室温Φ=120°等径弯曲通道变形工业纯钛的力学性能

采用模角Φ=120°的模具,以BC方式(两次挤压道次之间试样绕纵轴沿同一方向转动90°进行下一道次挤压)在室温下成功实现了工业纯钛8道次等径弯曲通道变形(ECAP),对挤压过程中各道次试样的微观结构及性能进行了分析测试.结果表明:工业纯钛经8道次ECAP变形后,抗拉强度由407 MPa升高到791 MPa;显微硬度由1 588 MPa升高到2 641 MPa;并保持良好的塑性,伸长率为19%.     

等径弯曲通道变形(ECAP)的研究现状及发展趋势

等径弯曲通道变形（equal channel angular processing,ECAP)是使材料经受强烈塑性变形的一种加工方法。本文介绍ECAP的国内外发展概况，对其方法和影响因素等做了概述，并对其应用前景做了进一步的展望。     

变形晶界对低碳钢显微组织的影响

对不同温度下变形和变形后再加热到奥氏体区的低碳钢SS400的显微组织进行了研究，结果表明：变形使奥氏体和铁素体晶界呈锯齿状，锯齿状的奥氏体晶界优先成为铁素体的形核位置，锯齿状的铁素体晶界有利于铁素体再结晶核心的形成。     

板坯加热温度对冷轧超低碳钢组织的影响

板坯加热温度对冷轧超低碳钢组织的影响［俄罗斯］等由于生产的汽车车身冷冲压零件的形状更趋复杂，因此需要有能适合于这种机械加工的各种冷轧钢。现已开发出用有效的碳氮化合物形成元素（用钛和铌）稳定的新一代超低碳钢（＜０．０１％Ｃ）即所谓ＩＦ钢（无自由间隙原子...     

酸溶硼含量对低碳钢组织性能的影响

在特定条件下定量研究了酸溶硼含量对钢材力学性能的影响。通过对比研究发现,每提高1 ppm的酸溶硼含量可以提高22.05 MPa的抗拉强度,29.55 MPa的屈服强度。酸溶硼含量的提高有效提高了钢的各项性能,钢中固溶硼对提高钢的淬透性起到至关重要的作用,改善了钢的显微组织状态,提高了钢的强度和冲击韧性,并且减少了由于BN含量的增加造成的韧性下降。     

原始组织对304L超低碳奥氏体不锈钢等径角挤压变形的影响

304L超低碳奥氏体不锈钢由25kg真空感应炉冶炼,用透射电镜(TEM)研究了该钢铸态组织200℃等径角挤压变形(ECAP)后组织演变和铸态组织1道次ECAP+1150℃1.5 h,AC处理(固溶组织)再进行ECAP后的组织。结果表明,304L钢铸态组织1道次ECAP变形过程中主要的变形机制为滑移变形,同时出现少量的孪晶变形;304L钢固溶组织在ECAP变形过程中孪晶变形数量急剧增加,孪晶和滑移共同进行,细化原始晶粒组织演变。     

热轧低碳钢高温变形行为与显微组织

采用 Gleeble-1500试验机对低碳钢进行热变形试验,获得了真应力-真应变曲线,进而研究了变形温度为900~1200℃,应变速率为0·1~10 s－1对材料热变形行为的影响。通过非线性回归获得了材料在不同变形条件下的材料常数,建立材料的热变形本构方程,进而分析了热变形低碳钢的微观组织演变及极限压缩率的变化规律。结果表明：基于热变形方程真应变为0·5时的热变形激活能Q为216·95 kJ/mol,利用该本构方程计算的峰值应力与试验得到的应力-应变曲线的峰值应力吻合较好;应变速率1 s－1,变形温度1100℃下的显微组织较其他温度相比都要细小、均匀,此时其极限压缩率最大可以达69％,可在此工艺条件下实现较大的塑性变形,且变形后具有较好的综合力学性能。     

FTSR薄板坯连铸连轧0．8mm超薄低碳钢板的组织和性能

利用光学照微镜、扫描电镜和透射电镜等仪器研究分析了采用唐钢薄板坯连铸连轧线（FTSR）试轧的0.8mm厚热轧低碳钢超薄带的显微组织和第二相粒子，并通过实验对其力学性能和成形性能进行了分析研究。研究结果表明：FTSR线生产的0．8mm超薄低碳带钢组织比较细小、均匀．且具有良好的综合力学性能和优良的成形性。     

