An ultrafine lamellar-structured martensite steel fabricated by heavy warm rolling (HWR) has shown an excellent combination of strength and ductility. By appending tempering at 400 °C to HWR, we show that the comprehensive mechanical property of a lamellar-structured low-carbon martensite steel can be further improved to reach a yield strength of ~ 1.8 GPa, an ultimate tensile strength of ~ 2.0 GPa and a total elongation of ~ 9.3%. This is achieved by tempering the HWR steel from 300 to 750 °C, and the optimum tempering temperature is thus obtained. We find that the tempered ultrafine lamellar martensite contains high-density nanoprecipitates dispersed within the aligned martensite laths with reduced crystallographic variations. The ultrahigh strength of the steel is rationalized as mainly the result of grain boundary strengthening and precipitation strengthening, which contribute to yield stress by 610 MPa and 440 MPa, respectively. The good ductility is believed to be closely related to the capacity of the tempered grains to accommodate dense dislocations upon plastic deformation. The present thermomechanical processing provides a feasible routine for producing steels with ultrahigh-strength and good-ductility.

为了深入认知凹腔驻涡与高速可压缩来流之间的相互作用过程以及来流马赫数对上述动力学过程的内在影响规律,对长深比为1.0的单凹腔基础构型在常温、常压、Ma=0.3～0.7的高速可压缩来流下进行冷态非定常数值模拟,并基于拉格朗日视角研究来流与凹腔驻涡相互作用及其物质输运特性.结果表明:凹腔上方剪切层内旋涡结构仍然具有类似自由剪切层的周期性演化过程,主流与凹腔通过三次掺混进行物质输运;随着主流马赫数的增加,旋涡运动方式及凹腔-主流物质掺混机制都发生了本质上的改变,剪切层内旋涡和凹腔主涡涡量均呈现数量级式增长,剪切层旋涡结构脱落频率近似线性增长并逐渐卷吸至凹腔中部,进入凹腔的主流流体占比降低,但扩散程度和速度加快;此外,源于凹腔的流体流出唇口线后经剪切层的夹带作用回流占比增大,降低了凹腔-主流的整体质量交换水平;驻留参数整体衰减,高马赫数时仅为低速工况的1/2,显著降低了回流区对于流体驻留作用的贡献.

Mo is widely used as an effective microalloying element to improve mechanical performance of inter phase precipitation steels, but the precise role of Mo in interphase precipitation behavior is not fully understood. In this contribution, interphase precipitation behavior in a series of Ti-Mo-bearing low carbon steels is systematically studied, and the role of Mo in interphase precipitates and its coarsening behavior is revisited. It is found that (Ti, Mo)C precipitates instead of TiC are formed in the Mo-containing alloys, and the average site fraction of Mo in (Ti, Mo)C is almost independent of the bulk Mo content. Moreover, the number density of interphase precipitates can be substantially enhanced by a minor addition of Mo, albeit it does not further rise with increasing the bulk Mo content. This is because the Mo fraction in (Ti, Mo)C rather than the bulk Mo content governs the driving force for precipitation nucleation and the interfacial energy of the (Ti, Mo)C/alpha and (Ti, Mo)C/gamma interfaces. In addition to the reduced interfacial energy, decrease of Ti trans-interface diffusivity has been identified as another key reason for the enhanced carbide coarsening resistance in Mo-containing alloys. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

以植物油基多元醇蓖麻油(CO)、多元醇2010A、三羟甲基丙烷(TMP)和1,4-丁二醇(BDO)为A胶羟基基团基本原料,PM200为B胶异氰酸酯基团基本原料,制备得到透水路面用无溶剂双组分聚氨酯胶粘剂,并对胶粘剂的力学性能和耐紫外老化性能进行了测试.研究结果证明:保持A胶中扩链剂的羟基物质的量总量不变,当TMP与BDO的羟基物质的量之比为1:1时,聚氨酯胶粘剂的拉伸强度和断裂伸长率可达15.53 MPa和56.59％;在保证韧性基础上另添加0.15％气相Si02时,胶粘剂的拉伸强度提高至19.53 MPa.耐紫外老化性能表明,采用多元醇2010A制得的胶粘剂相比初始拉伸强度提高14％,断裂伸长率下降30％;相对于聚酯多元醇两个配方(XCPA和耐水解2010A),其力学性能较为稳定.

概述了传统的溶剂型涂料与环保型水性涂料在使用要求、基本性能、功能等方面的差异,重点对近年来水性无机富锌涂料、水性环氧涂料、水性丙烯酸涂料、水性聚氨酯涂料的主要成份、特点及最新研究进展进行分析,并介绍了 4类涂料的优、缺点及其应用前景;阐述了环保型水性涂料在汽车、铁路车辆、集装箱及重防腐中的应用现状及进展;对当前环保型水性涂料的研究做出了展望.

