提高马氏体时效不锈钢超低温韧性的热稳定化新工艺

研究了新的热稳定化处理工艺对马氏体时效不锈钢微观组织和超低温度韧性的影响,即在冷处理之前增加一道低于时效温度的热稳定化处理,除观察微观组织变化外,着重用X射线衍射方法检测不同温度热稳定化处理对最终的残留奥氏体量的影响,并对比观察了对力学性能的影响.研究结果表明,固溶处理后增加200～450℃热稳定化处理,明显抑制了随后...     

Ti-B20合金组织性能与时效温度的关系

采用OM、X射线衍射仪、SEM等研究了固溶时效对高强亚稳态Ti-B20合金组织性能的影响。结果显示:合金经固溶时效后,由α相和β相组成;随时效温度的升高,析出相由针状变成片层,尺寸增大且由晶界处优先析出,合金抗拉强度随温度的升高而下降。     

硼铸铁在机床导轨上应用的试验研究

本文着重研究缓慢冷却条件下硼铸铁硬化相特征及硼对石墨和基体组织的影响;通过系统试验,论证硼铸铁耐磨性、机械性能、铸造性能;探讨硼铸铁的尺寸稳定性和时效工艺;介绍硼砂熔液加硼法。证明硼铸铁获得适当组织的生成条件宽,可以扩大使用,机床导轨采用硼铸铁,具有优异的耐磨性,其尺寸稳定性也明显提高。     

稀土钇对不同处理状态镁-铝-钙-钛铸造镁合金组织和硬度的影响

用X射线衍射仪、光学显微镜检测和观察了铸态、固溶态和时效态镁-铝-钙-钛铸造镁合金的相结构和显微组织,并测试了不同状态镁合金的硬度,探寻稀土元素钇及不同热处理对铸造镁合金的相结构、显微组织和硬度的影响.结果表明:随钇元素加入增多,镁合金第二相的析出增加,分布更均匀,且晶粒尺寸减小;铸态显微硬度显著提高;时效和固溶处理对其显微组织有明显的影响,但对硬度影响不大.     

固溶处理工艺对HR3C奥氏体耐热钢组织和性能的影响

研究了固溶温度、保温时间对固溶态及固溶+时效态HR3C奥氏体耐热钢显微组织及力学性能的影响。结果表明:试验钢在1 150~1 200℃固溶处理30 min后的晶粒尺寸变化不大,超过1 200℃后晶粒明显长大;保温时间对晶粒尺寸无明显影响;随固溶温度的升高和保温时间的延长,时效后钢中一次析出相的尺寸变小、数量减少;在700℃的时效过程中,M23C6相沿晶界析出,二次析出的Z相弥散分布在晶内,尺寸在100 nm以下,时效时间超过1 000 h后M23C6相明显粗化,Z相的尺寸变化不大,但数量不断增多,在长时时效过程中起到显著的析出强化作用;随初始固溶温度的升高和保温时间的增长,相对应的长时时效态的高温屈服强度明显提高。     

热处理对21-6-9钢性能及显微组织影响

热处理工艺对单相高强度21-6-9奥氏体不锈钢显微组织及力学性能影响显著。本文在固定其他热处理工艺参数情况下,分别对固溶处理温度,固溶冷却方式,时效处理温度进行研究,结果表明:固溶温度对21-6-9钢低温韧性及晶粒尺寸影响显著,1050℃是其最佳固溶处理温度;固溶冷却方式对其力学性能影响不明显,但对其晶粒尺寸有较大影响,其中水冷处理方式能够使21-6-9钢得到尺寸均匀且细小的晶粒组织;时效温度对其低温韧性存在影响,表现为时效温度过高(≥600℃)会导致低温韧性明显下降。经过适当的热处理工艺处理,实现21-6-9钢屈服强度不低于438MPa,断口伸长率47%,断口收缩率不低于75%,同时具有良好的塑性及低温韧性。     

固溶和稳定化处理后Zr-Mo微合金化310S不锈钢的显微组织和耐腐蚀性能

制备了Zr-Mo微合金化310S不锈钢并进行了不同温度(1 050~1 150℃)固溶处理以及1 150℃固溶+不同温度(950~1 1050℃)稳定化处理,研究了不同热处理后试验钢的显微组织和耐腐蚀性能。结果表明:固溶处理后,试验钢的显微组织为均匀的奥氏体等轴晶,且晶粒内有大量退火孪晶,晶界或晶内析出条状或球形颗粒状(Zr,Mo)C相和块状Zr(C,N)相;1 150℃固溶+不同温度稳定化处理后试验钢的显微组织与固溶态的相似,但析出相数量增多,且在950℃稳定化处理后,晶界上析出了大量的链球状M23C6相;950~1 050℃的稳定化处理对试验钢的耐均匀腐蚀性能影响不大;随着稳定化温度的升高,试验钢的晶间腐蚀敏感性降低,耐晶间腐蚀能力增强。     