Sn对超低碳钢显微组织和硫化物析出的影响

Cu和Sn是钢中特别是废钢循环利用时最主要的两个残留杂质元素,硫是钢中的主要杂质,钢脱硫需要排出大量的渣和CO2,对冶金工作者来说利用这些元素是一个重要而困难的问题。本研究在试验室准备了Cu、S和Sn不同含量的铸态钢,研究了加Sn对硫化物析出的影响,讨论了硫化物形态、尺寸和成分。试验结果表明,钢中加Sn抑制硫化物在高温时的析出,在低温下促进更多的Cu结块和使硫化物析出细化。另外,硫化物的析出表现出减小Sn在钢中的偏析程度,可能因为S11溶入硫化物中到一定程度,硫化物粒子提供了分布Sn的更多界面。     

预处理组织对低碳钢IQ&P工艺下组织及性能影响

采用γ单相区和γ+α双相区轧制并淬火工艺以及双相区再加热-淬火-碳配分(IQ&P)工艺,研究预处理组织对低碳钢室温状态多相组织特征及力学性能的影响规律.实验用低碳钢经两种工艺轧制并淬火处理,获得马氏体和马氏体+铁素体的预处理组织,再经双相区IQ&P工艺处理后均获得多相组织.马氏体预处理钢的室温组织由板条状亚温铁素体、块状回火马氏体以及一定比例的针状未回火马氏体和8.2%的针状残余奥氏体组成;马氏体+铁素体预处理钢由板条状亚温铁素体、块状和针状未回火马氏体以及14.3%的短针状或块状残余奥氏体组成.在相同的双相区IQ&P工艺参数下,预处理组织为马氏体的钢抗拉强度为770 MPa,伸长率为28%,其强塑积为21560 MPa·%;而预处理组织为马氏体+铁素体的钢抗拉强度为834 MPa,伸长率增大到36.2%,强塑积达到30190 MPa·%,获得强度与塑性的优良结合.      

ECAP铜基原位复合材料的组织与性能研究

室温下采用等通道变形(ECAP)制备了 Cu-5.7%Cr原位复合材料,研究了其力学性能,电导率以及原位纤维的演变.结果表明:经过ECAP后,第二相Cr发生了旋转和伸长,逐渐演变为细小的纤维,且纤维逐渐倾向于与x轴平行.Cu-5.7%Cr合金的硬度,抗拉强度在2道次前显著增加,延伸率则迅速下降.2道次以后,硬度和抗拉强度的增加缓慢,延伸率则保持在20%左右.随着变形道次的增加,电导率逐渐降低,4道次后趋于稳定,8道次后达到80%LACS.     

Three-Dimensional Microstructures and Tensile Properties of Pure Iron During Equal Channel Angular Pressing

 Commercial pure iron billets having diameter of 60 mm and length of 180 mm were subjected to equal channel angular pressing (ECAP) at 350 ℃ for 1 to 4 passes via route Bc. Microstructural evolutions on three planes (X, Y, Z planes) were characterized by optical microscopy and transmission electron microscopy (TEM). It was found that after four passes an ultrafine microstructure could be formed on the X plane, but a band structure remained on the Z plane. Accordingly, the mechanical properties exhibited apparent dependence on the orientations. The strength in the x and y directions was higher than that in the z direction. The microstructural refinement and mechanical properties were discussed in terms of experimental results.     

铸态304L奥氏体不锈钢等径角挤压变形的力学性能

 研究了经1~4道次等径角挤压变形(ECAP)后,铸态304L奥氏体不锈钢微观结构的演变,同时测定了ECAP变形后的力学性能。结果表明,经4道次变形后,铸态粗大晶粒破碎形成细小的大角度晶粒,平均晶粒尺寸约202 nm;抗拉强度和屈服强度大大提高(Rp02=1 002 MPa,Rm=1 100 MPa),但均匀塑性变形能力(A＜3%)和加工硬化指数(n=0060)却显著下降。     

Microstructure and Properties of Ti and Ti+Nb Ultra-Low-Carbon Bake Hardened Steels

Hot rolling, cold rolling and continuous annealing processes of Ti bearing and Ti+ Nb stabilized ultra-low-carbon bake hardened steels were experimentally studied. The microstrueture and texture evolution, as well as the morphology, size and distribution of second phase precipitates during hot roiling, cold rolling and continuous annea-ling were also analyzed. The results showed that the size of NbC precipitates in Ti+ Nb stabilized ultra-low-carbon bake hardened steel was smaller than that of TiC precipitates in Ti bearing ultra-low-carbon bake hardened steel, which made the average grain size of Ti+ Nb stabilized ultra-low-carbon bake hardened steel finer than that of Ti bearing ultra-low-carbon bake hardened steel; for the yield strength, the former was higher than the latter; but for the γ value which reflects the deep-drawing performance, the former was lower than the latter.     

