果快速、准确,可应用于各种牌号硅铁中锰、铬的测定。     

X射线荧光光谱法分析高碳铬镍生铁中7种元素

高碳铬镍生铁是不锈钢冶炼的前期产品,该钢中C、Si、Cr、Ni含量高,高含量元素间的谱线干扰给样品分析的准确度带来较大影响,提高该钢中主元素分析的准确度是降低不锈钢冶炼成本的关键。实验通过铣床参数的组合优化,确定了样品表面制备的最佳参数。通过X射线荧光光谱法分析条件的优化,确定了在40 kV电压和70 mA电流下,Si、Cr、Ni使用固定道分析谱线,C、Mn、P、S使用Kα1,2扫描道分析谱线;C使用AX16C晶体,Si使用InSb晶体,P和S使用Ge111晶体,Mn、Cr、Ni使用LiF200晶体;同时C使用2.60°超粗准直器,其他元素使用0.25°中粗准直器;在4~6 s时间内进行分析的试验条件。使用标准样品对C、Ni采用浓度乘法校正,对Si采用强度加法校正,对S采用浓度加法校正,对Mn、P、Cr采用强度乘法校正,绘制了C、Si、Mn、P、S、Cr、Ni 7个主元素的分析曲线,各曲线回归的相关系数在0.996 7~0.999 9之间。对实验方法进行了长期和短期精密度验证,分析结果的相对标准偏差(RSD,n=11)在0.019%～2.0%之间。正确度试验显示:样品的分析结果与参考值吻合较好。对日常分析中,时常出现的手指接触分析面,或是在样品表面被污染时用乙醇清洁的情况进行了试验比对,给出只有在不关注C元素分析结果时,才能对样品表面进行乙醇清洁处理。实验方法用于高碳铬镍生铁的分析可提高准确度,降低不锈钢冶炼成本。     

Localized Buckling of a Bilinear Elastic Ring under External Pressure

A fully nonlinear finite element analysis for prediction of localization in moderately thick imperfect rings under applied hydrostatic pressure is presented. The present nonlinear finite element solution methodology includes all the nonlinear terms in the kinematic equations and utilizes the total Lagrangian formulation in the constitutive equations and incremental equilibrium equations. A curved six-node element, based on an assumed quadratic displacement field (in the circumferential coordinate), employs a two-dimensional hypothesis, known as linear displacement distribution through thickness theory, to capture the effect of the transverse shear/normal (especially, shear) deformation behavior. The driving factor behind this analysis is to determine the onset of localization arising out of the bilinear material behavior of the ring with modal imperfection. Numerical results suggest that material bilinearity is primarily responsible for the appearance of a limit or localization (peak pressure) point on the postbuckling equilibrium path of an imperfect ring.     

采用静压式水平电镀槽的带钢电镀锌生产线

描述了采用静压式水平电镀槽的带钢电镀锌生产线。此生产线的特点是应用了自主研发的电镀锌成套技术。其主要项目是：①静压式水平电镀槽（ HHC槽）；②中部双向水平喷射式电解清洗槽；③中部双向水平喷射式酸洗槽；④镀层横向均匀度控制技术等7项电镀配套技术；⑤新型钛阳极板；⑥闪镀镍技术；⑦镀液集中加热和集中冷却技术等。在中国，采用HHC电镀槽的带钢电镀锌生产线（ HHC线）已建设了两条。应用结果表明，这种生产线具有电镀槽性能优越、工作稳定可靠、产品质量好、对原料的适应能力强、电耗低和建设投资小等优点。     

Postbuckling of Moderately Thick Imperfect Rings under External Pressure

A fully nonlinear finite-element analysis for postbuckling response of a moderately thick imperfect ring under applied hydrostatic pressure is presented. The fully nonlinear theory employed here, in contrast to the von Karman approximation generally prevalent in the existing literature, for a moderately thick ring does not, on employment of the conventional Love–Kirchhoff hypothesis (originally developed for the small deflection regime), automatically guarantee vanishing of the transverse normal and shear strains in the large deflection regime. A curved six-node element, based on an assumed quadratic displacement field (in the circumferential coordinate), employs a two-dimensional hypothesis, known as linear displacement distribution through thickness theory, to capture the effect of the transverse shear/normal (especially, shear) deformation behavior. Numerical results show that even for a sufficiently thin ring, the conventional nonlinear theory, based on von Karman approximation, produces an error on the order of 10%.     

Dispersive and Nonhydrostatic Pressure Effects at the Front of Surge

Undular bores and shocks generated by dam-break flows or tsunamis are examined considering nonhydrostatic pressure and dispersive effects in one- and two-horizontal-dimensional space. The fully nonlinear Boussinesq-type equations based on a weakly nonhydrostatic pressure assumption are chosen as the governing equations. The equation set is solved by a fourth-order accurate finite-volume method with an approximate Riemann solver. Several typical benchmark problems such as dam-break flows and tsunami wave fission are tested in one- and two-horizontal-dimensional space. The computed results by the Boussinesq-type model are at least as accurate as the results by the hydrostatic shallow water equations. This is particularly evident near the steep front of the wave, where frequency dispersion can play an important role. The magnitude of this nonhydrostatic pressure and dispersive effect near the front is quantified, and the engineering implications of neglecting these physics, as would be done through the use of a hydrostatic model, are discussed.     

