XZ—1型树脂砂性能的研究

对ＸＺ－１型树脂砂的高温强度，残余强度等进行了实验，并测定了几种原砂所混制的树脂砂的强度，对不同硬化条件下硬化的树脂膜进行了热失重和差热分析。     

MSP试验法评价MoSi2系复合材料高温力学性能

采用MSP（Modified Small Punch）试验法对MoSi2系复合材料的高温力学性能进行评价，不仅能方便地得到各组分复合材料高温强度随温度的变化，还能得到各组分复合材料的脆性延性转变温度，其结果和材料的微观结构相对应。对MoSi2系复合材料高温蠕变测试表明，MSP试验法得到的蠕变曲线和传统方法类似，而且随着氧化物添加相含量的增加，复合材料的高温蠕变性能下降。MSP试验法评价陶瓷材料的高温力学性能方便有效。     

镀铝用铸铁坩埚组织与性能的研究

针对热浸镀铝的服役条件,从耐浸蚀性、抗氧化性及高温强度三个方面对铸铁组织及性能进行了研究。认为细小均匀分布的Ａ型石墨对提高耐铝液浸蚀性能有重要作用,铬可以提高高温氧化性能及高温强度。试验结果表明,碳的适宜含量为２９％～３１％,铬的适宜含量为１０％～１２％。     

采用15Cr5MoV新材质提高连铸机拉矫辊的质量和寿命

本文从磨损、弯曲、裂纹三方面分析了连铸机拉矫辊的失效形态和原因。通过试验,从抗高温氧化腐蚀、高温强度和高温断裂韧性等方面对不同材质的拉矫辊进行了对比。试验表明,采用15Cr5MoV 钢能显著提高连铸机拉矫辊的寿命。     

汽车排气管用Nb-Ti铁素体不锈钢在高温时效过程中的力学性能变化

对含Nb-Ti和铌铁素体不锈钢进行高温时效和固溶处理,通过高温拉伸试验研究其高温力学性能变化。结果表明,随着时效时间的延长,铌钢的高温屈服强度下降很快,而Nb-Ti钢的高温屈服强度并没发生较大变化。     

碳在Ni-Cr-W铸造高温合金中作用的研究

采用真空感应炉、金相显微镜、扫描电镜及X射线衍射等手段 ,研究 115 0℃下C对Ni Cr W高温合金的组织和高温强度的影响。结果表明 ,随C含量增加 ,合金中的碳化物数量逐渐增加 ,形状由小块状、岛状逐步变为连续、半连续网状 ;合金的高温蠕变能力随C含量增加逐渐下降 ,下降到一定值C(w )为 0 .3%后 ,又逐渐上升     

Si复合Al2O3-SiC材料热机械性能的研究

通过应力-应变关系、高温抗折强度等高温试验，研究了金属硅复合Al2O3-SiC材料的热机械性能，结合SEM和XRD，对金属硅复合Al2O3-SiC材料高温显微结构和物相进行分析。结果表明：金属硅作为一个组元，不仅能缓解Al2O3-SiC材料由于热膨胀系数不匹配产生的内应力，而且使Al2O3-SiC材料兼具有金属塑性的特点，从而改善了Al2O3-SiC无机材料热机械性能。     

Si复合Al2O3-SiC材料热机械性能的研究

通过应力-应变关系、高温抗折强度等高温试验,研究了金属硅复合Al2O3-SiC材料的热机械性能,结合SEM和XRD,对金属硅复合Al2O3-SiC材料高温显微结构和物相进行分析.结果表明:金属硅作为一个组元,不仅能缓解Al2O3-SiC材料由于热膨胀系数不匹配产生的内应力,而且使Al2O3-SiC材料兼具有金属塑性的特点,从而改善了Al2O3-SiC无机材料热机械性能.     

高温作用后C20混凝土强度的无损检测

C20混凝土试块在450℃高温下持续不同时间后自然冷却，再对其进行超声、回弹综合法及标准抗压强度试验，以探讨同一高温不同时间作用后混凝土强度的变化规律，分析无损检测与标准抗压强度试验之间的关系。     

钢水成分对钢的高温力学性能和CSP薄板坯表面纵裂的影响

从钢水成分影响钢的高温力学性能的角度,研究钢水成分对钢的高温力学性能和CSP薄板坯表面纵裂的影响.研究表明,钢在高温下的临界应力和临界应变是决定裂纹形成的内因,钢的高温塑性对CSP铸坯裂纹的形成起主要作用,添加提高钢的高温强度和塑性的化学元素对减轻表面纵裂的发生有利.     

电弧熔炼态NiAl-39V共晶合金的组织及力学性能

采用真空非自耗电弧熔炼制备了Ni-30.5A1-39V (at%)合金,利用光学显微镜(OM),X射线衍射(XRD),扫描电镜(SEM)分析了合金不同凝固位置处的相组成和组织形态,结果表明:Ni-30.5Al-39V合金的凝固组织由NiAl+V片层共晶组成。通过断裂韧性和高温压缩的测试表明:NiAl-39V合金的断裂韧性是NiAl合金的3倍,裂纹偏转和裂纹键合是其主要韧化机理。高温强度提升约2倍左右,复相强化和固溶强化是高温强度提升的主要原因。最后,基于Arrhenius模型构建NiAl-39V合金本构关系为ε=5.398[sinh(0.037128σ)]~(2.3)exp(-109.95×10~3/RT),其激活能为109.95 kJ·mol~(-1)。     

耐热镁合金的研究进展

综述了耐热镁合金的发展历史,以及近年来耐热镁合金研究发展现状.主要介绍了Mg-RE系、Mg-Al系、Mg-Zn系3 类主要耐热镁合金的耐热机理和研究发展.本文提出了耐热镁合金的未来的发展趋势.     

