介绍几种新型模具钢

1.65Nb(65Cr4W3MoVNb):是一种性能优良的冷作模具钢,由华中工学院和大冶钢厂研制,主要用于冷冲、冷挤、冷镦的凸、凹模。2.8Cr7Mo3V2Si:这是由上海材料研究所研制的一种强韧性冷模具钢,强度高、韧性好、耐腐蚀。3.012Al(50Cr4Mo3SiMnVAl):由贵阳钢厂研制的冷热兼用、性能较好的新模具钢。4.CG(2C6Gr4Mo3Ni2WV):由上海钢铁研究所和贵阳钢厂等单位研制的冷热兼用、性能较好的模具钢。5.GR(4Cr3Mo3W4VTiNb):由上海材料研究所和大冶钢厂研制,高温屈服强度     

新型耐磨冷作模具钢GM钢的应用

<正> 华中理工大学新近研制的新型耐磨冷作模具钢 9Cr 6W 3Mo 2.5V 2.5钢,简称GM钢。我厂采用该GM钢用于制作级进模具和高速冲模,这样扩大了冷作模具钢的钢种选用范围,且提高了冲制零件的质量和模具的使用寿命。 一、GM钢的成份及组织特点     

一种新型冷作模具钢DC53钢试验研究

本文介绍了一种新型冷作模具钢DC53钢的物理性能和热处理工艺,探索了DC53钢作为模具镶块材料的使用寿命。与冷作模具钢7Cr Si Mn Mo V进行了性能比较试验,结果表明,相同工况下,DC53钢寿命是7Cr Si Mn Mo V钢的5~6倍,使用DC53钢代替7Cr Si Mn Mo V钢在铁路货车用冷冲压模具中是可行的。     

高强韧性冷作模具钢—Cr7Mo3V2Si

本文介绍一种新型高强韧性冷作模具钢——Cr7Mo3V2Si(代号LD),它具有强度高、韧性好、耐磨损、工艺性能优良、热处理温度范围宽、变形小等特点。抗弯强度比Cr12MoV钢高出将近一倍,比W6Mo5Cr4V2钼高速钢高出50～80kgf/mm~2,挠度和冲击韧性比Cr12MoV和W6Mo5Cr4V高出二～三倍。机械性能达到了国外同类型钢种(美国专利)的水平。经冷镦、冷挤、冷冲等几十种模具在生产上应用及试用都取得了较长的使用寿命。尤其是M12六角螺栓冷镦模平均寿命达52.4万件,达到了美国资料报导的同类模具50万件寿命的先进水平。     

用GM钢提高硅钢片冲模寿命

本文利用新型高耐磨、高强韧性冷作模具钢9Cr6W3Mo272(简称 GM钢),显著提高了电机转子复式冲模的使用寿命。     

几种具有优良性能的模具钢

介绍了几种具有优良性能的模具钢 :7Cr7Mo2V2Si(LD) ,高强韧冷作模具钢 ,强韧性好 ,耐磨损 ;1 0Ni3MnCuA1 (PMS) ,时效硬化镜面塑料模具钢 ,镜面加工性能优异 ,冷热加工性能和电加工性能良好 ,热处理变形小 ;4Cr5Mo2MnVSi(Y1 0 )。,专用于铝合金压铸模具 ,抗冷热疲劳性能好 ,热处理变形小 ,抗铝溶损性能好 ;4Cr3Mo2MnVNbB(Y4) ,热作模具钢 ,强韧性好 ,热稳定性好 ,抗冷热疲劳性能好 ,4Cr3Mo3W 4VNb(GR)热作模具钢 ,高温强度高 ,热稳定性好 ,抗冷热疲劳性能好。     

高强韧性冷模具钢65Nb的改锻

<正> 65Cr4 W3Mo2VNb钢(简称65Nb)是一种新型高强韧性冷模具钢。由于具有高的强韧性,能满足模具的高强度、硬度和耐磨性的要求。65Nb钢经过合理锻造制成的冷冲、冷镦、冷挤压模具,比常用模具钢的模具使用寿命长,经济效果明显,已不断得到推广。     

新型高强韧冷作模具钢JK2的应用

将新型冷作模具钢JK2(7Cr4Mo4SiV1和7Cr5Mo3SiV)分别应用于冷挤压模具、冷冲模具和粉压模具,试验研究了与之相应的热处理工艺和表面强化处理工艺。经工厂使用表明,模具使用寿命比原用材料分别提高了2～10倍。     

4Cr2Mo2W2V钢中碳化物的演变对热稳定性的影响

利用高分辨透射电镜观察、能谱分析等实验方法,结合硬度试验、热稳定实验不同温度下的实验数据,对热作模具钢4Cr2Mo2W2V中的组织成分、碳化物的形态、大小及其演变规律和对材料高温性能的影响进行了研究。结果表明：热稳保温过程中碳化物的演变与马氏体回复过程是耦合出现的,4Cr2Mo2W2V钢在工作温度620～700℃下的热稳定性能优于传统热作模具钢3Cr2W8V,4Cr2Mo2W2V钢在650℃工作温度下的热稳定性与传统热作模具钢3Cr2W8V在620℃条件下相当。基体中的较多的Mn和相对稳定细小的Mo、V系碳化物保证了4Cr2Mo2W2V钢高温时效过程中能保持一定的硬度。     

高速钢亚温淬火与氮碳共渗工艺对性能的影响

研究了亚温淬火与表面强化处理对W18Cr4V和W6Mo5Cr4V2高速钢冷作模具性能的影响.结果表明,经亚温淬火处理后的W18Cr4V (1160～1180 ℃)、W6Mo5Cr4V2 (1130～1150 ℃)两类模具的使用寿命均比以往有明显提高,平均寿命由过去冷镦或冷挤压(常规淬火、回火)3000～3500件提高至6000～7000件;高速钢冷镦模及冷挤压模再经560 ℃氮碳共渗后200 ℃保温2 h去氢处理后,表面硬度达890～940 HV,平均使用寿命达到9500件.     

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。