碳化物粒子尺寸对裂纹断裂韧性的影响

通过对铁素体晶粒尺寸相同，碳化物粒子尺寸不同的两种低合金风ＣＯＤ裂纹试样断裂韧性的测试，宏微观断口和力学参数的测量，结合断口，金相观察分析，对碳化物粒子尺寸对裂 断裂韧性的影响及其机进行了研究。     

Effect of low-frequency rotary electromagnetic-field on solidification structure of continuous casting austenitic stainless steel

To understand the solidification behavior of austenitic stainless steel in rotary electromagnetic-field, the influence of low-frequency rotary electromagnetic-field on solidification structure of austenitic stainless steel in horizontal continuous casting was investigated based on industrial experiments. The results show that the solidification structure of austenitic stainless steel can be remarkably refined, the central porosity and shrinkage cavity can be remarkably decreased, and the equiaxed grains zone are enlarged by means of application of appropriate low-frequency electromagnetic-field parameters. The industrial trials verify that the stirring intensity of austenitic stainless steel should be higher compared with that of plain carbon steel. Electromagnetic stirring affects the macrostructure even if the average magnetic flux density of the electromagnetic stirring reaches 90 mT (amplitude reaches 141 mT) with the frequency of 3–4 Hz. Due to a higher viscosity, rotating speed of molten stainless steel is 20%–30% lower than that of molten carbon steel in the same magnetic flux density. Foundation item: Project(CSTC2007BB4216) supported by the Natural Science Foundation of Chongqing, China     

Mg-Al4C3中间合金对AZ31B镁合金组织的细化

采用SEM、EDS 和XRD 等测试手段研究Mg-50%Al4C3中间合金对AZ31B 镁合金显微组织的细化效果.研究结果表明,中间合金的加入可显著细化AZ31B镁合金的枝晶组织和晶粒尺寸.当Al4C3的加入量为0.9%时,α-Mg 晶粒的平均尺寸由基体合金的280 μm降至约53 μm.β相由连续网状转变为不连续的网状和细小弥散的粒状.通过能谱分析及面错配度计算证实,Al4C3可成为初生α-Mg晶粒的良好异质核心.     

高强箍筋混凝土简支梁抗剪承载力试验研究

通过对14根500 MPa细晶粒钢筋、1根400 MPa及1根600 MPa钢筋做箍筋的混凝土简支梁在集中荷载作用下的试验,观测了不同混凝土强度、不同剪跨比、不同箍筋强度、不同配箍率、不同截面尺寸条件下试件的裂缝、挠度、承载力及破坏形态;并将实测值与有关公式的计算值进行了比较.试验结果表明,构件的斜截面承载力仍可按现行《混凝土结构设计规范》的相关公式进行计算,并有足够的安全储备.     

45#钢锻件热镦粗过程晶粒尺寸模拟

应用自主开发的镦粗过程锻件组织模拟软件 ,对 45 #钢热镦粗过程中的晶粒尺寸进行了模拟 ,得到了不同压下量下的应变场、应变速率场以及动态再结晶晶粒尺寸的等值线 ,并分析了压下量对各场变量变化规律的影响 .     

勘察阶段深埋长大隧中道煤层瓦斯涌出与突出的预测研究

公路、铁路深埋长大隧道在勘察设计阶段如何进行煤层瓦斯的预测与评价工作,尚无成熟经验.但是,运用瓦斯地质的基础理论和测试方法,结合隧道工程地质特点,在勘察阶段预测煤层瓦斯的涌出与突出,是可行的.煤层瓦斯的涌出与突出,主要与煤层瓦斯含量、压力及影响瓦斯赋存的地质因素有关.作者在勘察阶段着重进行地质因素调查、分析,并采用地勘阶段适用的测试方法,建立了瓦斯突出的综合判据,初步建立了勘察阶段瓦斯地质工作的思路与方法.     

Electron theory study on the effect of Mn on as-cast structure of Fe-C-Cr-Mn cast irons

The valence electron structure of alloying austenite of 3C-15Cr high chromium white cast iron with different Mn contents from 1% to 6% is analyzed by BLD method and EET. Results show that the addition of Mn has major influence on the valence electron structure of the alloying austenite, especially on that of Fe-C, Fe-C-Cr and Fe-C-Cr-Mn unit cells of it. The effect becomes weak when Mn content is over 4%. Based on the effect of n~, F~~, the weighting of each unit cell and the degree of undercooling on phase transition of the aus- tenite, we can calculate the retained austenite content of as-cast structure of the high chromium white cast iron. The calculation results coincide well with those of the experiment. The phase transition characters of the austenite in high chromium white cast iron can be forecasted through valence electron structure analysis of alloying austenite by BLD method and EET on the basis of Fe-C-Cr equilibrium phase diagram.     

S枪磁控溅射Ni薄膜晶粒结构与导电特性的研究

应用薄膜晶粒边界散射的三维物理模型,分析了Ｎｉ薄膜晶粒结构对Ｎｉ薄膜电阻特性的影响,采用正交试验法得到了Ｓ枪磁控溅射的Ｎｉ薄膜具有良好导电特性的最佳工艺条件。ＳＥＭ照片表明了不同工艺条件下Ｎｉ薄膜的薄膜晶粒结构,最后给出了Ｓ枪磁控溅射的Ｎｉ薄膜制成的温度传感器的电阻温度特性。     

均匀沉淀法制备超微细透明氧化铁黄颜料

以FeSO4和CO（NH2）2为原料，采用均匀沉淀法制备了超微细透明氧化铁黄颜料，讨论了反应条件对产品晶粒大小及分布的影响，得出了优化的工艺条件，FeSO4浓度为1.0mol/L。原料磨尔比n[尿素]；n[Fe^2 ]=3.5:1，空气通入量6L/h，复合添加剂用量0.3%。     

武钢自制冷轧工作辊质量分析及改进

分析武钢自制冷轧工作辊质量事故，发现自制冷轧工作辊存在一种少见的剥落形态，对剥落工作辊取样，并就其化学成分，金相组织，微观断口进行检测，分析表明：粗针状马氏体组织及高含量的残余奥氏体相是引起轧辊内部裂纹的主要原因。自制冷轧工作辊的这种剥落是由内部裂纹所致。