大应变冷拔钢丝的强化模型

采用扫描电镜观察了不同应变量拉拔变形后SWRH72A钢丝的显微组织,并统计了珠光体片层间距的变化。通过透射电镜分析了变形后铁素体中的位错分布状态,测量了不同应变量拉拔变形后钢丝的力学性能,并基于钢丝微观组织结构建立了钢丝的强化模型。结果表明,随着拉拔应变量的增大,珠光体片层间距逐渐减小,钢丝强度随之升高。综合分析珠光体片层间距和钢丝强度的变化规律得出,应变量较小时,珠光体片层间距较大(>100nm),钢丝加工硬化符合Hall-Patch定律;应变量较大时,珠光体片层间距较小(<100nm),钢丝加工硬化符合奥罗万(Orowan)机制。     

SWRS82B盘条冷拔过程中显微组织和力学性能的变化

SWRS82B盘条通过热轧控冷获得95%以上的索氏体组织,其珠光体片层间距越小,冷拉拔过程中将具备越好的综合力学性能。随着钢丝拉拔应变量不断增大,珠光体片层间距不断减小,抗拉强度和屈服强度不断增大,伸长率不断下降。当珠光体片层间距由202 nm拉丝减小至60 nm以下,钢丝抗拉强度则由1371 MPa增大至2088.6 MPa,伸长率由11%降至7.16%;钢丝截面上的显微硬度值随着应变量的增加而增大,并表现出各向异性变化。     

SWRS82B钢盘条的显微组织对力学性能的影响

采用盐浴等温冷却和风机连续冷却,SWRS82B钢热轧盘条能获得珠光体团尺寸7.58 μm、片层间距201 nm的均匀细小索氏体组织;随着珠光体片层间距的增大,盘条抗拉强度Rm、伸长率A等力学性能指标降低;细小的珠光体片层间距使盘条具有更好的综合力学性能,有利于提高钢丝拉拔成材率和获得高性能钢丝绳.     

钢帘线用1.02%C钢丝的索氏体化处理

对1.02%C钢丝进行铅浴等温转变和水浴连续转变两种索氏体化处理。通过SEM、拉伸试验机、扭转分层仪、亨特疲劳试验机及振动样品磁强计对钢丝和单丝的微观组织和力学性能等方面进行分析。结果发现,由于铅浴钢丝从边部到心部珠光体片层间距均小于水浴钢丝,导致铅浴钢丝抗拉强度和断面收缩率均高于水浴钢丝。水浴钢丝珠光体片层间距波动较大,导致力学性能波动增大。两种钢丝湿拉得到的单丝微观组织均为平行于拉拔方向的纤维组织。铅浴钢丝经应变量ε=3.584湿拉得到单丝的抗拉强度、亨特疲劳极限以及扭转值均高于水浴钢丝。由于水浴钢丝在湿拉过程中渗碳体溶解量高达34.3%,导致单丝出现分层以及亨特疲劳性能下降。     

冷拉拔珠光体钢丝的组织结构和残余应力(英文)

采用扫描电子显微镜和X射线衍射技术,分别研究了珠光体钢在冷拉拔过程中的组织结构和残余应力演化。随着拉拔应变量的增大,珠光体团逐渐转向拉拔方向。影响珠光体钢丝屈服应力和抗拉强度的关键因素是珠光体片层间距,它们之间满足Hall-Petch公式,通过拉伸试验求得其中k值为567.4kN·m-3/2。钢丝残余应力的X射线衍射测量结果表明,随着应变量增加,钢丝的应力增大,这与拉拔过程中的加工硬化有关。     

冷变形珠光体钢丝的微观组织演变及强化效应

采用显微硬度测试、扫描电镜(SEM)、透射电镜(TEM)和三维原子探针(3DAP)等测试手段分析了珠光体钢丝在冷拔过程中显微硬度、组织变化及大应变变形后碳原子的分布和浓度变化。结果表明:随着应变量的增加,组织逐渐转向拉拔方向,片层间距减小,最后在纵截面上形成平行于拉拔方向的层片状组织,横截面上呈现为卷曲状的层片组织;3DAP测试显示,渗碳体在变形过程中发生了部分溶解,溶解的碳原子从渗碳体相移动到铁素体相,碳原子在铁素体中形成过饱和;在拉拔过程中铁素体内部位错密度增加、片层间距减小和渗碳体发生分解释放出碳原子对位错运动产生较大阻力,使珠光体钢丝的硬度随着拉拔应变量的增加而增加。     

0.92%C超细钢丝组织控制及断裂分析

研究了不同等温铅浴淬火后0.92%C钢丝的组织与性能,并对钢丝断裂机理进行了分析。结果表明,提高奥氏体化温度至980 ℃、降低铅浴温度至585 ℃,直径φ 0.84 mm钢丝中珠光体含量高,片层间距细小、均匀,抗拉强度、断面收缩率及硬度均达到最大,且钢丝拥有较强的连续拉拔性能,湿拉过程中的断丝率仅为0.004次/km。     

深度冷拉珠光体钢丝的显微组织与力学性能

采用 SEM、XRD和材料试验机研究了不同拉拔变形量下珠光体钢丝的微观组织演变以及力学性能.实验结果表明,随着拉拔应变量的增大,珠光体团发生转向,片层组织趋于拉拔方向排列,片层间距逐渐减小,渗碳体片发生明显的扭曲或塑性变形.随着应变量的增大,铁素体的{110}α{200}α和{211}α晶面的衍射峰都发生不同程度的宽化,衍射强度降低,并出现峰位的左移.钢丝的强度和屈强比均随拉拔应变量的增大而增大,而塑性则随拉拔应变量的增大而减小.     

钢中珠光体组织层片间距的测量

本文在研究了珠光体层片的取向分布和考虑到层片间距本身的统计分布的基础上,推导了珠光体层片的真实间距和表观间距的关系式,得到一种测定钢中珠光体组织的真实平均层片间距的实用方法。将此法应用于经不同热处理的车轮,测量结果表明机械性能较高的车轮,其珠光体层片间距较小。     

冷拉拔珠光体钢丝中渗碳体变形与溶解研究

采用SEM、TEM和XRD研究了珠光体钢丝冷拉拔过程中的组织演变,重点在于渗碳体的变形和溶解。结果表明,渗碳体表现出了很高的变形能力,随着累积应变量的增大,片条组织逐渐转向拉拔方向;在大应变钢丝组织中渗碳体片条厚度小,部分区域只有0.5nm甚至更薄,且已很难见到渗碳体的滑移或剪切变形。在初始钢丝中铁素体含有过饱和的碳,在拉拔应变量为1.51之后,可能转变为四方结构的马氏体,且只有很少量的渗碳体溶解。在高应变量钢丝样品中,用原子探针场离子显微镜探测碳原子浓度以判定渗碳体是否溶解时,应考虑渗碳体的形变及其形貌。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 k Hz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more {110}116 grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, {110}116 can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of {110}116 grains and therefore enhance the sharpness of Goss texture.     

Laser Cladded TiCN Coatings on the Surface of Titanium

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80?滋m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

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正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis