表面自纳米化钢铁材料的研究进展

综述了国内外表面自纳米化钢铁材料的研究进展。介绍了表面自纳米化钢铁材料的不同制备方法,并对比分析了国内外4种主要方法的优缺点和工业应用的可行性。从组织特征、力学性能、耐蚀性及扩散性方面总结分析了表面自纳米化钢铁材料的实验室研究成果。最后对钢铁材料表面自纳米化技术的产业化推广前景进行了展望。     

超声波冲击对纯钛单轴拉伸性能的影响

<正>喷丸、喷砂、机械研磨、超声纳米表面改性、旋转超声喷丸及其他表面纳米化处理技术是近年来研究的热点。M.Wen等研究了利用机械研磨技术获得纯钛细晶的方法,S.Dai等通过高能喷丸将纯钛的屈服强度提高了150 MPa。但对于细晶化表面处理后纯钛在加载时变形机理的研究却很少见到报道。为了研究细晶纯钛单轴拉伸变形机理,俄罗斯国立托木斯克理工大学A.V.Panin等采用超声波冲击的方法制备细晶纯钛样品,并进行拉伸试验,借助于透射     

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.     

细晶化技术在钢铁领域中的应用与发展

在寻找新一代钢铁材料的过程中,超细晶化及纳米化技术倍受关注,它也是中国“新一代钢”研究最重要的问题。因为超细晶材料（晶粒尺寸约几个～1000nm）表现出一系列不寻常的物理、化学和力学性能,它包括纳米材料和亚微米材料。“超细晶化及纳米化”是通过进一步细化材料晶粒及夹杂等达到纳米级实现强度翻番目标的首选方案。     

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...     

纯净化和细晶化钢铁材料

本文主要介绍了国内外纯净化和细晶化钢铁材料的发展，钢的纯净化和细晶化对性能的影响规律，以及使钢铁材料实现纯净化和细晶化的技术措施。     

新一代钢铁材料的研究开发现状和发展趋势

阐述了国内外新一代钢铁材料开发的现状,指出了新一代钢铁材料的发展趋势.即:继续坚持细晶化的技术路线,加强复相化的研究,重视材料的使用性能的开发和纳米析出的利用,努力开发与环境协调、友好的新一代钢铁材料,促进钢铁工业和国民经济的可持续发展.     

Ti-6Al-4V钛合金表面纳米化机制研究

借助X射线衍射仪、透射电镜及显微硬度仪等先进仪器,研究了经超音速微粒轰击( SFPB)形变热处理Ti-6Al-4V合金表面自身纳米化晶粒尺寸演化及纳米化机制.研究结果表明:超音速微粒轰击使Ti-6Al-4V合金表面获得了纳米组织,并发生显著的加工硬化,表面显微硬度比基体硬度提高了1倍多;随着SFPB处理时间的延长,纳米结构层厚度不断增加,晶粒尺寸逐步细化,当SFPB处理30 min后晶粒尺寸趋于稳定,在表层形成了晶粒尺寸约为20 nm具有随机取向的纳米等轴晶.Ti-6Al-4V合金表面自身纳米化是由于位错运动、孪晶的形成及交割共同作用的结果;在多方向载荷的重复作用下,在塑性变形区产生了大量的由位错线和高密度位错缠结分割的位错胞,并在位错寨集处产生应力集中,进而形成孪晶;孪晶自身相互交割和位错的滑移相互协调,形成了细小的孪晶和胞状组织;晶胞组织转变为细小多边形亚晶;当孪晶尺寸细化到亚纳米级时,位错的滑移起主导作用,最终通过位锗的湮灭和重组形成了具有随机取向的等轴状纳米晶粒.     

