Transval型无缝管三辊轧机的液压控制系统

大多数Assel型轧管机轧辊孔型的调整机构是机械式的。在管坯轧制始终轧辊孔型喉口保持不变。这种机构对于厚壁管的生产来说是令人满意的,但是对于生产薄壁管来说,就会引起一系列问题。当轧制薄壁管(其直径与壁厚之比D/t大于10)时出孔型的     

铝/钢复合管轧制开裂的原因分析

对影响铝/钢复合管冷轧开裂的因素进行了研究,从轧制的加工率、送进量及润滑剂三方面对复合管开裂的影响进行了分析。在润滑剂确定的情况下,导致轧制开裂的主要因素有两个:管材的相对壁厚越薄,越易开裂;管材的外径小于轧辊直径,管材容易开裂。选择合适的润滑剂和送进量,可以避免轧制开裂。     

周期轧管机轧制套管工艺参数

<正> 为将周期轧管机组生产套管的轧制工艺修订更符合ГОСТ632-80(A)的要求,苏联管材科研所与几家钢管厂共同就周期轧管机和定径机的变形参数对钢管几何尺寸精度和1m钢管重量的影响进行了研究。在下列几家钢管厂的轧管机上轧制了不同尺寸的Д和Е强度级薄壁管:在塔干罗格     

A THEORETICAL ANALYSIS ON LARGE SIZED TUBE MILLING BY PLANETARY SKEW ROLLING

行星斜轧轧管工艺是用于轧制大直径与特大直径无缝管材的。本文阐述了行星斜轧轧管过程的运动学、力学、金属塑性变形、真实变形、轧制力及轧制力矩的计算等基本理论问题,为进行行星斜轧轧管工艺与设备的设计提供了依据。     

行星斜轧轧管工艺的理论分析

行星斜轧轧管工艺是用于轧制大直径与特大直径无缝管材的。本文阐述了行星斜轧轧管过程的运动学、力学、金属塑性变形、真实变形、轧制力及轧制力矩的计算等基本理论问题,为进行行星斜轧轧管工艺与设备的设计提供了依据。     

钢管斜轧延伸的金属变形研究及孔型设计(上)

简要分析了斜轧延伸轧管技术的发展状况。通过对AccuRoll轧管机变形区中金属变形的理论分析和试验研究,探讨了轧制工艺特征和工具对轧制变形的影响。在将计算机技术应用于变形区模拟分析和钢管主变形分析后,提出了斜轧延伸孔型设计的基本原则。试验研究表明,通过AccuRoll轧管机的孔型设计,可实现减径、等径和扩径3种轧制形式。通过优化孔型设计,用AccuRoll轧管机轧制薄壁管,其D/S值已达到41。该工艺技术的发展将进一步提高轧制薄壁管的稳定性和轧制速度。     

钢管斜轧延伸的金属变形研究及孔型设计(下)

简要分析了斜轧延伸轧管技术的发展。通过对AccuRoll轧管机变形区中金属变形的理论分析和试验研究,探讨了轧制工艺特征和工具对轧制变形的影响。并将计算机技术应用于变形区模拟分析和钢管主变形分析,提出了斜轧延伸孔型设计的基本原则。试验研究表明,通过AccuRoll轧管机的孔型设计,可实现减径、等径和扩径3种轧制形式。通过优化孔型设计,用AccuRoll轧管机轧制薄壁管,其D/S值已达到41。该工艺技术的发展将进一步提高轧制薄壁管的稳定性和轧制速度。     

改善φ140机组生产大直径薄壁管壁厚不均的一项有效措施

本文介绍了φ140自动轧管机组生产大直径薄壁管时,壁厚不均沿横断面的分布特点。生产大直径薄壁管,适当增加轧管机第一道减壁量,可以改善螺旋形分布的壁厚不均,降低壁厚超出公差的待修品率。     

减小φ140mm自动轧管机组轧管的纵向壁厚不均

介绍了消除φ140mm自动轧管机组轧制薄壁管的纵向壁厚不均的经验。试验证明,在自动轧管机轧制之前采用毛管温度补偿方法可使纵向壁厚不均从0.3下降到0.06mm。     

采用两种定径工艺提高140—325周期轧管机组的生产效率

<正> 组成现代周期轧管机组的12架减-定径机,在周期轧管机后轧制薄壁管的直径压下量可以达到14%。此时,由于减-定径机同时工作的机架数量不同,因此,钢管的直径压下量可达很宽的范围。值得注意的是,在所轧制的品种中钢管相邻规格的彼此直径差为26～28毫米,因而,供给减-定径机的钢管直径范围是很宽的。在这个机组上,利用全部12个机架、最大压下量30～35毫米,可轧出最小尺寸的成品钢管(工艺Ⅰ),而同样直径的钢管,利用后部的4～5机架,直径压下4～10毫米,则可轧出大尺寸的成品钢管     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

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。     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

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.     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.