GH901合金锻件晶粒级别与均匀性对探伤杂波及底波损失的影响

针对多批次GH901高温合金锻件探伤底波损失与杂波超标不合格的质量问题,开展了多次GH901合金锻造工艺试验,根据锻件不同位置的超声波探伤结果与对应位置晶粒组织进行分析,得出晶粒组织对GH901合金锻件超声波探伤底波损失与杂波的影响。研究结果表明,GH901合金锻件超声波探伤底波损失与晶粒组织的粗细及均匀性存在对应关系,晶粒越细则超声波探伤底波反射回波越高,杂波低;晶粒越粗则超声波探伤底波反射回波越低,杂波高,当合金锻件晶粒达到2级或更粗时,锻件探伤杂波超标;当GH901合金锻件各区域组织差异较大时,锻件探伤底波损失不合格。     

等温锻造GH710合金组织与性能

为解决GH710合金普通锻造时变形困难、组织性能不均匀的技术问题,开展了GH710合金等温锻造工艺研究.对等温锻造GH710合金变形性能、微观组织和力学性能进行了分析,结果表明,等温锻造工艺可有效改善GH710合金变形性能、细化晶粒组织、提高合金力学性能.GH710合金经1100 ℃变形量为50%和70%的等温锻造后,均具有良好的力学性能,特别是其持久性能得到大幅度提高,815 ℃缺口持久性能达到100 h之上,980 ℃光滑持久性能达到80 h之上.采用等温锻造工艺研制出了Φ240 mm的GH710合金涡轮盘模锻件,锻件外观完整、晶粒组织细小均匀,力学性能稳定,等温锻造工艺是制备GH710合金细晶涡轮盘的理想工艺.     

锻造温度和变形量对GH4698合金锻件高温蠕变性能的影响

对GH4698合金在不同锻造温度和变形量下进行了锻造工艺试验,研究了锻件的显微组织和高温蠕变性能并进行了超声波检测,分析了锻造温度和变形量对GH4698合金锻件的组织和蠕变性能的影响规律。结果表明,组织均匀、晶粒相对较大的锻件高温蠕变性能较好,提高锻造温度和控制极限变形量能得到均匀粗大的组织。但温度过高会引起锻件晶粒过大,超声波检测难以达到要求。     

锻造工艺对GH901高温合金涡轮轴锻件磨损性能的影响

采用不同的始锻温度、终锻温度和锻压速度对GH901高温合金涡轮轴毛坯进行了锻造,并分别进行了25℃室温和600℃高温环境下的耐磨损性能测试与分析。结果表明:在试验条件下,随始锻温度从1060℃升高至1140℃,终锻温度从860℃升高至940℃,或锻压速度从6 mm/s增加至12 mm/s,锻件的室温和高温磨损体积均先减小后增大,耐磨损性能先提高后下降。高温合金涡轮轴锻件始锻温度优选为1120℃,终锻温度优选为920℃,锻压速度为10 mm/s。     

GH3044合金模锻件的组织及力学性能

针对GH3044合金采用自由锻+模锻的工艺进行了精密成形研究,并对GH3044模锻件的组织及性能进行了探讨.试验表明GH3044合金模锻件在终锻变形量为10%以上的情况下能够得到合格的组织,并具有良好的性能.     

718Plus高压涡轮机匣超声波探伤缺陷分析

Leap发动机高压涡轮机匣用718Plus合金棒料,经锻造碾环、热处理、机加等工序加工为环形锻件,在超声波探伤检验后,发现内部存在几处异常显示不合格.通过对锻件临近缺陷处的金相组织检验、力学性能测试,并以0.1 mm逐层打磨抛光直至显示缺陷,对缺陷处进行了光学显微观察及EDS成分分析.结果表明,锻件的锻造、热处理过程正...     

F22阀体锻件超声探伤不合格原因的分析

采用5.5t锭型锻造的F22钢锭阀体锻件超声波探伤合格率较低。本文通过无损检验、金相分析、扫描电镜分析、能谱分析等检测手段对超声波探伤不合格试样进行了研究。结果表明:引起阀体锻件超声波探伤不合格的原因是锻件内部中心区域珠光体带中存在微裂纹。微裂纹产生的原因:一方面是钢锭中心锰、钼合金元素偏析引起的组织应力及锻件锻后冷速较快引起的热应力;另一方面是锯切后的钢锭心部存在的裂纹在加热过程中氧化导致锻件一端心部未锻合。     

GH4169合金细长轴锻件局部锻造成形工艺研究

研究了GH4169合金细长轴类锻件局部锻造成形工艺,分析了锻件不同部位的组织演变规律。结果表明,为了避免加热过程晶粒的快速长大,提高不同变形区域内组织的均匀性,合金锻造加热温度应为970℃,整体加热方式能够避免局部加热时魏氏组织的形成。通过分析细长轴类锻件成形工艺特点及锻造难点,并充分利用合金的热加工工艺特征,采用卧锻机局部镦锻成形工艺成功制备出长度超过850 mm的GH4169合金细长轴类锻件,且锻件晶粒尺寸与δ相分布整体上呈现较为均匀的特征。     

GH4169合金支撑锥壁锻件的高温性能分析研究

针对GH4169合金支撑锥壁锻件持久性能不合的现象,通过理化性能检测、工艺参数研究及数值模拟分析,得到了锻件性能不满足标准要求的原因.结果表明,直径350 mm棒料锻造的锻件性能差异大,稳定性更差;锻件截面尺寸变化大,导致终锻件变形不均匀,试样环持久性能不满足标准,需要增加预锻工序.     

GH4720Li盘前封严环成形工艺研究

通过数值模拟和生产检测,确定GH4720Li合金盘前封严环的锻件形状并优化成形工艺参数,制定了成形技术方案.结果 表明,GH4720Li合金盘前封严环锻件的成形方案可行,锻件组织和性能满足要求.     

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。