提高塑料模具寿命研究进展

本文从新型塑料模具钢研制，塑料模具表面强化技术开发两方面综述了国内在提高塑料模具寿命研究方面的进展。国产新型塑料模具钢主要有预硬钢，时效硬化钢，淬火－回火钢，冷挤压成型模具钢，耐蚀钢等类型。     

相同成分DP钢和TRIP钢部分力学性能的比较

对同一种钢板进行不同热处理分别制成具有相同铁素体含量的双相钢（DP钢）和相变诱发塑性变形钢（TRIP钢），并对其部分力学性能进行对比。比较发现，铁素体基体上不同的第二相使得材料力学性能产生巨大差异：马氏体使DP钢具有很高的抗拉强度，残余奥氏体则赋予TRIP钢优良的伸长率；DP钢拥有更加优良的加工硬化能力，TRIP钢则具有较为理想的烘烤硬化能力。试验还表明，考察DP钢和TRIP钢的烘烤硬化能力时，除柯氏气团外，内应力的消除也应该考虑其中。     

模拟海洋大气环境对XCS-lode钢与30CrNi3Mo钢腐蚀行为的影响

采用盐雾腐蚀试验方法，研究了模拟海洋大气环境下XCS-lode钢与30CrNi3Mo钢的腐蚀性能，通过极化曲线及电化学阻抗谱(EIS)试验研究了两种钢在腐蚀行为上的差异。结果表明：XCS-lode钢相比30CrNi3Mo钢具有更高的自腐蚀电位， XCS-lode钢腐蚀产物膜的阻抗明显大于30CrNi3Mo钢，XCS-lode钢的耐海洋大气腐蚀性能优于30CrNi3Mo钢。     

矿井支护钢调质工艺及应用

介绍了采用多匝线圈感应加热对矿井支护钢进行调质处理的工艺及设备的特点，矿工钢通过调质处理，综合性能大幅度提高，调质后的矿工钢比热轧矿工钢的抗弯强度提高2.5倍，从而可以用小截面的矿工钢代替大截面的矿工钢，适当加大棚距，节省钢材。     

新型低锰微铌钢与普通Q355钢焊接性能比较

通过焊接热影响区最高硬度试验、斜Y形坡口焊接裂纹试验、典型对接接头性能评价试验及典型对接接头疲劳性能试验，结合金相显微镜（optical microscope,OM）和扫描电子显微镜（scanning electron microscope,SEM）两种表征手段，深入研究了新型低锰微铌钢（MnNb钢）与普通Q355钢（Q355钢）焊接性能差异及机理。结果表明，在不预热条件下，Q355钢表现出强烈的焊接淬硬倾向，而MnNb钢无淬硬倾向；MnNb钢和Q355钢均具备优良的防止焊接冷裂纹性能。相比于Q355钢接头，Mn Nb钢对接接头抗拉强度稍低，但其热影响区冲击吸收能量明显更优，这主要是由于Q355钢粗晶区中存在细小的晶内组织和侧板条铁素体组织，而MnNb钢粗晶区具有大量针状铁素体与较小的原始奥氏体晶粒。MnNb钢接头的条件疲劳极限强度比Q355钢接头高57 MPa，其扩展区疲劳辉纹间距更小，裂纹扩展速度更慢，MnNb钢对接接头的疲劳性能显著优于Q355钢对接接头。     

120和125钢级钻杆在NACE溶液中腐蚀行为研究

将改进型27CrMo材料热处理成120和125钢级钻杆，采用电化学技术测试、浸泡试验和硫化物应力腐蚀试验，对比分析了两种钢级材料的腐蚀性能。结果表明：120钢级钻杆出现椭圆状腐蚀坑，而125钢级钻杆出现细长的腐蚀坑，腐蚀坑深度约为120钢级钻杆的两倍，且坑底出现腐蚀裂纹。120钢级钻杆通过了NACE TM 0177 A法D溶液抗硫化物应力腐蚀试验，而125钢级钻杆发生断裂，断裂方式为沿晶断裂，故125钢级钻杆抗硫应力腐蚀性能不佳。     

40Cr钢强韧化处理后的力学性能

研究了40Cr钢亚温淬火的强韧化机理，并与40Cr钢常规热处理后的力学性能进行比较。结果表明，亚温淬火可提高40Cr钢的冲击韧度，降低40Cr钢的韧脆转变温度，抑制40Cr钢的回火脆性。     

双相钢在冷拔单体液压支柱缸筒中的应用

介绍了双相钢的特征，分析了其性能优良的原因，比较了１０ＭｎＳｉ双相钢和２７ＳｉＭｎ低合金高强度钢的σ－ε曲线，钢和冷拔管的机械性能及工艺性能等。结果表明，双相钢适合冷拔制造液压支柱缸筒，其综合经济效益较好。     

土壤中侵蚀性离子对X70钢的侵蚀作用研究

采用极化曲线并结合E-pH图分析，研究了土壤中主要侵蚀性离子CO2-3、HCO-3、SO2-4、Cl-对管线钢X70钢的侵蚀作用。结果表明：在酸性介质中，SO2-4、Cl-2种离子对X70钢的侵蚀能力无明显差别；X70钢在含有SO2-4、Cl-离子的介质中发生活性溶解，由于含有多种钝性元素以及材料的组织结构较均匀，X70钢在此介质中的耐蚀性优于A3钢。但在含有CO2-3、HCO-3的碱性体系中，X70钢的耐蚀性随pH值变化。在含有HCO-3的弱碱体系（pH=8）中，X70钢具有一定的钝化能力，但A3钢的耐蚀性优于X70钢，在含有CO2-3的中等碱体系（pH=10）中，X70钢的耐蚀性优于A3钢，在含有CO2-3的强碱体系中,A3钢的耐蚀性优于X70钢。      

新型氮化钢25Cr5MoA的试制

为满足柴油机柱塞套用材料的要求，开发质量优于38CrMoAlA钢和GCr15钢的材料，研制了一种新型氮化钢25Cr5MoA。首先分析确定了材料的化学成分，然后电炉冶炼得材。试验测定了该钢的CCT曲线，探讨了淬火和回火加热温度对该钢力学性能的影响。结果表明，该钢具有良好的淬透性和较好的综合力学性能。     

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。