焦炉阀体破裂原因分析及更换方法

简述了焦炉阀体的工作原理及连接方式,分析了阀体破裂原因及危害,介绍了阀体的更换方法及安全建议。     

包钢重轨钢典型夹杂物研究

文章对比分析了包钢重轨钢不同钢种的铸坯及钢轨的典型夹杂物的组分及形态特征,明确了重轨钢典型夹杂物的组分及形态,并分析了夹杂物来源及成因。     

金属钕的生产与应用

本文综述了我国金属钕生产的主要发展状况。包括金属钕的生产原料 ,工艺及设备 ,生产能力及产量 ,产品品种及质量 ,产品应用及市场 ,并讨论了一些问题 ,提出了一些建议     

钢铁厂煤气及蒸汽发电技术的应用

介绍了典型钢厂煤气及蒸汽的利用情况,分析了煤气及蒸汽发电的方案及主要热力系统,着重介绍了饱和蒸汽发电技术难点和解决方案。     

15架Y形连轧机轧制钛及钛合金线材的工艺研究

阐述了钛及钛合金的塑性变形特性,分析了Y型轧机的结构及孔型系统,提出用15架Y形连轧机轧制钛及钛合金线材。对连轧常数和连轧张力进行理论分析,通过试验研究确定了钛及钛合金线材连轧张力,从而为低成本、多品种的钛及钛合金线材的生产提出了新的思路,为满足航空航天等高科技领域对钛及钛合金线材的需求奠定了良好的基础。     

对高斯定理特性与应用的认识

阐述了高斯定理的意义,指出了场强、通量、及电荷代数和及相关概念,并对高斯定理的普遍性及应用高斯定理求解场强的条件作了说明.     

真空冶金现状及应用前景

本文回顾了真空冶金的历史及发展过程,讨论了它的特点,阐述了几种主要的真空冶金方法及应用,归纳了其主要应用领域,并指出了其发展前景及方向。     

消弧及过电压保护装置的应用实践

简述了消弧及过电压保护装置的结构及工作原理,详细介绍了该装置的特点及应用实践。     

大型电炉污染物控制与减排

从电炉烟气净化系统、电炉钢渣处理及电炉含铁粉尘处理等几个方面论述了国内外电炉污染物控制及减排技术的发展及存在的问题,指出了我国电炉污染物控制及减排的发展方向.     

冶金工程专业校内实习基地建设

阐述了高等本科院校冶金工程专业校内实习基地建设的必要性和可行性。介绍了校内实习基地建设的思路及具体做法。通过基地建设提高了教师对实践教学重要性的认识,调动了学生的学习积极性,强化了冶金工程类本科生工程实践能力及创新能力的培养,改革了实践教学体系及内容,加强了实验室硬件及软件建设。实践证明,基地的建设收到了良好的教学效果。     

Surface Nanocrystallization of Nb-Ti Stabilized 439M Ferritic Stainless Steel

A new nanocrystallization process was designed, which included punching the surface coating to generate dislocation network or cells and recovery treatment to turn the dislocation cells into nano-sized grains. The effort was made to increase the service life of Nb-Ti stabilized 439M stainless steel surface with medium passive ability, particularly to enhance the outmost surface layer by nanocrystallization for improving resistances to corrosion. Electrochemical properties, electron work functions （EWFs）, nano-mechanical properties of the nanocrystallized surfaces were investigated. It was demonstrated that the nanocrystallized 439M stainless steel surface exhibited improved resistance to corrosion in 0.5 mol/L H2 SO4 solution. However, the nanoci＇ystallized 439M stainless steel surface exhibited decreased resistance to corrosion in 3.5% NaCl solution.     

Nanocrystallization of Amorphous Fe73. 5 Cu1 Nb3 Si13. 5 B9 Irradiated by Laser

The surface nanocrystallization of amorphous Fe73.5 Cu1Nb3Si13.5B9 radiated by CO2 laser was studied by means of M（oe）ssbauer spectroscopy, transmission electro iroscope and X-ray diffraction. The result shows that under certain technical conditions, nanocrystalline is fiound on the surface of amorphous Fe73.5 Cu1Nb3Si13.5B9 radiated by laser; the crystallization phase is α-Fe（Si） crystalline, and its size is about 10-20 nm; the nanocrystalline is uniformly distributed on amorphous base to keep the amorphous and crystallized phase in balance; the a mount of crystallization reaches 23% when the laser power is 300 W, the diameter of light spot is 20 mm, and the radiation speed is 20 mm/s. The phase balance can be controlled by adjusting the laser technology parameter. Laser radiation on the amorphous Fe73.5 Cu1Nb3Si13.5B9 alloy is an important technique for surface nanocrystallization of the amorphous alloys.     

钢铁材料的表面纳米化

表面纳米化技术能通过往复加载使钢铁材料表面发生强烈塑性变形而实现纳米化,在表面形成纳米-微米梯度结构。这种独特的结构既能为研究形变诱发的纳米化机理和宽尺寸范围内结构与性能关系提供理想样品,又能显著地提高钢铁材料整体的综合性能和服役行为,因此可望在工业上取得实用。表面纳米化因丰富的学术和应用价值得到国内外广泛关注,并已成...     