Effects of alloying on the microstructures and mechanical property of Nb-Mo-Si based in situ composites

Nb-Mo-Si based alloys have been prepared by arc melting in a water-cooled copper crucible under an argon atmosphere. The effects of Al, Cr, Hf and Ti additions on the phase components and stability, microstructures and mechanical property of Nb-Mo-Si based alloys have been studied. The results indicated that the additions of Al, Cr and Ti elements do not change the phase components of Nb-20Si-6Mo alloys, which are composed of Nb solid solution (Nb_ss) and β-Nb₅Si₃. The phase component is α-Nb₅Si₃ and Nb_ss in Nb-20Si-6Mo-3Hf alloy. The additions of Cr and Ti element make the Nb_ss/Nb₅Si₃ eutectic morphology anomalous and coarsening. The element segregation is obvious found with the additions of Hf and Ti. The enrichments of Hf and Ti change the compositions of retained melt and promote the formation of fine eutectic structure. After heating treatment at 1873K for 10 h, β-Nb₅Si₃ phase translates into α-Nb₅Si₃ phase and γ-Nb₅Si₃ phase. The eutectic structures tend to anomalous and coarsening. The Ti solid solution (Ti_ss) phase was found in Nb-20Si-6Mo-20Ti alloy and the formation mechanism of Ti_ss phase was discussed. The high temperature (1523 K) compression strength of as cast Nb-Mo-Si based alloys increased with the additions of Al, Cr, Hf, and decreased with Ti addition.     

Electrically assisted blanking using the electroplasticity of ultra-high strength metal alloys

The electroplastic tensile behavior of ultra-high strength steels (UHSS) subject to a single pulse of electric current is briefly introduced, and electrically-assisted (EA) blanking, which utilizes this electroplastic characteristic, is suggested. The experimental result shows that the blanking load of EA blanking is clearly lower than that of blanking with local resistance heating, which is lower than that of cold blanking. No significant change in material properties was observed in the EA blanked parts at the electric energy densities selected in the present study. EA blanking or trimming is expected to minimize or even eliminate the need for expensive and time-consuming laser trimming in the manufacture of automotive parts using UHSS.     

Evolution of Microstructures of a Low Carbon Bainitic Steel Held at High Service Temperature

Low carbon bainitic steel derives the high strength mainly from high density of dislocations rather than carbon and alloy element content, so it tends to evolve into equilibrium microstructure with low density of dislocations under thermal disturbance. In the present investigation, granular bainite and lath-like bainitic ferrite were produced respectively in Mo-free low-carbon steels by changing cooling rate. It has been found that granular bainite possesses a lower strength at room temperature than bainitic ferrite, but it exhibits a slower decrease of strength with temperature increasing. Dislocation density in both granular bainite and bainitic ferrite decreases via recovery and recrystallization at high temperature.However, when reheating of bainite is carried out at temperature below 600 °C, a long time will be needed for incubation of recrystallization, during which the hardness of bainite maintains stable. The property makes bainite, especially granular bainite, become a potential microstructure for matrix of high strength fire-resistant steel.     

高温封严涂层材料的基本性能研究与评价

为了提高飞机发动机用封严涂层的使用温度,适应发动机的迅猛发展,对能够在高温条件下使用的封严涂层材料进行了研究,自行设计制备了可磨耗封严涂层团聚粉末材料,使用等离子喷涂工艺成功制备了P7268涂层,随后对研制的在1 000℃以上环境使用的高温封严涂层P7268的基本性能进行探讨,并对涂层在1 000℃的高温稳定性和1 000℃～室温抗热震性能进行了试验.测试发现,P7268涂层在所测试温度具有良好的高温稳定性,具有较小的硬度变化,并且涂层的抗热震性能可以达到耐冷热循环50次.     

高强度高导电率Cu－Cr－Zr－Mg合金的熔炼

介绍了高度高导Ｃｕ－Ｃｒ－Ｚｒ－Ｍｇ合金各元素的基本作用、熔铸特性、熔炉选择、对原材料的基本要求以及为保证合金铸件具有优良的冶金质量制定的原则工艺     

Influence of coating thickness and temperature on mechanical properties of steel deposited with Co-based alloy hardfacing coating

Hardfacing is widely used to improve the performance of components exposed to severe service conditions. In this paper, this surface modification was evaluated for heat-resistance steel DIN X45CrSi9-3 deposited with Co-based alloy Stellite 12 by the plasma-transferred arc welding (PTAW). The microscopic properties of the deposition coating, including the microstructure, the chemical phases, and the distribution of element, were first characterized by optical microscopy (OM), scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), and X-ray diffractometer. To clarify the static mechanical degradation due to the decrease in coating thickness and the increase in temperature, the Vickers hardness and the bending strength were then investigated. The measurements of the Vickers hardness on surfaces of coatings with different thicknesses were conducted at room temperature (RT) and the three-point bending tests on specimens with different coating thicknesses were performed at both RT and 500 °C. The failure modes during the bending tests were finally proposed based on the observations of fracture surfaces. Experimental results showed that the decrease in coating thickness from 2.5 mm to 1 mm did not bring about much degradation of both the Vickers hardness and the bending strength, whereas the increase in temperature from RT to 500 °C led to a significant decrease in the bending strength.