频谱谐波时效在风电球磨铸铁件中的应用研究

介绍了频谱谐波时效技术在去应力处理效果和保持尺寸精度稳定性方面的作用,对风电球墨铸铁材料工件(样件)处理后,经对残余应力和工艺变形量测定表明,此技术可以替代以消除应力为目的热时效工艺,达到防止工件变形、开裂、提高工件尺寸精度和尺寸稳定性的目的。     

热拉伸变形及固溶时效处理对TC4-DT钛合金显微组织的影响

分别在α+β两相区(925℃)、近β两相区(960℃)、准β单相区(995℃)对TC4-DT钛合金进行等温恒应变速率热拉伸变形,再进行920,940,960,980℃固溶和550,720℃时效热处理,研究了其流变应力的变化趋势和不同工艺处理后的显微组织。结果表明:在拉伸变形初期,流变应力迅速增大至峰值后缓慢减小,同时流变应力降幅随变形温度的升高而减小;拉伸变形温度越高或变形量越大,组织中初生α相量越少,针状α相越多,形成的片层组织越多;经960,995℃拉伸变形和不同温度固溶处理后,固溶温度越高,析出的针状α相越多,越易形成片层组织;经拉伸变形、固溶和时效处理后的显微组织和时效处理前的差别不大,但在针状α相间的β相上析出了次生α相,且时效温度越高,针状α相越粗大,片层组织越明显。     

含微量B的X2 CrNiMo 18.12钢的固溶热处理

利用OA和SEM等分析方法研究固溶热处理工艺对含微量B元素的X2 CrNiMo 18.12不锈钢组织与机械性能的影响。结果表明,经1 050～1 070℃固溶处理后,不锈钢中碳氮化物等析出相回溶较为充分,晶粒尺寸中等且较为均匀,固溶强度最高;当固溶温度达到1 100℃时,不锈钢晶粒尺寸快速长大;微量B能提高不锈钢的高温屈服强度,B元素含量为0.001 7 wt.%的X2 CrNiMo 18.12不锈钢的高温屈服强度随着固溶冷却速率的升高而增大;B能增大不锈钢在1100℃以上固溶时晶粒快速长大的倾向。     

氧化铌在玻璃结构中的特性及其应用

本文将铌硅酸盐玻璃结构与性能的理论研究成果应用于光学玻璃研制过程。在LaF₂、LaF₃和LaF₄等稀土光学玻璃中,引入了Nb₂O₅,极大地改善了工艺稳定性,显着地提高了光学玻璃的内在质量和成品率,本工作为稀土光学玻璃的研制与生产提供了又一新的途径。     

薄膜应力的测定

本文介绍一种利用长焦距显微镜观察玻璃薄片由镀膜淀积引起的形变来测量薄膜应力的方法。对于该实验装置的几个主要结构部份、测量的原理及方法和提高测量精度所采取的主要措施作了较详细的描述。最后给出了在不同真空度和蒸发速率时硫化锌膜、氟化镁膜及硫化锌—氟化镁多层膜的应力分别随薄膜几何厚度而变化的实验结果。     

高韧性高耐磨性冷作模具钢的开发与研究

本文将平衡碳理论加以推广,并根据此理论在Cr₁₂ MoV钢的基础上,调整合金元素含量,加入适量稀土,设计出11种不同成分比的合金钢,通过冶炼、热处理、性能实验等的综合研究,找出了最佳合金元素含量。实验结果表明:符合“平衡碳”理论的新型合金钢,其共晶碳化物细小,与Cr₁₂MoV比较,硬度变化不大,但韧性和耐磨性显著增高。     

Al(PO3)3-NaBF4-AlF3氟磷系统玻璃的研究

本工作利用IR、Raman、X-ray, RTEM及DTA技术首次研究了Al(PO₃)₃-N₃BF₄-AIF₃系统玻璃的基本性质与结构特点, 得出了分相机理及分相与晶化之间关系.实验结果指出, 该系统在高磷区基本保持偏磷酸盐结构.随着A1(PO₃)₃含量降低, 结构逐渐由偏磷酸盐向焦磷酸盐变化.该系统的分相属成核生长机理, 粒子长大服从扩散机制.分相导致整体析晶.     

