低碳贝氏体钢20SiMnMo的摩擦焊接性研究

研究了低碳贝氏体钢２０ＳｉＭｎＭｏ在不同的摩擦焊接工艺参数下的组织和性能，探讨了热处理回火温度对焊接接头强度和韧性的影响，优化了低碳贝氏体钢的摩擦焊工艺参数和热处理规范参数     

DC potential drop method for evaluating material degradation

The remaining life estimation for the aged components in power plants as well as chemical plants are very important because mechanical properties of the components are degraded with in-service exposure time in high temperatures. Since it is difficult to take specimens from the operating components to evaluate mechanical properties of components, nondestructive techniques are needed to evaluate the degradation. In this study, test materials with several different degradation levels were prepared by isothermal aging heat treatment at 630°C. The DC potential drop method and destructive methods such as tensile and fracture toughness were used in order to evaluate the degradation of 1Cr-1Mo-0.25V steels. In this result, we can see that tensile strength and fracture toughness can be calculated from resistivity and it is possible to evaluate material degradation using DC potential drop method, non-destructive method.     

Influence of steel fibres on strength and ductility of normal and lightweight high strength concrete

This paper presents the results of a series of experiments conducted to investigate the effectiveness of fibre inclusion in the improvement of mechanical performance of concrete with regard to concrete type and specimen size. Lightweight aggregate concrete and limestone aggregate concrete with and without steel fibres were used in the study. The compressive strength of the concrete mixes varied between 90 and 115 MPa and the fibre content was 1% by volume. Splitting tests on prisms and three-point bending test on notched beams were carried out on specimens of varying sizes to examine the size effect on splitting strength, flexural strength and toughness.

The experimental findings indicate that the low volume of fibre has little effect on compressive strength but improve remarkably splitting tensile strength, flexural strength and toughness. The increase in splitting tensile strength, flexural strength and toughness index for lightweight concrete seems much higher than that of normal aggregate concrete.

The size effect on prism splitting tensile strength is not significant beyond a critical (transition) size. There are apparent size effects on flexural strength and toughness index. As the specimen size increases, splitting and flexural strengths appear to decrease, and fracture behaviour tends to be more brittle.     

Characterisation and modelling of toughness in 6013-T6 aerospace aluminium alloy friction stir welds

The effect of the friction stir welding process on the toughness properties of AA6013-T6 sheet has been investigated. The alloy was received and welded in the peak aged T6 condition and the toughness measured at intervals across the weld by means of a notched tear test, with subsequent fractographic examination via field emission gun scanning electron microscope (FEGSEM) and microstructural characterisation via optical microscopy and energy dispersive X-ray (EDX). It is shown that the controlling factors for toughness in AA6013-T6 following FSW are the population and distribution of the coarse α-(Al,Fe,Si,Mn) intermetallic particles, with strength variations caused by precipitate dissolution, coarsening and transformation representing a secondary consideration. Minimum toughness occurs at the boundary between the weld nugget and the heat-affected zone due to the alignment and concentration of coarse particles at this point by the FSW process. A simple model is implemented and provides a reasonable prediction of the weld toughness from simple microstructural observations.     

影响球墨铸铁曲轴质量的因素

通过对失效的球墨铸铁曲轴的分析和统计,认为造成球铁曲轴断裂失效的主要因素有铸态下存在孔洞类缺陷、等温淬火态时组织脆性较大和正火态时圆角不强化,而曲轴磨损失效的主要因素是润滑不足。提高等温淬火组织的韧性和强化曲轴圆角是防止曲轴断裂失效的主要措施。     

Toughening of Epoxy Resin with Solid Amine Terminated Poly （ethylene glycol） Benzoate and Effect of Red Mud Waste Particles

An investigation was carried out to modify the toughness of triethylene tetramine cured DGEBA （diglycidyl ether of bisphenol-A） resin using solid amine terminated poly （ethylene glycol） benzoate （ATPEGB） as modifier with and without red mud waste particles. The solid ATPEGB modifier synthesized from the acid catalyzed esterification reaction of poly （ethylene glycol） （PEG） and 4-amino benzoic acid was characterized by Fourier transform infrared spectroscopy （FT-IR） and ^1H-NMR （nuclear magnetic resonance） spectroscopies, viscosity measurements, and solubility parameter calculation. The unfilled and red mud waste filled modified epoxy networks were evaluated with impact, adhesive, tensile, flexural and thermal properties by differential scanning calorimetry （DSC）, thermogravimetric （TG） and dynamic mechanical analysis （DMA）. The effect of modifier concentration and red mud waste particles on toughening behavior was also investigated. The optimum properties were obtained at 12.5 phr （parts per hundred parts of resin） concentration of the modifier. The ATPEGB modified cured epoxy was thermally stable up to 315℃. The morphology on fracture surfaces of cured epoxy was also analyzed by scanning electron microscopy （SEM）.     

增强体颗粒预氧化对AlCuMgAg基复合材料强度与韧性影响

预先对增强体颗粒进行表面氧化处理,然后采用压铸浸渗法制备了体积分数为50％的SiC颗粒增强AlCuMgAg基复合材料。通过力学性能测试与扫描电镜观察,研究了SiC颗粒表面氧化处理对复合材料抗拉强度与韧性的影响。结果表明,适度的预氧化可以提高基体与颗粒之间的界面结合强度,使复合材料抗拉强度得到提高,但其韧性稍有下降。     

10MnNiCr钢板应变时效敏感性研究

对10MnNiCr钢板进行了应变时效敏感性试验。结果表明,10MnNiCr钢热轧薄板、调质厚板具有较低的应变时效敏感性,而正火+高温回火热处理的10MnNiCr钢中板具有较高的应变时效敏感性。改善钢的微观组织,提高钢的韧性,可降低钢的应变时效敏感性。     

透明PVC／MBS合金的研究

本文对不同型号的ＰＶＣ与ＭＢＳ进行共混改性,通过冲击,应力－应变试验,动态力学分析（ＤＭＡ）、扫描电镜（ＳＥＭ）和紫外可见光谱研究了ＰＶＣ／ＭＢＳ共混体系的性能与形态结构之间的关系。结果表明,用ＭＢＳ改性ＰＶＣ既能有效地提高共混物的韧性,又能保证其具有良好的透光率。     

α、β半水石膏混合粉性能初探

通过α半水石膏和β半水石膏不同配比混合的实验,讨论了混合石膏比,膏水比对其强度、吸水率、凝结时间的影响及相关性能。