GH864烟气轮机涡轮盘锻造工艺

GH864材料是一种特殊的镍基高温合金,锻造成形时塑性低、变形抗力大、锻造温度范围窄、导热性差,且锻件的晶粒尺寸不能通过热处理细化,所以要满足锻件的内在质量要求,必须制定合理的工艺路线.从材料的化学成分、锻造工艺、400 MN大型航空模锻液压机和生产流程等方面介绍了GH864合金烟气轮机涡轮盘的生产过程.试验表明,固溶、时效处理后的烟气轮机涡轮盘锻件,力学性能和晶粒度完全达到使用要求.小批量生产后,效果良好,这为烟气轮机发展打下了坚实的基础.     

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。     

铸锻GH710合金组织与性能

对铸锻GH710合金组织和性能进行了研究。结果表明：锻造变形可以消除GH710合金棒材中枝晶组织．细化合金晶粒，提高合金高温持久性能。但具有严重枝晶组织的GH710合金棒材．在锻造变形及热处理后，合金中仍存在残余γ＋γ’共晶组织，它的存在影响合金高温持久性能的发挥。     

以铸代锻——电渣熔铸涡轮盘

某机组涡轮盘尺寸较大,采用 GH36合金要在大型锻压设备上锻造毛坯。大钢锭内部偏析引起锻件的带状组织及点偏析对涡轮盘质量是个问题。而且由于锻压设备条件限制,变形不均匀,锻件的低倍组织和性能均匀性也不好。为了满足该机组涡轮盘的性能要求,选用 GH     

燃气轮机用GH4698合金涡轮盘锻造工艺

燃气轮机涡轮盘材料GH4698是一种特殊的镍基高温合金,其合金化程度较高,锻造时具有较高的变形抗力和较窄的变形温度范围,所以要满足锻件的内在质量要求,必须制定合理的工艺路线。本文从材料的化学成分、锻造工艺、数值模拟和试制生产等方面介绍了涡轮盘的生产过程。经验证通过热处理固溶、时效后的涡轮盘锻件,显微组织、力学性能完全达到使用要求,并且已批量生产。     

直径2000mm超大型高温合金涡轮盘的制造工艺研究

通过大型高温合金钢锭电渣重熔工艺的研究,成功试制出了国内最大高温合金钢锭-GH2674合金φ900mm的钢锭;开发了新的涡轮盘分区变形的锻造工艺,利用4000t快锻机成功试制出了φ1840～φ2118mm的超大型高温合金涡轮盘.采用分区锻造新工艺生产的超大型GH2674合金涡轮盘,组织与性能全部满足技术标准要求,其晶粒组织比传统模锻的大型涡轮盘晶粒组织更加细小,而且不同部位的晶粒组织比较均匀.     

高温合金涡轮盘锻造工艺

航空航天发动机涡轮盘材料GH4133B是一种特殊的镍基高温合金新材料,该材料锻造成形时塑性低、变形抗力特别大、可锻温度范围窄、导热性差,且锻件的晶粒尺寸不能通过热处理细化,所以要满足锻件的内在质量要求,必须制定合理的工艺路线.本文从材料的化学成分、锻造工艺、模具设计和生产试制等方面介绍了涡轮盘的生产过程.其中,为了满足对锻造加热火次和每火次的锻造变形量的控制,提出了锻坯准备、表面清理、表面涂料、加热、刻标记和检验的新工艺路线.经验证通过热处理固溶、时效后的涡轮盘锻件,其力学性能完全达到使用要求,并且已批量生产,效果良好.     

Al-Zn-Mg-Cu高强铝合金等温多向自由锻组织性能研究

针对高强铝合金在多向自由锻造过程中存在热锻开裂严重及组织不均匀等问题,采用不同锻造工艺对新型Al-ZnMg-Cu高强铝合金进行等温多向锻造实验研究。并对经固溶时效热处理后的厚板锻件试样进行了组织观察与力学性能测试。分析对比了采用不同的变形温度、变形方式和锻比等工艺参数对该合金厚板锻件组织和性能的影响。结果表明:在总锻比达到11~12的条件下,采用420℃高温大变形动态再结晶和380℃低温大变形静态再结晶的成形工序均可细化锻件晶粒组织,在保持锻件较高强度性能的基础上,可以改善其塑韧性,并且可以适当减少制坯工序、缩短工艺流程和提高生产效率。     

GH4169合金小余量小尺寸静子叶片锻造工艺及显微组织控制

针对GH4169合金叶片锻件粗晶、混晶等晶粒组织不合格问题,以某压气机小余量小尺寸静子叶片锻件为研究对象,首先分析锻件结构,确定锻造工艺路线,然后通过选取2种规格坯料、5个变形量、4个锻造温度来组成12组试验,探究变形量、锻造温度对组织的影响以及演化规律,同时对选取的保温时间、锻造火次的稳定性进行分析,得到合理锻造工艺参数。研究表明,变形量在35%~45%内可获得均匀的组织,但对晶粒度大小无明显影响;温度是影响晶粒度的主要因素,大于1000℃时叶身晶粒粗化现象明显,在990~1000℃之间叶身可获得细腻、均匀的组织;预锻时组织已成形稳定,终锻无明显变化,在选取的保温时间内组织稳定;在变形量40%及锻造温度990℃下获得的叶片锻件具有优良的综合力学性能及细晶组织,均高于标准要求。     

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。     

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.     

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.     

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.     

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.