不锈钢的纳米化工艺及其耐腐蚀性

叙述了不锈钢表面纳米化技术-表面机械研磨处理,喷丸法,异步轧制法和激光表面融熔法和不锈钢块体纳米化技术-机械合金法,惰性气体凝聚原位加压法,电化学沉积法,非晶晶化法和大塑性变形法.纳米化不锈钢的耐蚀性能直接受到纳米晶结构的影响,结构均匀,无位错,无应力是获得优异耐蚀性的前提.     

冷轧IF钢表面纳米化后的组织与性能

利用机械研磨处理（SMAT）在冷轧IF钢表面制备出具有纳米晶体结构特征的表面层．利用金相观察和透射电镜分析研究了表面纳米层的结构特征，测定了硬度沿厚度的变化，并分析了表面纳米化（SNC）对力学性能的影响．结果表明：（1）表面机械研磨处理后，冷轧（CR）IF钢表面形成了平均晶粒尺寸为7～9nm、晶粒取向呈随机分布的纳米晶组织；（2）表面层附近的硬度显著提高；（3）纳米表层的存在使得材料强化的同时成形极限也得到提高．     

表面纳米化对低碳钢在干摩擦条件下摩擦磨损性能的影响

采用表面机械研磨的方法对低碳钢板材进行表面处理.经X射线衍射及透射电镜分析表明处理后的试样形成了一定厚度的具有纳米晶粒结构的表层.用立式万能摩擦试验机研究处理后试样在干摩擦条件下的摩擦磨损性能,通过分析其磨损表面形貌,探讨表面纳米化对低碳钢磨损行为的影响.结果表明在载荷为15～75N条件下,其摩擦系数较未处理样品明显降...     

Effect of Surface Mechanical Attrition Treatment on Fatigue Lives of Alloy 718

The effect of surface mechanical attrition treatment (SMAT) and its duration on fatigue lives of alloy 718 has been studied. The SMAT process was carried out in vacuum (?0.1?MPa) with SAE 52100 steel balls of 5?mm diameter for 30 and 60?min at a vibrating frequency of 50?Hz. SMAT resulted in surface nanocrystallization, higher surface roughness, higher surface hardness, higher compressive residual stress, higher tensile strength, reduced ductility and superior fatigue lives. The enhancement in the fatigue lives of treated samples can be attributed to the positive influence of nanostructured surface layer, compressive residual stress and work hardened layer, which surpassed the negative effect of increased surface roughness. There was no significant difference between the fatigue lives of samples treated for 30 and 60?min.     

A multi-scale grained microstructure of the surface nanocrystallized 304 stainless steel sheets after warm-rolling

An ultrafine grained microstructure was obtained for 304 stainless steel(304SS)sheets by using surface nanocrystallization and warm-rolling.The microstructure and mechanical properties were determined by X-ray diffraction(XRD),transmission electron microscope(TEM)and a test on microhardness.Experimental results were shown that the microstructure was featured by a continuous distribution from the nanocrystalline on the surface to micro-grains in the center,in which the volume fraction of the micro-sized grains is about 40% in the surface layer.This multi-scale grained microstructure was composed of austenite and martensite phases with a gradient increasing volume fraction of austenite from the surface to the centre.The microhardness of the resultant steel was higher than 150% of that as received,due to the refined grains and strain-induced martensitic transformation.The hardness distribution was consistent with the microstructural variation,suggesting a good combination of high strength and improved ductility.     

Surface nanocrystallization in AISI 52100 steel induced by surface mechanical grinding treatment(SMGT)

Surface nanocrystallization(SNC) has proved to be an effective approach to improve the overall properties of bulk metallic materials.Recently,a new surface nanocrystallization technique,i.e.,surface mechanical grinding treatment(SMGT),was developed.In this work,a gradient nano-micro structure was achieved in the surface layer of the AISI 52100 steel by using SMGT.We obtained a minimum grain size of about 7nm in the top surface layer.The total thickness of the deformed layer is over 200 micrometer.Meanwhile the surface roughness is rather low. Ferrite grains were deformed to different extents varying with depth from the top surface.Gradient grain sizes were formed from top surface to deep matrix which offered a great opportunity to study the refinement process of the ferrite grains.It is found that dislocation activities play a dominant role in the process.At the initiate stage, dislocations accumulated and interacted to form dense dislocation walls and cells.Increasing strain and strain rate induced more dislocation walls in cells,forming finer cells.This procedure continued until nanograins formed at the top most surface. The existence of cementite particles in ferrite matrix greatly facilitates the ferrite refinement process.Boundaries between ferrites and cementites offered many dislocation sources which accelerate the propagation of dislocations. Dislocation walls were blocked by cementites which certainly lead to finer dislocation cells.The existence of cementites makes it easier to generate fresh dislocation walls in sub-micron grains.A strain gradient was formed from a cementite particle to surrounding ferrite grains.This strain gradient gives rise to more geometric necessary dislocations. As ferrite grain size decreased less than that of cementite particles,fragmentation occurred in cementites.Hard second phase was usually considered as brittle.In this work,evidences of deformation(traces of dislocation activities) in cementites were distinct.Since the stress concentration in the phase boundary(especially triple junction) excesses the shear modulus of cementite,dislocation emission was triggered.It is found in this work that dislocations tend to slip along parallel planes,possibly on(001),(01 0),(100),(110),(10 1 ) and(011) planes,depending upon as the load directions.