用非晶晶化法制备纳米晶材料

纳米晶材料具有一般固体材料所没有的优异的力学和电磁特性。通常的纳米晶材料为粉末、薄膜或细丝，因其尺度比较小，产业化比较困难。利用非晶晶化的方法可以制备纳米晶带材、丝材和粉末。例如纳米晶磁性材料Ｆｅ－Ｎｂ－Ｃｕ－Ｓｉ－Ｂ、纳米晶强度材料Ａｌ－Ｎｉ－Ｂ－Ｆｅ等已用此法生产。其中纳米晶磁性材料已大量生产，达到实用规模。实验表明，非晶的成分、制备工艺以及随后晶化的方式都影响纳米晶的形成和以后的使用性能。     

高耐蚀耐磨非晶纳米复合涂层的研究进展

总结了近年来以材料的纳米化技术与非晶化技术相结合为手段,通过表面涂层的功能导向设计,在非晶纳米复合涂层材料体系的选择方法和优化设计原则、非晶纳米复合结构形成和使用过程中的热稳定性和耐蚀/耐磨综合性能优异的非晶纳米复合涂层制备技术等方面取得的研究成果,以及在实际装备上获得的示范性应用成果。     

Effects of stress‐ and/or warm peening of AISI 4140 on fatigue life

Using a new system shot peening and/or stress peening in an air blast machine at elevated temperatures is feasible. The effects of conventional shot peening, stress peening, warm peening and stress peening at elevated temperatures on the characteristics of regions close to the surface, on the stability of residual stresses and on the fatigue strength of a quenched and tempered AISI 4140 steel (German grade 42 CrMo 4) are presented. The alternating bending strength is increased by stress peening, warm peening and especially the combination of both compared to conventional shot peening. These effects are due to the residual stresses induced and the stability of the dislocation structure, which is highly affected by strain ageing effects.     

An analysis of residual stress fields caused by shot peening

In this article, the compressive residual stress field (CRSF) introduced by shot peening was studied comprehensively. The 40Cr steel, which is widely applied in industry materials, was used and shot peened under different conditions. The experimental results show that the maximum of compressive residual stress field for a given material is almost the same even under different shot peening techniques and the surface residual stress values are dependent on both the mechanical properties of target materials and peening parameters.     

干喷工艺对高速钢 M42-弹簧钢D6A 金属带锯条性能的影响

通过二元影像测量仪观察锯条干喷处理后的表面压应力、覆盖率、齿尖状况,不磨合锯切GCr15棒材的齿尖崩刃情况和锯切45^#钢和空转疲劳寿命试验研究表面处理干喷砂工艺参数（压缩空气压力0.1~0.4MPa,运行速度4~1m/min）对M42（/%:1.08C,1.5W,9.4Mo,3.8Cr,1.2V,8.0Co）-D6A（/%:0.48C,1.0Mo,1.1Cr,0.1V,0.6Ni）双金属带锯条性能的影响。结果表明,锯条经合适的参数-压缩空气压力0.3MPa和运行速度3m/min,背部表面覆盖率达到100%,干喷后,齿尖形成稳定的圆角,承受切割和振动的冲击力,以提高锯条齿尖的耐磨性,齿部的平均使用寿命提高66%,背部疲劳试验寿命提高45%~70%。     

Room Temperature Case Carburizing of a Ni–Cr–Mo Steel Through Shot Peening/Blasting Techniques

Controlled shot-peening/blasting is an operation which is used largely in the manufacturing industry. An attempt is made to create a case-hardened surface by the shot peening technique on a Ni–Cr–Mo steel. Steel shots with activated carbon powders were introduced at the surface of the samples for different periods of time, i.e. for 5, 10, 15 and 20 min. The microstructure, chemical composition, and hardness were investigated by optical microscopy, SEM, OES, XRF, XRD and micro-Vickers hardness tester, respectively. An effective diffusion of carbon atoms was found in the samples subjected to shot peening for 10 min. and above. However, the hardness values were found to be non-uniform and showed a maximum hardness of 300 HV_0.3 at activated spots. The microstructural studies revealed formation lamellar-shaped cells consisting of nano grains at the shot peened surface. A close observation of these lamellae shows α-ferrite and cementite (Fe₃C) formed by diffusion of carbon into iron at room temperature. XRD results confirmed the formation of Cr₂₃C₆ and Fe₃C by shot peening with activated carbon.     

