40CrNi2MoA钢制烟气轮机主轴的热处理

介绍了40CrNi2MoA钢制大锻件主轴的调质工艺，通过对截面不同位置处力学性能的测试和金相组织的观察，分析了热处理工艺对主轴组织与性能的影响。     

13MnNiMoR钢热成型封头冲击值不合格原因分析及处理方法

13MnNiMoR封头钢板经过热压成型后回火处理,取验证试板做力学性能测试冲击值不合格,对冲击试样进行金相及断口分析表明封头热成型后产生魏氏组织是导致冲击值偏低的主要原因。通过采取重新正火加回火,严格控制正火冷却速度的方式恢复封头的力学性能,满足了使用要求。     

高旁喷管F91材质异常分析及处理

某公司百万千瓦机组高旁喷管采用F91材质锻件,检测发现母材硬度偏低。通过对管道取样进行化学成分分析、微观组织观察、硬度检验、短时常温和高温拉伸试验,发现低硬度区域的金相组织异常,短时力学性能不佳。经分析为制造过程中热处理工艺不当造成,经正火加回火工艺处理后力学性能满足标准要求。通过对比F91/P91里氏及布氏硬度结果,当里氏硬度异常时,应采用布氏硬度计进行校核或者修正。     

焊后热处理对SA508-Ⅲ钢焊接接头力学性能的影响

对核容器采用国产SA508－Ⅲ钢锻件埋弧自动焊接头进行不同规范参数热处理，对接头的拉伸、冲击和硬度等力学性能进行了试验。根据试验结果，分析和讨论了焊后热处理对接头力学性能的影响，对SA508－Ⅲ钢提出了最佳焊后热处理保温温度和时间范围。     

改型CrMo钢螺栓材料热处理工艺研究

从力学性能、金相组织等方面对改型CrMo钢螺栓材料进行热处理工艺试验研究,确定了最佳的热处理工艺规范。通过对冲击断口和透射电镜显微组织分析,掌握了改型CrMo钢的强化和断裂机理,为在生产中使用该钢积累了充足的数据资料,填补了该钢国产化的数据空白,为该材料的进一步开发提供了可靠的理论依据。     

22Cr12NiWMoV锻件晶粒细化及机理研究

为解决22Cr12NiWMoV锻件性能热处理后粗晶问题,采用不同温度热处理相结合方式,观察了金相组织变化特征,并对晶粒细化机理进行阐述。试验结果表明:将22Cr12NiWMoV锻件在非平衡组织状态下,先进行850℃×3h炉冷,再进行1040℃×0.5h油冷、690℃×3h空冷后,晶粒度等级可由2级细化到5级。     

20#锻件冲击值偏低原因综合分析及改进建议

用20#圆钢制做锻件是生产中非常常见的热加工方式,而且,锻件的热加工工艺也不复杂。但是,如果一味的追求生产效率、追求节能降耗,不注意按生产工艺生产,会导致批量的不合格产品出现。本文针对20#圆钢所产生的冲击值偏低而进行了综合分析和研究,并提出了改进建议。     

18CrNi8针阀体内固外气渗碳和高压气淬

本文对18CrNi8针阀体热处理工艺进行了分析和研究。实验证明:通过内固外气渗碳和高压气淬这一新工艺的实施,能有效控制热处理变形,获得最佳的金相组织和力学性能。     

18CrNi8针阀体内固外气渗碳和高压气淬

本文对１８ＣｒＮｉ８针阀体热处理工艺进行了分析和研究。实验证明：通过内固外气渗碳和高压气淬这一新工艺的实施，能有效控制热处理变形，获得最佳的金相组织和力学性能。     

GX12CrMoWVNbN10-1-1钢的热处理工艺试验

通过对GX12CrMowVNbN10-1-1铸钢试料的热处理工艺试验,测定在不同热处理工艺参数下材料的力学性能,进行金相组织分析,确定合理的热处理工艺参数,并通过产品的热处理生产验证.推荐的热处理工艺较好地满足了该材料的各项性能要求.     

高性能9%~12%Cr转子钢发展现状及锻件国产化概况

概括了火电机组汽轮机转子用铁素体耐热钢的发展现状,以及国内外生产与应用情况。介绍了首支COST-FB2国产化锻件的生产试制情况,并将国产锻件性能与国外报道的数据以及进口转子性能进行对比,结果表明,国产锻件能够达到国外水平,但距少数企业的高水平锻件仍存在差距。以国内现有的技术现状为基础,讨论了现阶段高性能转子锻件国产化存在的部分问题,未来需要在电渣冶炼与组织均匀化等多个方面进行技术攻关。     

不同热处理工艺对R26高温合金螺栓组织和性能的影响

针对R26高温合金螺栓在服役过程中所出现的带状组织等缺陷,设计了3种不同的热处理工艺流程来对螺栓组织进行改善,找出最佳热处理工艺.结果表明,经过中间处理+时效处理的试样,内部带状组织消失的同时析出了大量细小弥散的第二相,试样的硬度回落到标准区间,其塑韧性也得到了明显改善,因此为最佳热处理工艺.     