Experiments on the Buckling Behavior of Ring-Stiffened Pipelines under Hydrostatic Pressure

Submarine pipelines are deemed as thin-walled structures in which relative external pressure may be created in some cases of fluid transmission. The certain effect of this type of loading is local buckling and its propagation along the considerable length of the line. In this study, an experimental program has been performed, in which the influence of ring stiffeners on the buckling strength of pipelines is investigated. In the tests, only hydrostatic pressure is considered as the major loading case, and the effect of further loads is neglected. The modes of initial buckling, buckling propagation, postbuckling, and development of yield lines and the final collapse of the pipeline have been closely appraised. It is verified that the buckling threshold highly hikes up by attaching some light ring stiffeners. By decreasing the ring spacing, the difference between buckling and failure loads is diminished and torsion-type yield lines at failure mode occur on the pipe skin.     

Effect of Seepage-Induced Nonhydrostatic Pressure Distribution on Bed-Load Transport and Bed Morphodynamics

Bed-load transport is commonly evaluated in the condition of a hydrostatic pressure distribution of the flow field; while this condition is reasonable for quasi-steady, quasi-uniform rectilinear flows, it cannot be satisfied in a large variety of flow conditions, i.e., near an obstacle as in the case of a bridge pier. The dimensionless Shields number, which contains the assumption of a hydrostatic pressure distribution in its denominator, therefore cannot be strictly applied to evaluate bed-load transport in all the configurations where nonhydrostatic pressure distributions are observed. In the present work, a generalization of the Shields number is proposed for the case of nonhydrostatic pressure distribution produced by groundwater flow. Experiments showing the effects of vertical groundwater flow on the bed morphodynamics are presented. The comparison between the experimental observations and numerical results, obtained by means of a morphodynamic model which employs the new formulation of the Shields number, suggests that the proposed generalization of the Shields number is able to account the effect of the nonhydrostatic pressure distribution on the bed-load transport.     

Structural Stability of Concrete Gravity Dams Strengthened by Rockfill Buttressing: Hydrostatic Load

Rockfill buttressing is often considered to strengthen existing gravity dams that have inadequate stability to resist the estimated hydrostatic and seismic loads. Various simplified methods for static stability analyses of composite concrete–rockfill dams, which represent the rockfill as equivalent forces, are discussed. Numerical analyses of composite dams using nonlinear rockfill and interface constitutive models are then considered. Hydrostatic stability analyses of a 35?m composite dam are carried out to compare the results obtained from simplified methods and numerical analyses. Parametric analyses are performed to investigate the effects of various modeling parameters such as the friction angle of the concrete–fill interface, the friction angle of the concrete–foundation interface, and the reservoir elevation during the fill placement. Numerical analyses results show that lowering the reservoir prior to construction of the rockfill does not have a significant effect on the stress response of the strengthened dam in the case analyzed. For design purpose, it is shown that the simplified minimum/maximum earth pressure method is always on the safe side irrespective of the concrete–rockfill friction angle.     

静液压传动在KQTG-165钻机底盘上的应用

介绍了KQTG-165钻机底盘静液压传动系统的布置方式和液压原理,分析该设备的容积调速特性和DA阀控制方式,说明了静液压传动在井下无轨设备领域有着广泛的应用前景。     

Implementation of an Associative Flow Rule Including Hydrostatic Stress Effects into the High Strain Rate Deformation Analysis of Polymer Matrix Composites

A previously developed analytical formulation has been modified in order to more accurately account for the effects of hydrostatic stresses on the nonlinear, strain rate dependent deformation of polymer matrix composites. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical J2 plasticity theory definitions of effective stress and effective inelastic strain, along with the equations used to compute the components of the inelastic strain rate tensor, are appropriately modified. To verify the revised formulation, the shear and tensile deformation of a representative polymer are computed across a wide range of strain rates. Results computed using the developed constitutive equations correlate well with experimental data. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite for several fiber orientation angles across a variety of strain rates. The computed values compare well to experimentally obtained results.     

金属中气体分析现状与未来

综述了金属中气体分析概况, 提及元素周期表中所有气体元素以及碳和硫。提出常规气体分析已经从氧氮氢碳硫扩大至氦和氩。气体分析所涉及材料种类不断增加, 从金属及合金扩大至冶金炉料、金属氧化物和陶瓷材料等等。气体分析检测极限不断被刷新, 向着更低和更高方向发展。脉冲熔融-质谱新方法应用于金属中气体分析, 可做到氧氮氢氩4元素同时测定, 有可能助推改变气体分析现状。火花源原子发射光谱仪和X射线荧光光谱仪等其他非气体分析专业仪器也正交叉渗入。诸如, 二次离子质谱(SIMS), 离子探针(IM)和电子探针(EP)等微观分析手段一直作为金属中气体分析的辅助手段, 随着未来发展可能转变为主要手段。