铸态304L奥氏体不锈钢等径角挤压变形研究

 研究了铸态304L奥氏体不锈钢在等径角挤压(ECAP)变形过程中显微组织的演变过程。结果表明,经4道次剪切变形后树枝晶破碎、原始粗大晶粒碎化。显微组织的变化过程可归纳为：原始粗晶粒→晶粒被滑移带分割→位错发展形成高密度位错墙,与滑移带共同作用形成胞块结构→应变增加形成层片状界面→形成大角度晶界的细小晶粒。表明铸态304L奥氏体不锈钢经ECAP变形后塑性变形机制主要由滑移完成。     

含钛超低碳搪瓷钢板的退火工艺

 研究了两种不同退火工艺——罩式退火和连续退火工艺对含钛超低碳搪瓷钢板成型性能和贮氢性能的影响。试验结果表明,材料经连续退火后其成型性能略优于罩式退火,而其贮氢性能是经罩式退火后的明显好于连续退火。因此综合考虑,采用罩式退火工艺可实现成型性能和贮氢性能的良好匹配。     

ECAP过程中TWIP钢的组织演变

 研究了 TWIP钢（30Mn-3Si-3Al）在等径角挤压冷变形过程中的组织演变。试验结果表明：经1道次变形后,产生大量10～40 nm宽的形变孪晶,同时出现的微观剪切带对孪晶进行了切割。随着道次的增加,孪生系统增多,形变孪晶相互交割,孪晶板条出现弯曲和断裂;同时剪切带的数量和宽度都增加,产生相互交错并切割孪晶板条,使基体的细化面积增大。4道次变形后,组织变成由碎化带和割裂开的孪晶相互交织的变形结构。碎化部分超细晶晶粒尺寸为40～120 nm,而未碎化孪晶板条宽度降至5～20 nm。     

Effect of Equal Channel Angular Pressing on Microstructure and Mechanical Properties of Commercial Purity Aluminum

Commercial purity aluminum was deformed by equal channel angular pressing (ECAP) using steel dies producing two different shear strains of either 1.15 or 0.60 in each pass. Two sets of samples were selected for study, of which the first set consists of aluminum billets repeatedly deformed without changing orientation (process A) up to three passes using first die. The second set of samples was equal channel angular pressed (ECAPed) using the second die up to 10 passes adopting process B_c, where samples were rotated by 90 deg between successive passes. The flow patterns were revealed by optical metallography. Tensile strength and hardness were measured. The ECAPed samples were isochronally-annealed and recrystallization behavior was studied by microscopy and Vickers hardness measurements. Refinement of grain size, substructure, and texture was studied by transmission electron microscopy (TEM) and orientation imaging microscopy (OIM). The results show that flow patterns are complex and distinct from simple shear. Strain is higher at the outer surfaces, highest at the bottom surface, and intermediate in the middle of the billet. The work piece strain hardens significantly in first pass with an attendant drop in ductility. The degree of strengthening reduces in subsequent passes. The high defect density introduced during the initial passes leads to grain refinement to an ultrafine level and advantageously the material regains ductility. The refinement in microstructure obtained after two to three passes is stable up to 250 °C. The flow patterns are very similar to those obtained by physical modeling in our earlier studies using plasticine. Equiaxed ultrafine-grained structure (average grain size = 0.53 μm) was obtained after ECAP at an equivalent shear strain of 6.0. This article is based on a presentation given in the symposium entitled “Materials Behavior: Far from Equilibrium” as part of the Golden Jubilee Celebration of Bhabha Atomic Research Centre, which occurred on December 15–16, 2006 in Mumbai, India.

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Microstructure and Mechanical Properties of High Manganese TRIP Steel

 Abstract： Microstructure evolution and mechanical properties of newly designed 01C-6Mn-05Si-1Al TRIP-aided steels under different annealing conditions and the effects of matrix microstructure before intercritical annealing on the final microstructure were studied by means of X-ray diffraction (XRD), scanning electron microcopy (SEM), dilatometric simulation, optical microstructure (OM) and tensile testing in this work. The experimental results indicate that the TRIP steel with Mn of 6% could form a considerable amount of retained austenite with good TRIP effect after a simple intercritical annealing treatment, and the matrix microstructure before intercritical annealing treatment can greatly affect the final microstructure. The original microstructure of the ferritic matrix steel was eliminated, while annealed martensite was remained from the martensite matrix steel under the same intercritical annealing conditions.     

等通道热挤压变形制备奥氏体不锈钢纳米级组织

 通过采用700 ℃等通道挤压法(ECAP法)对00Cr19Ni10奥氏体不锈钢实施变形,制备出晶粒尺寸在200~300 nm的超细晶组织,由此可使其抗拉强度与屈服强度显著增加。同时探讨了ECAP细化机理,对试验钢在等通道挤压变形中的微观组织演变过程进行了分析,发现其组织演变与滑移、孪晶以及动态再结晶有关。