12V190大功率柴油机模锻连杆断裂失效分析

本文通过对190柴油机模锻连杆上的裂纹检验分析，找到了造成该批连杆开裂的主要原因，是由于原材料中存在严重的成分偏析所致。同时指出了连杆在锻造和热处理过程中存在问题。通过这一失效事件，我们也指出了这种原材料缺陷目前在我国国家标准GB3077《合金钢结构钢》中还没有做出限制规定。希望有关单位，今后在制定原材料验收标准及生产操作时应引起重视。     

12V190大功率柴油机模锻连杆断裂失效分析

本文通过对190柴油机模锻连杆上的裂纹检验分析,找到了造成该批连杆开裂的主要原因,是由于原材料中存在严重的成分偏析所致。同时指出了连杆在锻造和热处理过程中存在问题。通过这一失效事件,我们也指出了这种原材料缺陷目前在我国国家标准GB3077《合金钢结构钢》中还没有做出限制规定。希望有关单位,今后在制定原材料验收标准及生产操作时应引起重视。     

我国锻造工业炉的现状及发展趋势

阐述了铸造工业炉燃料构成，炉型结构，燃烧装置，余热利用，耐火材料及热工控制等方面的技术现状，以及煤炉改造及高性能锻造工业炉的发展趋势。     

Effect of rheological properties of catalyst slurry on the structure of catalyst layer in PEMFC

The dispersion process significantly influences the dispersion of catalyst slurry in proton exchange membrane fuel cells (PEMFCs). The particle size distribution and rheological properties of clusters in slurry directly affect the catalyst layer's coating state, surface morphology, and structure. This paper prepared four different catalyst slurries by high shear emulsification, homogenization, ball milling, and ultrasonic methods. The average particle sizes of clusters in slurry were 725, 337, 452, and 1098 nm, respectively. The rheological properties of catalyst slurry prepared by several dispersion processes are different. Amplitude scanning test demonstrates that yield stresses of slurries prepared by shear, homogenization, ball milling, and ultrasonic methods are 0.047, 0.185, 0.133, and 0.136 Pa, respectively. The viscosity of catalyst slurry is the lowest when prepared by the shear method and is the highest when prepared by the ultrasonic method, and the slurry prepared by homogenization and ball milling methods has the best thixotropy. By observing the catalyst layer, the slurry cluster prepared by the homogenization method has small particles, a strong network structure, and good thixotropy, producing a flat catalyst layer and fewer cracks. Electrochemical tests demonstrate that the catalyst layer with the smoothest surface morphology, the smallest cluster particles, and fewer cracks leads to higher polarization performance. The output voltage of the ink prepared by the homogenization method can reach 0.726 V under the condition of 1000 mA cm^?2.     

高精度离散式蓄热锻造加热炉控制系统设计

阐述了高精度离散式蓄热锻造加热炉控制系统设计及应用,详细介绍了系统的总体结构、燃烧控制策略、离散式烧嘴换向策略.现场应用结果表明,相关控制系统和控制策略的优势在高要求锻造加热炉中得以充分体现,有良好的推广应用价值.     

Thermosolutal flow in steel ingots and the formation of mesosegregates

The influence of the thermosolutal convection of the liquid steel in the solidifying core of a 3.3-ton ingot on the formation of banded mesosegregates is investigated by a multiscale solidification model. We first show how the thermosolutal flow structure in the solidifying core depends on the relation between the interacting thermal and solutal buoyancy forces and the coupling by the phase-change kinetics. We further show that banded mesosegregates are triggered by instabilities of the solidification front, that their location is determined by flow instabilities, and that their “A” or “V” orientation depends on the global direction of the flow circulation. Moreover, the results show that local remelting is not necessary to develop a channel mesosegregate. Destabilization of the mushy zone with local variations of the solidification velocity is sufficient.     

Thermoelastic deformation of three-layer combined die under steady-state temperature field

Multiple forging cycles are required to reach a steady-state temperature distribution in forging dies, which can lead to thermoelastic deformation and impact on the dimensional accuracy of the final forging components. The steady-state temperature fields of a three-layer combined die with constant, convection, conduction and convection thermal boundary conditions were determined in the present study. Thermoelastic deformation and the contact stresses between layers were directly related to geometric and material properties, external stresses and the temperature distribution. Warm/hot and cold forging case studies were studied using finite-element analysis. In warm/hot forging, the contact stress of the steady-state temperature distribution was smaller than the hypothetical non-uniform temperature distribution. During cold forging, the difference in total deformation between steady-state and uniform temperature distributions at the same temperature was 0.025 mm, which may reduce the geometrical accuracy of cold forging parts.     

Cellulose nanowhiskers separated from a bio-residue from wood bioethanol production

The aim of this study was to explore the utilization of industrial bio-residues as a source of raw material for the industrial production of cellulose nanowhiskers. The used residue, obtained from a bioethanol pilot plant, was first purified using chemical extraction and bleaching, and then separated to nanowhiskers by mechanical treatments such as ultrasonication, high-pressure homogenization as well as chemical acid hydrolysis.The chemical compositions and characteristics of the bio-residue were studied before and after purification using a TAPPI standard, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The morphology of the isolated nanowhiskers was characterized using atomic force microscope (AFM).The chemical composition of the used bio-residue was found to be 49.5 wt% cellulose, 42.1 wt% lignin and 8.4 wt% extractives. The crystallinity of the bio-residue was 14.5% and it increased to more than 73% after the purification process. The nanowhiskers isolated using ultrasonication or high-pressure homogenization had better thermal stability than nanowhiskers isolated with acid hydrolysis. The AFM study showed that a simple ultrasonication and homogenization processes resulted in nanosize whiskers with diameters in the 10-20 nm range.