Improvement of fatigue properties of PM steels by shot peening

Abstract

Shot peening was used for improving the fatigue properties of Fe–2Cu–0·5C PM steel. The steel is generally used for production of high performance sintered parts such as small connecting rods for cooling system compressors. To distinguish the effects of each alloying element, Fe, Fe–2Cu, and Fe–0·5C were also investigated. Optimum shot peening intensities are: 25A for pure iron and Fe–2Cu, 30A for Fe–0·5C, and 35A for Fe–2Cu–0·5C. For these intensities, improvements of the fatigue strengths of the materials investigated are as follows: 31% for pure iron, 48% for Fe–0·5C, 46% for Fe–2Cu, and 38% for Fe–2Cu– 0·5C. From the experimental results it could be concluded that both of the alloying additions, carbon and copper, are contributing to the fatigue strength improvements by shot peening.     

Damage phenomena in lubricated rolling-sliding wear of a gas carburised 0.85%Mo low-alloyed sintered steel: theoretical analysis and experimental verification

The resistance to surface and subsurface damage during lubricated rolling-sliding wear of a carburised low-alloy sintered steel and the effect of shot peening were investigated. The formation of both contact fatigue cracks and of brittle tensile cracks may be predicted by a theoretical model that was experimentally validated. Carburising is effective in increasing the resistance to contact fatigue, but pores in a hard and brittle matrix may act as pre-existing cracks. Shot peening increases the contact fatigue resistance since compressive residual stresses oppose the nucleation of surface cracks.     

残余应力对55SiMnVB弹簧钢疲劳性能的影响

研究了５５ＳｉＭｎＶＢ弹簧钢板疲劳断口特征及裂扩展过程。结果表明，喷丸强化在表层产生的残余压应力可明显提高疲劳抗力，增强裂纹闭合效应，降低裂纹扩展速度。     

Effect of Shot Blasting and Shot Peening Parameters on Residual Stresses Induced in Connecting Rod

This paper investigates the effect of shot blasting and shot peening parameters on residual stresses induced in connecting rod. Compressive residual stresses are induced using shot peening to increase fatigue life of connecting rod. Shot peening is also responsible for increase in surface roughness. Surface roughness is detrimental for fatigue life of the connecting rod. This necessitates shot blasting to reduce surface roughness. Shot peening and shot blasting processes are analysed to find optimum process parameters which will induce required value of compressive residual stress on the surface of connecting rod. Compressive residual stresses induced in the connecting rod specimen have been experimentally measured using X-ray stress analyser. The experimental results have been analysed using grey relational analysis to find optimum values of process parameters for target value of compressive residual stress and surface roughness. The experimental investigation and the analysis of it have resulted in achieving the desired value of compressive residual stress, which is 10.5% higher over the existing connecting rod. Surface roughness also decreases to 3.84 Ra which is 8.5% lesser than specified value to achieve better fatigue life.     

Finite-Element Analysis of the Influence of Edge Geometry on Shot Peening Process

Shot peening involves bombarding the surface of a metal part with small spherical media called shot. It creates a uniform layer of compressive residual stress at surfaces and considerably increases the part life. This study is devoted to an evaluation of the edge (corner) effects in the shot peening process. Geometry variations in metal parts such as edges or corners cause variance in the residual stress profile induced by shot peening. This paper presents the finite-element modeling and scheme that we use to simulate the shot peening process by both single impact and multiple impacts for part geometries with different edge radii. The results achieved show that, after the same shot peening process, a part with a relatively larger edge radius results in a satisfactory residual stress profile which could equal or exceed that expected for a part with a smaller edge radius. The results may enable the automated edge preprocess step for shot peening with an easily machined large radius to reduce cost and improve productivity.     

一种镍基单晶高温合金的再结晶

 研究了喷丸压力和喷丸时间对一种镍基单晶高温合金再结晶的影响。运用再结晶动力学,分析并探讨了喷丸处理后镍基单晶高温合金的再结晶动力学特征。结果表明:在固溶处理条件下,该镍基单晶高温合金很容易发生再结晶。喷丸处理压力越大,再结晶趋势越强。