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...     

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。     

钢铁材料的晶粒细化研究

回顾了最近几年来在钢铁材料晶粒细化方面取得的一些研究成果，叙述了钢铁材料晶粒细化的目的与晶粒细化理论，阐述了目前常用的几种晶粒细化方法（微合金化、形变诱导相变、形变热处理等）的理论依据、适用条件、应用情况以及存在的问题，为今后材料科学工作者研究钢铁材料晶粒细化以及实际工程应用提供参考。     

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。     

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。     

国内外超细晶钢铁材料研究进展

介绍了几种常用的晶粒细化方法,包括微合金细化法、电磁场细化法、纳米析出相细化法、应变诱导相变和形变强化相变,分析了超细晶材料在开发和应用中存在的问题,为钢铁材料晶粒细化的研究及实际应用提供参考。     

钢铁材料晶粒的超微细化（日）

阐明钢铁材料晶粒超微细化的发展状况，详细介绍了利用钢中各种相变的最后的热机械处理以及利用适当的回复和再结晶现象的强烈变形得到超细晶粒钢的两种方法，汇集了超细晶粒钢的显微组织特征和机械性能，讨论了超细晶粒钢的未来发展和前景。     

表面纳米晶化处理中碳钢的组织与力学性能

采用高能表面处理技术在40Cr钢的表面制备出具有纳米晶体特征的表面层.用扫描电子显微镜和透射电子显微镜研究了表面纳米层的微观结构,并利用纳米压入法测定了表面纳米层的硬度.结果表明,经过高能表面处理后,样品表面层的晶粒细化为纳米晶,平均晶粒尺寸约为11 nm,表面纳米层的硬度明显提高.     

凝固过程中质点强化钢铁材料的研究进展

新一代钢铁材料的主要特征是高洁净度、超细晶粒和高均匀化,金属材料组织的晶粒细化处理是能同时提高材料强度和韧性的最佳强化机制。简述了钢铁材料在凝固过程中晶粒细化的方法、应用情况以及存在的问题。     

应变诱发铁素体相变对低碳钢晶粒细化的影响

研究了在奥氏体低温区变形时显微组织的变化,并测试了其变形抗力。结果表明：在Ar3以上温度变形会产生应变诱发铁素体相变,使变形抗力下降。通过降低变形温度,铁素体晶粒得到细化。     

Upgrade Rolling Based on Ultra Fast Cooling Technology for C-Mn Steel

By measuring the expansion curves of a C-Mn steel at different cooling rates by using an MMS-300 thermo- mechanical simulator, continuous cooling transformation curves were obtained. The new process ＂ultra fast cooling＋ laminar cooling＂ was simulated and the effects of ultra fast cooling ending temperature on microstructure had also been investigated. The hot rolling experiment was done by adopting ＂high temperature rolling-[-forepart ultra fast cooling＂ technologies at laboratory scale. The results revealed that ultra fast cooling can delay the decrease of disloca- tion density and refine ferrite grains. Diversity control of the microstructure and phase transformation strengthening can be realized by changing the ultra fast cooling ending temperature. With the decrease of ultra fast cooling ending temperature, the strength and toughness increase, but plasticity does not decrease obviously. The new technique can improve the yield strength by over 50 MPa. Therefore, the upgrade of mechanical properties of C-Mn steel can be realized by using ＂high temperature rolling＋ ultra fast cooling＋laminar cooling＂ technique. Compared with ＂low temperature rolling with large deformation degree＂ technique, this new technology can decrease the roiling force and in- crease the production efficiency.     

关于细化低合金钢铁素体晶粒的研究进展

回顾了近十年来低合金钢相变细化铁素体晶粒的进展。在无应变和有应变的条件下,给出了在相变过程中铁素体形核位置和密度的模型。探讨了晶内铁素体的形核机制;Ｖ－Ｎ钢中ＶＮ是优先生核的位置,更主要的是ＶＮ能抑制晶界铁素体的长大。追踪国际上获得超细晶组织的机理和方法,探讨了晶粒尺寸对屈服强度（σｓ）和冲击韧性转折温度（Ｔｃ）的作用,利用应变诱导动态相变机制获得超细晶组织。     

变形工艺对微合金高强度钢组织的影响

在THERMECMASTOR-Z热模拟试验机上进行了一种微合金高强度钢在不同变形程度、变形速率、变形道次和冷却速度等工艺条件下的热模拟实验.分析比较了不同变形工艺参数对微合金高强度钢相变及组织的影响.实验结果表明,提高轧后的冷却速度使Ar3温度降低;变形速率越大相变开始温度越高;变形程度越大相变开始温度越高.增大变形程度,采用多道次轧制,轧后快速冷却,均有助于铁素体晶粒的细化和减少珠光体的含量.实验钢种的γ+α两相区的温度范围大于140 ℃.     

