高压甲铵冷凝器列管及管板泄漏原因分析及对策

介绍高压甲铵冷凝器列管及管板泄漏情况,对泄漏产生的原因进行分析讨论,对检修方式进行总结,提出今后运行需要采取的防范措施,对设备制造、设备材质、甲铵冷凝器进料方式等提出改进措施和建议。     

Interface regulation effects on mechanical behavior of heterostructure Ti6Al4V/TiAl-based laminated composite sheets

Design of architectured composites with layered-ordered structure can solve the strength-toughness mismatch problem of structural materials. In the present study, heterostructure Ti6Al4V/TiAl laminated composite sheets with different thicknesses of interface layer and TiAl composite layer were successfully produced by hot-pressing technology. The effects of interface regulation and laminated structure on their mechanical properties, crack propagation, and fracture behavior were studied. The results indicated that compressive strength of the sheets increased with the decrease in interface thickness. Compressive strength of TiAl composite sheet with thicker composite layer reached 1481.55 MPa at the arrester orientation with sintering holding time of 40 min, which was 25.96% higher than that of the sheet obtained at 120 min. Analysis indicated that the interface area transferred stress through slip bands and through-interface cracks. Compressive strength at the divider orientation reached 1443.06 MPa, which was 45.78% higher than that of the sheet obtained at 120 min. In this case, the interface area transferred stress through slip bands and along-interface cracks. For TiAl composite sheets with thinner composite layer, compressive strength was further improved to 1631.01 MPa and 1594.66 MPa at the arrester and divider orientations with sintering holding time of 40 min, respectively. The ductile metal layer exerted a significant toughening effect. Both interface regulation and laminated structure transformation could enhance the hetero-deformation induced (HDI) strengthening and improve the comprehensive mechanical properties of the composite sheets.     

6000系铝合金汽车板预时效及组织性能

通过硬度、拉伸和成形性实验及透射电镜、扫描电镜、能谱和金相分析,研究了Mg、Si和Mn含量的变化对6000系汽车板铝合金的显微组织、力学性能及成形性的影响,并探讨适宜的预时效处理工艺.研究结果表明:提高合金中的Mn含量,可增加合金中不可溶结晶相及弥散相粒子的数量,前者对合金的延伸率不利,后者阻碍了合金固溶处理过程中的再结晶.对于Si过剩的合金,提高合金中Mg和Si的质量比和Mn含量会使其强度升高,延伸率、应变硬化指数、塑性应变比和埃利克森值被降低.合金板材固溶处理水淬后立即预时效,较为适宜的预时效(固溶处理后立即在170℃下进行5～10 min的短时预时效)不仅能降低其自然时效的硬度,而且能提高人工时效的硬化效果,有利于车身构件的冲压成形和烤漆硬化能力的提高.     

成形速度及载荷对高强钢板回弹影响的研究

回弹问题一直是高强钢板弯曲成形的难点。本文基于伺服压力机对成形速度、载荷以及滑块行程的可控性,通过控制高强钢板弯曲成形过程中的成形速度、载荷以及滑块的行程位移,在试验的基础上探讨了成形速度及载荷等工艺条件对高强钢板弯曲回弹的影响,并通过ABAQUS有限元软件进行了相关的成形模拟。研究结果表明,随着成形载荷的增大回弹量明显减小,多次折弯可有效减小回弹。另外,成形速度和凸模保压时间对回弹影响不大。因此,在伺服压力机工作环境下,可以通过精确控制成形载荷以及折弯次数来控制高强钢板弯曲回弹量。     

AZ31B镁合金板径向推力充液拉深试验

镁合金板冷成形性能差,采用液压成形的方法可提高其冷成形性能。对AZ31B镁合金板进行径向推力充液拉深试验,分析液压力大小、模具尺寸和坯料尺寸对最大拉深高度的影响规律,并对液压拉深件破裂位置、裂纹走向及裂纹形态进行分析。研究结果表明,当凸模圆角半径较大时,随着液压力的增大,得到的最大拉深高度也大;凸模圆角半径较小时,仅有当液压力大小合适时,才能改善其成形性能;板坯直径越大,最大拉深高度就越小。破裂位置一般在拉深试件的底部圆角、凸缘和侧壁处,且裂纹走向、裂纹断面呈现不同的形态。     

Microstructures and magnetic properties of heatproof domain-refined grain-oriented silicon steel sheets

Microstructures and magnetic properties of heatproof domain- refined grain- oriented silicon steel sheets were studied. Local strains were introduced using two types of gear roll as well as cog tips, one 35 Μm and the other 85 Μm. After the local strains were introduced onto sheets, the distribution of hardness near the groove was measured. The nuclei of micrograins were investigated at various applied rolling loads. After stress-relief annealing, various shapes of microgranes and grooves were observed. The effect of these various shapes of grooves and micrograins on magnetic properties was clarified. The role of micrograins and grooves on domain refining is discussed.     

有机涂层钢板鲜映性影响因素的研究

为提高有机涂层钢板的表观装饰性和工艺优化,对涂层表面鲜映性进行了测量评价,并探讨了影响涂层鲜映性的主要因素及其作用规律。研究表明：降低钢板表面粗糙度、减小涂料的粒度和黏度、增加面漆或底漆的厚度和准确控制面漆烘干温度,均可有效提高钢板鲜映性,改善涂层平滑性。     

BEHAVIOR OF FLOW STRESS OF ALUMINUM SHEETS USED FOR PRESSURE CAN DURING COMPRESSION AT ELEVATED TEMPERATURE

The behavior of flow stress of Al sheets used for pressure can prepared by different melt-treatment during plastic deformation at elevated temperature was studied by isothermal compression test using Gleeble1500 dynamic hot-simulation testing machine. The results show that the AI sheets possess the remarkable characteristic of steady state flow stress when they are deformed in the temperature range of 350-500℃ at strain rates within the range of 0.01-10.0s^-1. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate, and an Arrhenius relationship with the temperature, which implies that the process of plastic deformation at elevated temperature for this material is thermally activated. Compared with the AI pieces prepared by no or conventional melt-treatment, hot deformation activation energy of AI sheets prepared by high-efficient melt-treatment is the smallest （ Q= 168.0kJ/mol）, which reveals that the hot working formability of this material is very better, and has directly to do with the effective improvement of its metallurgical quality.     

无铬及含铬电镀锌耐指纹钢板的性能对比研究

为满足环保需求,宝钢冷轧厂在国内率先成功实现了电镀锌无铬耐指纹薄板的产品稳定化生产.首先简要介绍了宝钢电镀锌耐指纹有机膜钢板的生产状况、主要用途.为了解产品性能,采用多种实验方法重点研究了宝钢新型无铬耐指纹钢板的特性,并与原有含铬产品进行了对比.结果表明,宝钢无铬耐指纹有机膜产品各项性能与原含铬产品性能基本相当,满足用户的使用需求.     

不锈钢超薄板力学性能的尺度效应

为研究304不锈钢超薄板力学性能与试样尺寸、晶粒尺寸的相关性,应用自制的超薄板专用夹具进行拉伸试验,分析超薄板的厚度、晶粒尺寸对材料力学性能的影响。试验结果表明,随着试样厚度减小,材料的屈服强度先减小而后明显增大。这是因为,当试样厚度大于200μm时,表面层效应起主导作用;当试样厚度小于200μm时,应变梯度效应和表面层钝化膜共同作用。同一厚度下,改变试样的晶粒尺寸结果表明,当厚度尺寸和晶粒尺寸的比值小于2时,板料在厚度方向已没有内部晶粒,位错很容易滑移出自由表面,应力-应变曲线显著降低。