Continuous measurement of the arrival times of x-ray photon sequence

In order to record x-ray pulse profile for x-ray pulsar-based navigation and timing, this paper presents a continuous, high-precision method for measuring arrival times of photon sequence with a common starting point. In this method, a high stability atomic clock is counted to measure the coarse time of arrival photon. A high resolution time-to-digital converter is used to measure the fine time of arrival photon. The coarse times and the fine times are recorded continuously and then transferred to computer memory by way of memory switch. The pulse profile is obtained by a special data processing method. A special circuit was developed and a low-level x-ray pulse profile measurement experiment system was setup. The arrival times of x-ray photon sequence can be consecutively recorded with a time resolution of 500 ps and the profile of x-ray pulse was constructed. The data also can be used for analysis by many other methods, such as statistical distribution of photon events per time interval, statistical distribution of time interval between two photon events, photon counting histogram, autocorrelation and higher order autocorrelation.     

Mg(PO3)2-AlF3-PbF2系统玻璃振动光谱的研究

由FT—IR和Raman光谱的结果得出:该三元系统玻璃在高磷区为偏磷酸盐结构。其结构网络主要由[O=PO_3/2四面体组成的链状和少许环状分子构成。随着PbF₂含量的增加,链开始断裂。当过渡到中磷区时,又主要以[Al(O,F)₄]和[P(O,F)₄]四面体及焦磷酸盐结构状态存在。当[Al(O,F)₄]和[P(O,F)₄]两者的比值为1∶1时,将无法形成玻璃。实验结果还指出,上述系统在中磷区的形成玻璃的范围是很小的。到低磷区时,由磷氧构成的网络几乎不存在,仅以孤立的[P(O,F)₄]四面体即氟正磷酸盐结构存在,同时双键氧P=O也消失。     

Residual stress evaluation in dissimilar welded joints using finite element simulation and the L CR ultrasonic wave

Subsurface stresses in welded structures increase the likelihood of fatigue cracks and environmental induced material degradation. The ability to evaluate stresses at the surface as well as in the interior of welded structural members would substantially increase the accuracy of structure life estimation. The longitudinal critically refracted (L _CR) wave is a bulk longitudinal mode that travels within an effective depth underneath the surface. It may be used to detect in-plane subsurface stresses in the structures. This paper presents a three dimensional thermo-mechanical analysis to evaluate welding residual stresses in dissimilar plate-plate joint of AISI stainless steel 304 and Carbon Steel A106-B type. After finite element simulation, the residual stresses were evaluated by L _CR ultrasonic waves. Finally the results of two methods were compared and verified by hole-drilling method. This paper introduces a combination of ??Finite Element Welding Simulation?? and ??Ultrasonic Stress Measurement using the L _CR Wave?? which is called as ??FEL _CR??. The capabilities of FEL _CR??. The capabilities of FEL _CR in residual stress measurement are confirmed here. And also this paper evaluates residual stresses of dissimilar welded joints by LCR ultrasonic waves. It has been shown that predicted residual stress from three dimensional FE analyses is in reasonable agreement with measured residual stress from LCR method and also the results of both are verified with hole-drilling experimental measurements.     

注塑制品残余应力数值模拟的研究

通过预测和优化注塑成形中的残余应力，可以提高注塑制品最终形状的尺寸稳定性和力学性能。采用线性粘弹性模型，计算了无定形热塑性材料在成形过程中由温度和压力引起的残余应力。该模型可以较好地反映成形过程中的应力松弛现象和保压压力对残余应力的影响。通过采用在时间上进行差分和在厚度方向进行分层处理的方法，结合注塑成形中的特定边界条件，建立了残余应力的数值计算方法，并采用该方法模拟计算了典型注塑件的残余应力。结果表明：在脱模时刻，制品的表层有着较大的拉应力，袁层以下存在着一个应力低谷，在制品中间区域存在着抛物线形的应力分布。     

High-temperature residual stresses in thin films characterized by x-ray diffraction substrate curvature method

A new x-ray technique to determine temperature dependencies of macroscopic stresses in thin films by characterizing the substrate curvature is introduced. The technique is demonstrated on polycrystalline TiN and Al thin films deposited on Si(100) wafers. The structures are thermally cycled in the temperature range of 25-400 degrees C using a newly developed heating chamber attached to a commercial x-ray diffractometer. The curvature of the freestanding samples was determined by the rocking curve measurement of substrate Si 400 reflections at different lateral positions of the samples, and the stresses are calculated using Stoney's formula. The results show that the magnitude of the stress is in good agreement with the results obtained by other techniques. For the practical application of the technique, the sample mounting and the temperature control are of great importance.     

On the mixing flow structure of a turbulent cross jet

An experimental study on the structure of a turbulent cross jet mixing flow is presented. Diffusion rates, two and three dimensional flow structures, mean velocities turbulence intensities and turbulent shear stresses of the mixing flow were measured as varying the velocity ratio. Self-similar forms for the dimensionless mean velocity and turbulent shear stresses was obtained by correlating the measurement data resulting a remarkable agreement. It was found that the deviation gradient(a) is linearly correlated with the velocity ratio(R), and the cross section of the mixing flow is an elliptic form.