无取向电工钢的生产现状及发展

简要回顾了无取向电工钢的发展历程。重点分析了无取向电工钢生产过程中的难点和重点。分析和论述了无取向电工钢的工艺发展现状与趋势。     

钢铁生产流程发展及先进钢铁材料研究的展望

简要介绍了氧气转炉炼钢、连续铸钢、炉外精炼及控冷控轧技术的特点及优势,指出20世纪中国钢铁工业发展所存在的问题,展望21世纪先进钢铁生产流程中氢冶金、新一代可循环钢铁流程、铸-轧-材一体化技术的实现.在此基础上,介绍先进钢铁材料的研究开发现状.     

超高强铁素体/贝氏体双相钢的控轧控冷

通过实验室热轧机组的控轧控冷试验,研究了控轧控冷参数对超高强铁素体/贝氏体双相钢组织性能的影响。结果表明,采用不同温度终轧,轧后不同方式冷却,抗拉强度几乎都在1 000MPa以上,屈强比在0.54～0.62之间,伸长率在13%～17%之间。铁素体晶粒随终轧温度降低和冷却速度加快而细化;终冷温度降低,贝氏体量增多。经800℃终轧后层流冷却至560℃左右空冷,由于铁素体晶粒细化,组织中大量的粒状贝氏体、无碳化物贝氏体、少量的孪晶马氏体以及残余奥氏体的存在使抗拉强度达1 130MPa,伸长率达16%,强塑积达到18 080MPa.%的最高值。控轧控冷获得以铁素体/贝氏体双相组织为主并含有少量残余奥氏体+马氏体的复相组织,使试验钢具有了优异的力学性能。     

Austenite Grain Refinement by Reverse α′→γ Transformation in Metastable Austenitic Manganese Steel

Microstructure of metastable austenitic manganese steel after reverse transformation treatment was investigated using optical microscopy,X-ray diffraction(XRD),electrical resistivity and hardness testing.Austenite grain refinement was successfully achieved by a two-step heat treatment.First,martensite was produced by cooling the solution-treated samples to-196 ℃.Then,the deep cryogenic treated samples were heated to 850 ℃ upon slow or rapid heating.The mean size of original austenite grain was about 400μm.But the mean size of equiaxed reversion austenite was refined to 50μm.Microstructure evolution and electrical resistivity change showed that martensite plates underwent tempering action upon slow heating,and the residual austenite was decomposed,resulting in the formation of pearlite nodules at the austenite grains boundaries.The refinement mechanism upon slow heating is the diffusion-controlled nucleation and growth of austenite.However,the reverse transformation upon rapid heating was predominated by displacive manner.The residual austenite was not decomposed.The plateα-phase was carbon-supersaturated until the starting of reverse transformation.The reverse transformation was accompanied by surface effect,resulting in the formation of plate austenite with high density dislocations.The refinement mechanism upon rapid heating is the recrystallization of displacive reversed austenite.     

Effect of Hot Torsion Parameters on Development of Ultrafine Ferrite Grains in Microalloyed Steel

 Hot torsion testing was performed on a low carbon Nb-Ti microalloyed steel to study the effects of hot torsion parameters, strain and strain rate, on ultrafine ferrite grains production through dynamic strain-induced transformation, at a deformation temperature just above Ar3. The initiation and evolution of ultrafine ferrite grains were studied. The results show that the amount of strain and strain rate has conversely effect on the volume fraction and grain size of ultrafine ferrite grains. With increasing strain, the interior of austenite grains become activated as nucleation sites for fine ferrite grains. As a result, ferrite grains continuously nucleate not only at the former austenite grain boundaries but also inside the austenite grains which leads to a rapid increase in volume fraction of ultrafine grains. Increasing of strain rate reduces the tendency of ferrite grains coarsening so that ultrafine ferrite grains are achieved, while the volume fraction of ultrafine grains decreases at the same strain level.