振动环境中镁/珍珠岩复合材料的阻尼性能研究

利用真空浸渗法制备了镁合金/珍珠岩复合材料,并利用DTM-Ⅱ-X型动态弹性模量阻尼内耗分析仪在共振条件下测试了其杨氏模量及阻尼内耗值,分析了其阻尼机理。试验结果表明,镁合金/珍珠岩金属基复合材料的阻尼性能要大大优于基体金属的。     

薄板坯连铸连轧65Mn钢的热轧组织与力学性能

利用光学显微镜,扫描电子显微镜(SEM),透射电子显微镜(TEM)和拉伸试验机,硬度仪分析薄板坯连铸连轧工艺CSP生产的高碳高强度钢65Mn的热轧板微观组织与力学性能。该钢主要由珠光体和少量多边形铁素体组成,珠光体片层间距在0.2~0.5μm之间。该钢的平均屈服强度为489MPa,硬度为HRC22.3,伸长率达到18%;没有明显的C和Mn元素偏析,力学性能分布均匀。通过与传统连铸工艺生产的65Mn钢热轧组织与力学性能对比,CSP工艺生产的65Mn钢的组织更加细小,性能更加优良和均匀。     

Is plastic flow always controlled by dislocation mobility? An answer from in situ transmission electron microscopy straining tests

In situ transmission electron microscopy (TEM) straining experiments are used to illustrate in two extreme cases the possible role of dislocation nucleation and exhaustion as a controlling factor in plastic flow. In the first example (FeAl intermetallic compounds), a thermally activated dislocation exhaustion is responsible for an anomalous stress–temperature dependence and an associated small strain rate sensitivity, the latter being evidenced during in situ experiments through unstable localized slip. The second example (heavily drawn pearlite) shows specific dislocation loop nucleation processes that may account for the Hall–Petch law breakdown characteristic of fine scale nanostructures.     

球墨铸铁金相图象的微机分析

阐述球墨铸铁微机分析的原理、操作方法及注意事项。     

硅,锰含量对10SiCrNiCu钢冲击转变温度的影响

研究了Ｓｉ、Ｍｎ含量对１０ＳｉＣｒＮｉＣｕ钢综合性能的影响。研究结果表明：Ｓｉ含量从０．９５％降低到０．４０％～０．７０％、Ｍｎ含量从０．６５％提高到１．３０％,钢的强度指标满足σｓ≥３９０ＭＰａ的设计要求,冲击转变温度明显降低,在低温下,能够表征材料抗脆断能力之一的裂纹扩散功显著提高。     

定量金相分析技术在球墨铸铁金相检验中的应用

对于球墨铸铁的金相检验,传统分析方法是运用GB／T9441—1988中的标准图片采用对比法进行评定的,评定时带有很大的主观性。介绍了定量金相分析技术,它是建立在计算机技术和模式识别技术上的一种新的金相分析技术,可实现定量计算,其操作简单,结果准确,避免了人为误差。     

珠光体共析转变对碳化物粒状倾向的影响

采用热模拟技术研究GCr15轴承钢经不同温度共析转变,得到不同片层间距珠光体组织对接下来的保温过程中碳化物粒状倾向的影响。结果表明:通过降低共析转变温度得到了细小的珠光体组织,随着珠光体球团直径和片层间距的减小,经过相同保温处理后试样显微硬度减小,碳化物呈粒状倾向增大,在500℃共析转变后得到碳化物片层熔断的退化状态珠光体,碳化物的粒状倾向最大。     

Effect of Ultra-Fast Cooling on Microstructure of Large Section Bars of Bearing Steel

The ultra-fast cooling technology of large section bars and the microstructure for different cooling patterns were studied by optical microscope, transmission electron microscope and energy spectrometer. The results indicated that the large section bars were passed through the zone of secondary carbide precipitation quickly by ultra-fast cooling technology (UFC) at instantaneous cooling rate of about 200 ℃/s and the finishing cooling temperature was higher than M,. The lamellar spacing of pearlite decreased and the microhardness increased with decreasing the re-reddening temperature. The precipitation of network carbide was restrained when rereddening temperature was 690 ℃. And fine laminated pearlite was obtained through transformation of pseudopearlition that induced the reduction of the diameter of pearlite grain and refinement of the lamellar spacing of pearlite, so ideal microstructures of promoting spheroidizing annealing were obtained.     

钢表面片状珠光体分数维计算

利用多媒体计算机扫描金属相谱中含碳量不同的钢表面的图片,运用图形处理软件Photoshop等工具处理图片,从表面分形Hausdorff-Besicovitch维数确定的方法出发,确定含碳量不同的钢表面片状珠光体的分数维数值,并利用计算机将一个正方形等分为25个正方形,分别保留10,15和19块,在保留的正方形中继续进行相同的操作,最后形成的分形,其维数是1.431,1.683和1.829.分别与20号钢,40号钢和60号钢表面片状珠光体维相同。     

合金元素Si—Al—Cr对铸铁高温腐蚀性能的影响

论述了合金元素Si、Al、Cr的耐高温腐蚀性能,上述三种元素在高温下形成氧化膜的PB比在1－2间,电导率较小和较少的晶格缺陷,并且具有良好的热力学稳定性,可起到很好的高温防护作用,是耐热铸铁的首选元素。