Mechanical properties,corrosion resistance,and rubber pad forming of cold differential speed-rolled pure titanium for bipolar plates of proton-exchange membrane fuel cells

Due to problems such as pores on surface-treated coatings, the corrosion resistance of pure titanium bipolar plates for proton-exchange membrane fuel cells can be further improved by increasing the corrosion resistance of pure titanium by using differential speed-rolling (DSR); however, these materials have not yet reached the standard requirements of bipolar plates (corrosion current density i_corr＜10³ nA·cm^?2). In this work, the corrosion resistance of pure titanium was improved by optimizing the DSR process while the strength was maintained. The best corrosion resistance of the DSR pure titanium was achieved when the roller speed ratio was 2, while i_corr was 429 nA·cm^?2 in a solution of 0.5 M H₂SO₄ and 2 mg/L HF at room temperature. The formability of the DSR pure titanium for bipolar plates was verified. The optimal holding pressure range was 6.8–7.0 kN.     

[Zr0.73(Cu0.59Ni0.41)0.27]87Al13合金过冷液相区热塑性成形研究

为探究[Zr_(0.73)(Cu_(0.59)Ni_(0.41))_(0.27)]_(87)Al_(13)非晶合金的热塑性成形性能以及绘制其对应的热加工图谱,用Gleeble3500型热模拟压缩实验机对该非晶合金进行不同参数下的热模拟压缩实验。结果表明,合金在压缩过程中变形行为由牛顿流变演变为非牛顿流变;同时,过高或过低的热加工温度均能导致合金晶化;进一步对数据分析得到该合金在不同热塑性成形参数下的功率耗散图与流变失稳图,并绘制出相应的热加工谱图,谱图分析结果表明,该合金在温度为420与430℃、应变速率为10~(-3) s~(-1)时具有较高功率耗散系数且没有失稳区域,因此,合金可选的热塑性加工参数为温度420～430℃,应变速率10~(-3) s~(-1)。     

Bulging in incremental sheet forming of cold bonded multi-layered Cu clad sheet: Influence of forming conditions and bending

Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives: (1) knowing the bulging behavior of a Cu clad tri-layered steel sheet as a function of forming conditions, and (2) analyzing the bending effect on bulging in an attempt to identify the associated mechanism. A series of ISF tests and bending analysis are performed to realize these objectives. From the cause-effect analysis, it is found that bulge formation in the layered sheet is sensitive to forming conditions in a way that bulging can be minimized utilizing annealed material and performing ISF with larger tool diameter and step size. The bending under tension analysis reveals that the formation of bulge is an outgrowth of bending moment that the forming tool applies on the sheet during ISF. Furthermore, the magnitude of bending moment depending upon the forming conditions varies from 0.046 to 10.24 N·m/m and causes a corresponding change in the mean bulge height from 0.07 to 0.91 mm. The bending moment governs bulging in layered sheet through a linear law. These findings lead to a conclusion that the bulge defect can be overcome by controlling the bending moment and the formula proposed can be helpful in this regards.     

喷射轧制Fe-4.5%Si硅钢片的组织和性能

采用喷射成形和轧制工艺制备了厚度为0.5mm的Fe-4.5%Si高硅钢片，并对其密度、显微组织和电磁性能进行了测试分析，研究结果表明：在最佳的喷射成形和轧制工艺条件下，所制备硅钢片的磁感应强度B25为1.544T、B50为1.641T；铁损P1050为1.437W/kg、P1550为3.43W/kg，说明喷射成形轧制技术可以制备出高磁感应强度、低铁损的高硅钢片。     

IF板与08Al板的成形性能研究

通过模拟成形性试验，对新型超深冲用IF钢板和传统冲压用08Al钢板的冲压成形性能进行了研究．结果表明：IF板的拉深性能、扩孔性能、胀形性能以及“拉深-胀形”复合性能等均优于08Al板，其中，扩孔性能和平面各向异性的改善最为显著；各项试验中，IF板的成形力普遍小于08Al板。     

变形温度和变形程度对Ti－31合金性能和组织的影响

通过高温和室温拉伸试验，研究了变形温度和变形程度对Ｔｉ－３１合金板材性能和组织的影响。结果表明，合金在７５０～８５０℃的温度下变形５％～２０％空冷后，其室温机械性能均能达到材料的技术指标要求。并发现了材料在９００℃的临界变形区。     

冷成型模具低温锌系磷化

研制出适用于冷成型模具高硬度表面的低温锌系磷化工艺。其中磷化液含Zn(H2 PO4 ) 2 ·2H2 O 6 0g/L ,Zn(NO3) 2 ·6H2 O 90g/L ,NaNO2 1.5g/L ,稀土促进剂 0～ 1.0g/L ,游离酸度 4～ 6点 ,总酸度 70～ 75点。该磷化液在 4 0℃下 ,处理 30～ 4 0min后可获得厚约 10 μm的磷化膜。性能测试表明 ,其减摩、润滑性能良好 ,摩擦系数约降 0 .1,与未处理试样相比磨损量下降 96 % ,附着力 1级。     

Recrystallization/precipitation behaviour in microalloyed steels

Microalloyed high-strength low-alloy (HSLA) steels contain additions of Nb, V, Ti, or in combination, in amounts of 0.01 to 0.1 weight percent to improve mechanical properties, which are strongly dependent on the thermomechanical interaction taking place in the course of rolling mill processes. The recrystallizatian of hat-twisted austenite has been investigated in a cylindrical specimen (f 6×50 mm) machined from hat rolled plates of 0,052 wt % Niobium microalloyed steel. Continuous and interrupted torsion test were carried out in the temperature range 1123 K to 1173 K after a solution treatment of 1.5 minutes at 1423 K and torque-twist data were analysed. The various methods were discussed for obtaining results from torsion tests. The effect of precipitation kinetics was appreciated by way of connection t_p/t_p(red), where t_p is the experimental measured time for the peak stress and t_p(red) is the newly defined reduced time. The softening ratio X and time t_0.05R for start of static recrystallization were established.

The correlation between precipitation and recrystallization is presented as a graphs for chosen requirements (temperature of austenitization, carbon and niobium content and strain rate). If temperature goes below 850°C, the restoration processes are hardly suppressed, both are limited by diffusion and Nb(CN) precipitation, which are extended dynamically in the range of strains rates 10⁻² to 1 s⁻¹.

In the present paper, an attempt is made to derive the PRTT diagram and to define all mathematical equations for describing recrystallization times t_0.05R, t_0.5R, t_0.95R and t_0.05P for the start of precipitation. In real metal forming processes such as the hot rolling of plates or strips the knowledge of these parameters and results is extremely important for the the correct microstructure and sheet quality to be obtained.     

内外齿复合冷挤压成型实验研究

通过对轿车转向盘毂件内外齿进行的复合挤压实验研究 ,得到了新式复动式复合挤压模具结构 ,并确定了一种合理的成型工艺方案     

枣35断块沙三段玄武岩储层特征及成藏条件分析

从地质、地震、测井及试油试采等方面入手，并采用新技术，对自来屯构造枣35断块沙三段玄武岩储层特征及成藏条件进行了分析。其结果为该区下一步勘探、开发及进一步研究奠定了基础。