预置表面织构对硬态切削加工的影响分析

利用电火花穿孔技术预置表面织构,有效抑制硬态切削过程中较大切削力的产生,避免刀具磨损加剧,提高刀具使用寿命。使用CBN刀具硬态切削GCr15淬硬钢,设计关于切削深度、切削速度、进给量三因素无织构正交切削仿真模拟及试验,利用极差、方差及信噪比值法对仿真及试验数据进行分析,确定最佳切削参数组合,以及各参数对硬态切削过程中产生的切削力的影响程度。使用最佳切削参数组合,硬态切削预置表面织构的GCr15淬硬钢,观测刀具磨损情况,测量切削力,并与无织构等同切削条件下的结果进行对比分析,验证预置表面织构能够有效降低刀具磨损,提高刀具使用寿命。     

TiN涂层刀具切削淬硬H13钢切削性能试验研究

为研究TiN涂层刀具切削淬硬H13钢的切削性能,进行了TiN涂层刀具车削加工淬硬H13钢试验。分析了切削用量与切削力、切削温度的关系及涂层刀具磨损机制。研究得出切削速度、切削深度、进给量都对主切削力Fz和切深抗力Fx影响较大,对切削进给抗力Fy影响相对较小;切削速度对切削温度的影响最大;对刀具磨损观察发现刀具的前刀面有明显的月牙洼磨损,刀尖部位出现了微崩刃现象,后刀面出现磨粒磨损。研究结果为生产加工中优化切削用量及提高刀具寿命提供了技术支持和试验依据。     

淬硬钢超声振动车削试验研究

超声振动切削淬硬钢,刀具磨损、表面粗糙度、切削力、切削温度都较小,是淬硬钢切削加工的有效途径。     

基于矩阵分析法的CBN刀具干式硬车参数优化研究

由于具有良好的环保性、经济性和加工柔性,硬态干式切削技术近年来得到了快速发展,并在淬硬钢的精加工中获得了应用。基于切削试验和Deform-3D有限元软件仿真,对CBN刀具干式硬车淬硬钢Cr12MoV加工表面粗糙度、切削力及切削温度等指标进行了研究。采用矩阵分析法,分析并计算了切削用量三要素对表面粗糙度、切削力和切削温度的综合影响,得到了最优切削参数组合。结果表明:该方法对分析试验工况条件,寻找最优试验方案具有简洁、高效的优点;对研究指标综合影响的显著程度由高到低依次为切削深度、切削速度和进给量。     

PCBN刀具高速切削淬硬钢材料的研究

以PCBN复合片为刀具材料进行相关力学性能分析,并将其制成SNGN120408型刀具后在刀具机床上进行淬硬钢切削试验。分析结果表明:PCBN复合片的结合剂主要为TiN和TiB₂,其内部结构均匀,且有良好的致密性。切削试验表明:在干式切削淬硬钢的试验中,切削进给量以及切削速度对PCBN刀具的磨损有较为明显的影响。相比于切削速度,进给量对淬硬钢工件表面的粗糙度影响更大。PCBN刀具高速干式切削淬硬钢的磨损为黏结磨损、局部剥落和扩散磨损等多重磨损共同作用的结果。      

PCBN刀具干式车削淬硬钢的试验研究

通过切削试验,得出了聚晶立方氮化硼(PCBN)刀具干式车削渗碳淬硬钢20CrMnTi时的刀具耐用度及其与切削速度的关系曲线,建立了刀具耐用度与切削速度的经验公式,并研究了加工的表面粗糙度.     

基于高速切削的淬硬钢加工技术研究

淬硬钢高速铣削加工具有传统加工无可比拟的优势,是淬硬钢加工的发展方向.本文从切削刀柄和刀具、加工工艺、数控编程等方面阐述了淬硬模具钢高速加工的技术特点.     

陶瓷刀具断续车削淬硬钢失效演变机理研究

选用Al2O3/(W,Ti)C陶瓷刀具断续车削淬硬钢,进行正交切削试验,分析切削用最对刀具寿命的影响.建立了断续切削条件下不同失效演变阶段的刀具寿命公式,并通过以切削速度为单一变量的单因素试验,对其进行验证.针对不同失效演变阶段的刀具寿命公式进行分析讨论.结果表明:切削用量三要素对刀具寿命影响程度的大小顺序为:vc>αpf;在刀具失效演变的不同阶段,机械载荷、热载荷对刀具破坏的影响程度不同.     

表面织构对GCr15淬硬轴承钢切削过程影响分析

针对GCr15淬硬轴承钢切削过程中由于切削力大、切削温度高而导致的刀具磨损加剧问题,在工件表面预置织构,通过有限元仿真结合正交试验对切削过程进行模拟,并通过信噪比分析方法进行优化分析,利用极差分析、方差分析确定最优切削参数组合以及切削参数对于切削力以及温度的影响程度。切削仿真结果表明:切削速度120 m/min、进给量0.05 mm/r、切削深度0.1 mm为最优切削参数组合。在最优切削参数条件下,通过对表面织构GCr15轴承钢进行切削仿真模拟,得到切削力以及切削温度的仿真结果。将表面织构和无表面织构的切削仿真模拟结果进行对比,结果表明表面织构切削仿真的切削力及切削温度都得到有效降低,有利于减少刀具磨损,提高刀具寿命。     

淬硬钢的导电加热切削实验研究

采用导电加热切削方法对淬硬GCr15轴承钢进行切削试验,分析这种加工方法的可行性,研究了切削量对表面粗糙度的影响规律。研究结果表明：导电加热切削能有效切削淬硬钢,显著降低表面粗糙度值;在较优的切削用量下,表面粗糙度可达到Ra0.25μm。     

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。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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.     

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.     

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.