热处理工艺对低温压力容器用钢组织性能的影响

对低温压力容器用09MnNiDR钢板热轧、正火和回火后组织进行观察,分析热处理工艺对该钢组织的影响规律.结果表明,正火后钢板晶粒明显细化,沿厚度方向均得到铁素体+片层珠光体组织,珠光体分布更均匀;回火后大部分片层状珠光体组织消失,渗碳体由片层状变为球形,且组织中大量弥散的纳米级微合金粒子的析出导致部分铁素体晶粒内部位错密度仍较高.最终回火态钢板力学性能的检测结果表明,实验所得回火态钢板综合性能良好.     

09CuPCrNi耐候钢干湿交替加速腐蚀的锈层结构与形成机理

对09CuPCrNi耐候钢干湿交替加速腐蚀后的锈层进行观察与分析,探讨了锈层的形成机理。结果表明,09CuPCrNi钢干湿交替加速腐蚀的锈层包括紧贴基体的致密内锈层和疏松的外锈层两部分。随着腐蚀周期的增加,内锈层增厚,而且更为致密。通过对比锈层中各物相的含量分析,发现y-Fez03在内锈层中的含量高于外锈层,这是内锈层比外锈层更加致密的原因。同时,内锈层中Cu、P、Cr等元素明显富集,可使其更容易形成相对稳定的y-Fe2O3相。     

7A09铝合金管材阳极化后表面出现"黑条"的原因

7A09铝合金管材经切削加工和阳极氧化后少数工件表面有“黑条”,影响用户使用。对“黑条”处进行宏观组织和显微组织观察及分析研究认为:“黑条”是由于管材的毛坯管锭表面的偏析瘤未车削净,而挤入管材内形成化合物富集区,化合物富集区在阳极氧化时优先反应而形成的。     

不同焊接方法对09CuPCrNi薄板搭接接头组织和性能的影响

采用电阻点焊、胶接点焊和塞焊三种焊接方法,对3mm+3mm 09CuPCrNi钢搭接接头的组织和力学性能进行对比研究。结果表明:三种焊接方法下焊接接头的剪切拉伸性能均满足标准,其中塞焊时接头剪切拉伸性能较好;电阻点焊和胶接点焊接头各区域硬度相近且高于塞焊下接头各区域硬度;塞焊接头的组织与电阻点焊和胶接点焊接头组织有所不同;点焊及胶接点焊焊接接头的熔透率均满足相关标准。     

09MnNiD钢马氏体大压下量温轧及低温退火后的组织与力学性能

利用Gleeble-3500热模拟试验机测定了不同温度下试验钢温变形的流变应力,对淬火09MnNiD钢板条马氏体组织进行了多道次压下量大于70％的温轧及低温退火试验。用透射电镜（TEM）观察分析了经过不同温变形以及不同温度退火后的微观组织,利用TEM暗场弦线法和X射线衍射谢乐法测定并计算了晶粒尺寸,在热模拟试验机上对退火样品进行拉伸试验。结果表明,温轧后在300～600℃进行退火可获得细小的纳米晶粒和超细晶粒钢板;拉伸试验表明,温轧钢板在〈450％下退火后的抗拉强度变化不大,当退火温度在550％及以上时抗拉强度显著下降。     

An early warning criterion for the prediction of snowmelt-induced soil slope failures in seasonally cold regions

In Hokkaido, Japan, soil slope failures occur frequently during the snow melting season. These slope failures are triggered by the excess amount of water derived from snowmelt and rainfall. For the prediction of snowmelt-induced soil slope failures in seasonally cold regions, an early warning criterion is required. The existing Japanese early warning criteria for sediment disasters, i.e., the relationship between the 60-min cumulative rainfall and the Soil Water Index (SWI), the effective rainfall index etc., consider the influence of rainfall and the time-dependent random moisture of the soil. However, these criteria do not consider the soil moisture contributed by the snowmelt water. In this study, therefore, the applicability of the existing early warning criteria to predict snowmelt-induced soil slope failures is examined. An empirical method to quantify the amount of snowmelt water is presented. Various scenarios of conceptual soil slope failures are studied using numerical simulations under different magnitudes of rainfall and snowmelt water. As a result, a revision is introduced for the SWI and the effective rainfall index, adding the amount of snowmelt water to that of rainfall, and slope failure scenarios are studied. Based on the results, a new early warning criterion, the Effective Precipitation (EP) index, is introduced. It is found that the new failure criterion performs well for the prediction of snowmelt-induced soil slope failures.     

Stability of pile foundations base on warming effects on the permafrost under earthquake motions

The Qinghai–Tibet Railway (QTR) is approximately 1142 km long, of which 275 km are underlain in warm permafrost regions (mean annual round temperatures range from 0 °С to 1.5 °С), where the stability of the embankment would be greatly affected by minor temperature variations. Furthermore, since the Qinghai–Tibet Plateau (QTP) is in an active seismic zone, special attention needs to be paid to the relationship between earthquakes and soil temperature. Using a refrigeration system, a series of shaking table tests for the 1/100 scaled model of the pile foundation in the Qingshui-river Bridge along the Qinghai–Tibet Railroad were conducted for soil temperatures of below 0 °С around the pile. The results indicated that the seismic mechanical properties are extremely sensitive to soil temperature. The change of temperature around the pile foundation during the earthquake motions was monitored, and the warming effects on the permafrost were assessed. In addition, the seismic stability coupled with the effect of soil temperature of the pile foundation in the Qingshui-river Bridge was evaluated.     

Characterization of potassium glycinate for carbon dioxide absorption purposes

Aqueous solutions of potassium glycinate were characterized for carbon dioxide absorption purposes. Density and viscosity of these solutions, with concentrations ranging from 0.1 to 3 M, were determined at temperatures from 293 to 313 K. Diffusivity of CO₂ in solution was estimated applying the modified Stokes-Einstein relation. Solubilities of N₂O at the same temperatures and concentrations were measured and the ion specific parameter based on Schumpe's model was determined for the glycinate anion; the solubilities of CO₂ in these solutions were then computed.The reaction kinetics of CO₂ in the aqueous solution of potassium glycinate was determined at 293, 298 and 303 K using a stirred cell reactor. The results were interpreted using the DeCoursey equation for the calculation of the enhancement factor. The rate of absorption as a function of the temperature and solution concentration for the conditions studied was found to be given by the following expression: