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991.
针对洛河大桥加固钢梁所用的Q345qE钢进行焊接分析和研究,对各种焊接接头和焊接方法进行了焊接工艺评定试验,确定其预热温度和焊接工艺.各项性能试验结果表明,所用焊接材料匹配合适,焊接工艺参数合理,各项力学性能指标满足设计和相关规范要求,不但提高了焊接接头的低温冲击韧性,还有效保证了韧强比,使产品焊接接头有良好的抗脆断性... 相似文献
992.
折叠箱内铰链是折叠箱中较关键的部件,一直采用钢板割焊生产,材料利用率低,工序多,成本高.为提高生产效率,降低成本,折叠箱生产厂家决定采用铸造方法生产.根据内铰链的工况要求,需开发出一种低成本、高屈服强度的焊接结构钢生产内铰链.参照焊接结构钢化学成分的要求,设计较低的贵重金属Cr、M0、Cu含量,并通过870℃油淬及580℃的回火热处理,材料达到了折叠箱内铰链铸钢件的要求,即焊接性能好,屈服强度≥390MPa,而且有较好的韧性.生产加工后的内铰链铸件产品完全满足使用要求,内铰链的生产完全可以由铸件生产代替钢板割焊生产. 相似文献
993.
多元低合金耐磨钢的热处理工艺 总被引:1,自引:0,他引:1
研究了一种新型Mn-Cr-Mo-Ni-Cu-RE多元低合金耐磨钢的热处理工艺,利用热膨胀实验测量试验钢的Ae1、Ac3、Ms、Mf等相变温度,借助光学显微镜、扫描电镜、透射电镜等手段,研究了钢的显微组织和断口形貌,测量力学性能,考察热处理工艺对钢的力学性能的影响.研究结果表明,试验钢的相变温度为Ac1=770℃、Ac3=820℃、Ms=340℃、Mf=265℃,经900℃淬火及230℃回火后获得贝/马氏体复相组织,试验钢具有良好的综合力学性能、高强度和高韧性,其硬度达到HRC 52,冲击韧度αKU达到40 J·cm-2. 相似文献
994.
995.
In this study, poly(methyl methacrylate) (PMMA)/starch composites were prepared by a simple solvent casting method. The morphologies of the PMMA/starch composites were studied by scanning electron microscopy. The intermolecular interaction between PMMA and starch was investigated with Fourier transform infrared spectroscopy. The thermal properties of the PMMA/starch composites were compared with those of the pure PMMA sample. Thermogravimetric analysis showed that the thermal stability increased as the starch content increased in the composites. The biodegradability of the PMMA/starch composites was studied with a soil burial test. The degradability was measured in terms of mechanical strength, which increased as the starch content increased. The essential work of fracture (EWF) of the PMMA/starch composite films was investigated by the application of EWF theory under in‐plane (mode I) conditions, and we found that the toughness, in terms of the EWF of composites, increased compared to that of pure PMMA. The fracture of the composites was also evaluated by ANSYS software, and the results were compared to the experimental output. The increased toughness of these PMMA/starch composites may enable their application in the automobile and packaging industries. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
996.
Novel compatibilized polyoxymethylene/thermoplastic polyurethane (POM/TPU) blends are successfully developed using multifunctional chain extender, Joncryl ADR‐4368, as the compatibilizer. The outstanding compatibilization efficiency of Joncryl on POM/TPU blend was demonstrated by its even higher mechanical properties with only 0.5 wt % of Joncryl than those with 5 wt % of three commonly used compatibilizers. Addition of only 0.5 wt % Joncryl can double the impact strength and significantly improve its tensile strength and flexural strength for POM/TPU (75/25) blend. SEM images show that Joncryl can reduce TPU particle size and enhance the interfacial interactions between POM and TPU. The interparticle distance of TPU in POM/TPU/Joncryl blends was calculated as 0.2 μm, quite close to the critical matrix ligament thickness of POM/TPU blends (0.18 μm). The impact force profile vividly shows that the addition of Joncyl in POM/TPU blends can dramatically increase the total impact energy absorbed by this blend system and enhance the interfacial interactions between POM and TPU. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
997.
A numerical 2-D study of the symmetrical 90°-peel test (a similar geometry to the T-peel test) in which extensive plastic deformation occurs in the adherends is presented in this paper. A traction-separation relation is used to simulate failure of the interface, and the conditions for both crack initiation and steady-state crack growth are investigated. The numerical predictions for the steady-state peel force are compared with those based on elementary beam theory. It is shown that two competing effects dominate the mechanics of the peel test to such an extent that the results of beam-bending analyses cannot be used to predict the peel force. At one extreme range of parameters, delamination is driven by shear rather than by bending, resulting in a lower peel force than would be predicted by beam-bending analyses. At the other extreme, where delamination is bending-dominated, the constraint induced by the interfacial tractions cause an increase in the peel force. The numerical results are compared with the results of experiments in which adhesively-bonded specimens are tested in the symmetrical 90°-peel configuration. Excellent agreement between the numerical and experimental results validates the numerical approach. 相似文献
998.
999.
通过对Q390GJD-Z25钢板冲击韧性进行分析,研究了取样方式、试验条件对钢板冲击功的影响。结果表明,钢板厚度方向1/2处的贝氏体组织对低温冲击韧性有明显的影响,焊接接头热影响区的组织不均匀性可恶化钢板的冲击韧性。 相似文献
1000.