美国FORGE计划犹他州干热岩开发示范项目进展综述

21世纪是全球能源获取方式发生重要变化的时代。现有以煤炭、石油、天然气等传统资源为基础的能源正在逐渐被风能、太阳能、生物质能、地热能等环境友好、低排放的绿色能源所取代。干热岩是一种不含原生水(或含少量水但不能流动)的高温地热资源,可通过水力刺激改造形成增强型地热系统储层,从而提取数量相当可观的地热能。本文以美国能源部正在组织实施的FORGE计划犹他州干热岩示范项目为研究对象,综述了项目在场地地质条件表征、基础设施建设等方面取得的主要进展与成果,总结了项目在高温硬岩钻井、储层建造、微震监测等方面取得的广泛且深入认识,从统筹部署、组织实施、场地表征和设施建设、关键技术装备突破、数据共享等方面提出了值得我国借鉴参考的具体实践。

Effect of forging on the microstructure and texture of a high Nb containing γ-TiAl alloy

The effect of forging on the microstructure and texture evolution of a high Nb containing Ti-45Al-7Nb-0.3W(at.%)alloy was investigated by X-ray diffractometer(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).The results show that the as-cast alloy is mainly composed of α_(2)/γ lamellar colonies with a mean size of 70μm,but the hot-forged pancake displays a near duplex microstructure(DP).Kinking and bending of lamellar colonies,deformation twinning and dynamic recrystallization(DRX)occur during hot forging.Meanwhile,dense dislocations in theβphase after forging suggest that the high-temperature β phase with a disordered structure is favorable for improving the hot-workability of the alloy.Unlike the common TiAl casting texture,the solidification process of the investigated as-cast alloy with high Nb content is completely via the β phase region,resulting in the formation of a<110>γ fiber texture where the<110>γ aligns parallel to the heat-flow direction.In comparison,the relatively strong<001>and weak<302>texture components in the as-forged alloy are attributed to the deformation twinning.After annealing,static recrystallization occurs at the twin boundary and intersections,which weakens the deformation texture.

Simulation-Based Investigation of Crack Formation in Forged MB15 Magnesium Alloy

In the process of riveting an MB15 forging die,cracks were discovered emerging along the longitudinal direction and near the riveting hole.Through fracture analysis,microscopic observation,energy spectrum analysis,metallographic examination,and hardness test,the properties and causes of the cracks are discussed.The results indicate that the cracking type is intergranular brittle cracking,occurring during the forging stage.Furthermore,the recrystallization at the crack site is found to be incomplete,which is attributed to the low deformation temperature.

基于Forge的KD锻造法自动化仿真

根据KD锻造法的工艺特点,将KD锻造法工序分解成布砧、压下、翻转、进给四个工步,并循环往复。在此基础上,通过Forge有限元模拟软件匹配KD锻造法工艺参数,分析变形过程中关键指标的动态变化,验证KD锻造法自动化生产的合理性和可行性,为轴类锻件自动化生产提供数据支撑。

Microstructures and mechanical properties of 2014 aluminium alloy forgings made by a new process

The triangular 2014 aluminium alloy forgings were made by a new process and the traditional process. The results showed that the mechanical properties of the forgings made by the new process are far higher than that in the standard of GB223 84, and also higher than that in the standard of EL/53MI 94; moreover, the mechanical properties are almost the same in each direction, and anisotropies are very small. The grains and 2nd phases were analyzed by using TEM and SEM, the results indicate that very fine grains (3～6 μm)appear in an approximately isometric way, and a large number of 2nd submicrophases(0.05～0.15 μm) disappear in no apparently preferred orientation distribution because the new process involves multidirectional heavy plastic deformation (λ=12), solution(500 ℃/400 min) and ageing(165 ℃/10 h) heat treatments for a long time at high temperatures. These refined grains, 2nd submicrophases and their almost homogeneous distribution can make it possible for the forgings to display high mechanical properties.

Manufacturing of ultra-large plate forgings by unfolding and flattening of thick cylinders

Ultra-large plate forgings are foundation of heavy machinery,but many parts of the type cannot be made by conventional technologies due to the characters of extreme manufacturing in terms of size and quality requirements.This paper introduced a systematically method called cylinder unfolding method(CUM)for producing large plate forgings,by using a serial of operations including“splitting”,“unfolding”,and“flattening”of a thick cylinder obtained from saddle forging.The technological route of CUM was presented in detail with an example of plate forging with the horizontal sizes of 6100 mm and thickness of 300 mm.The deformation features of saddle forging for fabricating transitional cylinders were analyzed,and then the subsequent handling steps including splitting,unfolding and flattening of the cylinder,as well as the auxiliary processing,were addressed.The practice proved that CUM can provide an efficient way for manufacturing ultra-large plate forgings and meet the strict requirements in geometry and mechanical performance,without highly increasing the investments of forming equipment and tooling.

