挤压轮用热作模具钢的研究

设计了一组新型含N热作模具钢,通过显微组织、力学性能、热疲劳试验,优选出试验钢成分,之后对最佳成分钢进行热处理工艺优化。结果表明;最佳V、Cr、N成分分别为1.0%、3.75%、0.01%(质量分数)。最佳成分钢优化热处理工艺为1080℃淬火+550℃一次回火+530℃第二次回火。     

热处理工艺对TBM刀圈材料耐磨性的影响

采用金相、TEM等方法研究了热处理工艺对自行研制的全断面掘进机用盘形滚刀材料的耐磨性的影响。结果表明：自行研制盘形滚刀材料最佳热处理工艺为1060℃淬火＋530℃－560℃二次回火，此条件下获得的咽火马氏体组织具有很好的耐磨性能。     

新型热作模具钢CH75的组织与性能

研究了新型热作模具钢的热处理工艺，组织与性能的关系，并与常用的热作模具钢进行比较，结果表明ＣＨ７５钢具有较３Ｃｒ２Ｗ８Ｖ和Ｈ１３钢优异的回火稳定性和高温性能，适宜做工作温度为７００℃左右的热作模具。     

Cr12MoV钢大型矫直辊的热处理

对Crl2MoV大型矫直辊进行了热处理试制生产。矫直辊预处理工艺为锻后余热淬火及回火，最终热处理采用1030℃整体保护加热淬火和230℃两次回火，辊身表面硬度和变形量均达到技术要求。     

新型热作模具钢H13的热加工工艺研究

Ｈ１３钢（４Ｃｒ５ＭｏＶ１Ｓｉ）是新型的热作模具钢，可以广泛用于要求高韧性和冷热疲劳抗力，工作温度≤７００℃的热作模具，理论和实践证明，只要正确地实施锻造和热处理常规工艺，Ｈ１３钢的热加工质量具有可靠保证；推广和应用先进的热加工工艺技术，能提高Ｈ１３钢的使用性能和寿命。     

热作模具钢CH75的工艺性能研究

研究了热作模具钢ＣＨ７５的工艺性能，实验结果表明：ＣＨ７５钢热塑性较好，具有较小的脱碳敏感性，较高的热稳定性和良好的抗氧化性能；热处理工艺简便易行。     

含氮不锈轴承钢的热处理工艺研究

本文通过不同的热处理工艺研究了含氮不锈轴承钢40Cr15Mo2VN的淬火温度、冷处理工艺、回火温度与硬度和残余奥氏体之间的关系,得出该钢种的最佳热处理工艺为1060℃/1 h淬火、两次-196℃/2 h冷处理和160℃/2 h回火。     

金属材料断裂韧性数据手册

16.9Ni-4Co-0.3C钢(厚76.2mm板材)(1)化学成分(％),见表16.1。(2)热处理工艺热处理采用844℃×2小时+538℃×2小时两次回火。(3)断裂韧性,见表16.2。     

热处理工艺对高速钢轧辊组织和硬度的影响

研究了热处理工艺对高速钢轧辊组织和硬度的影响,获得大型复合铸造高速钢轧辊优化的热处理工艺为:1 050℃淬火(加热时表面涂抗氧化涂料)、500℃两次回火、250℃长时间消除残余应力回火.经此上艺热处理的高速钢轧辊,硬度高、耐磨性好,残余应力得到较充分的释放.     

Cr26型高铬铸铁组织性能及其热处理工艺

研究了Cr26高铬铸铁化学成分的控制范围和热处理工艺对其硬度和冲击性能的影响,分析了该成分高铬铸铁经过不同热处理后的组织.结果表明,采用文中所述生产工艺和1 040℃±10℃×6h特殊淬火液淬火+275℃×6h或440℃×6 h回火的热处理工艺,高铬铸铁硬度达60 HRC以上,冲击韧度达10 J/cm2,其耐磨性是高铬铸铁Cr15的1.32倍,高锰钢ZGMn13的1.95倍.     

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.     

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。