研究了正硅酸乙酯(TEOS)在片状铝颜料表面水解缩聚形成SiO2包覆膜制备Al颜料的反应过程,重点探讨了两阶段升温变化对包覆性能的影响.FE-SEM和刮板试验结果表明:第一阶段温度50℃,第二阶段80℃时,能在片状铝颜料表面形成一层均匀、致密且遮盖性高、光泽高的SiO2薄膜;EDS和粒径分布测试结果表明:与未包覆的铝颜料相比,SiO2包覆的Al颜料表面硅元素含量增加了1.48％,氧元素含量由1.81％增加到4.60％,SiO2包覆的Al颜料的D50增大了约15％,表明在铝颜料表面形成的SiO2包覆膜非常薄;在pH为9的弱碱性溶液中,220 h后析出的H2体积仅为未包覆铝颜料的2.2％,具有良好的耐弱碱性.

The nano-grained (NG) high-Mn austenitic steel with average grain size of 60 nm and the ultrafine-grained (UFG) steels with grain size below 500 nm are successfully produced by combination of the asymmetric rolling (ASR) and symmetric rolling (SR) method and the subsequent annealing treatment. The annealed NG steels exhibit relatively higher strain hardening and good balance of strength and ductility, which is attributed to the partial recrystallization of the nanostructures and the relatively lower stacking fault energy of the high-Mn TWIP steel.

A metallurgical model concerning the co-effect of the Nb solute drag and the complex carbonitride precipitates pinning is proposed to predict the recrystallization austenite grain growth of low carbon Nb-containing microalloyed steels.The analysis,both predicted and experimental,reveals the precipitate pinning plays a dominate role in suppressing the austenite grain growth with less Nb solute drag effect in high temperature region whereas the Nb solute drag predominates in relatively low temperature region.A factor p is suggested to assess the effectiveness of drag and pinning.The pinning and the drag are more effective in restraining grain growth as p0 and p0,respectively.A low carbon Nb microalloyed steel and a kind of Ti-modified low carbon Nb steel by Ti substituting for part of Nb are employed to validate the modeling results.The theoretical calculations show a good agreement with experimental results.

A metallurgical model has been developed to predict the austenite grain growth in Nb microalloyed steels. The mutual effects of Nb(CN) particle pinning and Nb solute drag on grain growth kinetics are studied. The particle dissolution, the undissolved particle coarsening and the changes in Nb solute in solution during reheating or isothermal heat treatment process are taken into account in the model. It is shown that, besides the pinning exerted by the NbC precipitates, the solute drag of Nb in solid solution plays an important role in the inhibition of austenite grain growth in Nb microalloyed steels. The Nb solute drag effect on grain growth decreases with increasing temperature because the grain boundary can gradually break away from the solute atmosphere in the higher velocity region at high temperature. The mean austenite grain size sluggishly increases with temperature in the low temperature region, while it significantly increases in the relative high temperature region. The predicted austenite grain size concerning the combined effect of Nb drag and Nb(CN) pinning is in good agreement with the experimental results from the literature.

A kinetic equation for austenite grain growth has been derived concerning the mutual effect of NbC and Nb solute in low carbon Nb-microalloyed steels. It is shown that both solute drag of Nb in solid solution and pinning of NbC particles inhibit the grain boundary migration during grain growth after recrystallization in low carbon Nb-microalloyed steels. At high temperatures the NbC pinning plays a dominate role for retarding the austenite grain growth with less Nb solute drag effect. An obvious Nb solute drag restraint was, however, observed at relatively low temperatures. Also, the theoretical calculations are in good agreement with experimental results. The effectiveness of drag effect of soluble atoms and pinning effect of precipitates can be characterized by a p factor. The pinning of precipitates and solute drag of soluble atoms are more effective for suppressing grain growth as p > 0 and p < 0, respectively. And the ratio of Nb in solute and Nb in precipitate as p = 0 reaches the priority and most effectively retards the grain growth. In the traditional hot rolling or austenitizing temperature range, a strong suppression for grain growth after recrystallization could be obtained due to those fine NbC particles smaller than 10 nm in Nb-microalloyed steels.

On the basis of the classical nucleation theory, a new model of incubation time for austenite to ferrite transformation has been developed, in which the effect of deformation on austenite has been taken into consideration. To prove the precision of modeling, ferrite transformation starting temperature (A(r3)) has been calculated using the Scheil's additivity rule, and the A(r3) values were measured using a Gleeble 1500 thermomechanical simulator. The A(r3) values provided by the modeling method coincide with the measured ones, indicating that the model is precise in predicting the incubation time for austenite to ferrite transformation in hot deformed steels.

Two cyano-substituted N,N'-diphenylstyrylanilines were synthesized,which incorporated both hole-transport group(triphenylamine substituent) and electron withdrawing group(cyano substituent).Study showed that cyano substituent lowerd the HOMO and LUMO energies and increased the electron affinity of molecules,thus improved the efficiency of electron injection and potential efficiency of molecules.EL device fabricated with these molecules showed good stability and low onset voltage.