STUDY ON THE FORMATION OF DEFECTS IN DURALUMIN FORGINGS

The mechanism of forming defects in 2024. 7075 series aluminium alloy forgings has been studiedby means of metallography. EDAX. SEM etc. The defects are divided into two types by their appearance.needle-shaped and flake-shaped. The mechanism of them forming is discussed. It has been testified that thedefects result from hydrogen or oxide film. The defects can be prevented by controlling the hydrogen contentin the melt and keeping oxide film from involving.

Effect of heat treatment on the microstructure and mechanical properties of a multidirectionally forged Mg-Gd-Y-Zn-Zr-Ag alloy

Multidirectional forging(MDF)was successfully applied to fabricate large-size Mg-Gd-Y-Zn-Zr-Ag alloy in this work and effects of T4,T5 and T6 treatments on the microstructure and mechanical properties of the as-forged alloy were analyzed.Results show that dynamic recrystallization(DRX)occurs and second phase particles precipitate along the grain boundary during the MDF process.After annealing treatment(T4),the volume fraction and size of dynamic precipitates slightly increase at a lower temperature(430℃)compared with those of MDFed sample,while they are dissolved into theα-Mg matrix at a higher temperature(450℃).At the meantime,short plate-shaped long-period stacking ordered(LPSO)phases are observed in the DRX grains of the MDFed sample and then dissolved into theα-Mg matrix during annealing at both temperatures.Typical basal texture is identified in the MDFed sample,but the basal pole tilts away from final forging direction and rare-earth texture component with<1121>orientation parallel to penultimate forging direction becomes visible after annealing.The T6 sample annealing at 430℃for 4 h and ageing at 200℃for 34 h exhibits the superior strength and ductility in this study.The ultimate tensile strength,tensile yield strength and elongation to failure,which is 455 MPa,308 MPa and 7.7%,respectively,are overall improved compared with the directly-aged(T5)sample.This paper provides a superior heat treatment schedule to manufacture high-performance large-scale Mg-Gd-Y-Zn-Zr-Ag components for industrial production.

MICROSTRUCTURAL EVOLUTION AND CONTROL IN SUPERALLOY FORGINGS

Optimum properties of high temperature superalloys are derived from interactions of the composition,thermomechanical deformation, and heat treatment.Nickel-base alloys contain a variety of alloying elements in a large number of combinations to produce various desired effects. The general characteristics of any specific nickelbase superalloy is determined by composition.The control of the microstructure in wrought processed superalloys can further influence the resultant component properties.The relationship between microstructure and properties is key in advanced design and manufacture of turbine engine components, and requires extensive alloy and process characterization to achieve desired results.Various forging methods have been developed and employed throughout the years to process superalloy components.Hammer forging, Press forging,and advanced isothermal press forging equipment and processes have been designed and manufactured to process speciality metals which often have very narrow processing windows.Combination processes have also been introduced into turbine engine applications,which result in a hybrid of resultant structures and properties.One such speciality,combination process is the Ladish Iso Con process which utilizes isothermal forging and conventional forging to achieve unique properties not matched by any other single process.Ladish utilizes forging presses for conventional forging, hot-die forging and for isothermal forging, in addition to hammers and ring rolling mills for wrought processing.This wide range of equipment allows flexibility in process design and optimization.Variations in temperature, strain and strain rate have been shown to significantly influence resultant grain sizes and microstructures.Tools are being developed to allow forging processes and specific forging parameters to be evaluated and optimized with regard to final microstructure before shop triale are required. Sophisticated finite element method (FEM) models are allowing the design of forging processes on computers rather than by iterative trial and error methods.

Effect of nitrogen content on the microstructure and mechanical properties of titanium-bearing nonquenched and tempered steel after hot forging

The microstructure and mechanical properties of titanium(Ti)-bearing medium-carbon nonquenched and tempered steel with different nitrogen content before and after hot forging were investigated through smelting,forging,and laboratory tests.The results show that the grain size of nonquenched and tempered steel was gradually refined,and the ferrite content gradually increased with an increase in nitrogen content.The grain size of the material with low nitrogen content increased abnormally,and its impact properties significantly decreased after hot forging.The grain size of nonquenched and tempered steel with higher nitrogen content was slightly larger than that before forging,and the tensile and yield strength increased,but the impact toughness was not significantly reduced.The Ti-bearing nonquenched and tempered steel showed better strength and toughness after hot forging with the addition of 0.010%0.015%nitrogen.

铸牢中华民族共同体意识融入民族地区语言教育对策研究

民族地区语言教育发展是推动各族群众交往交流交融,促进民族团结的重要举措。民族地区只有不断加强国家通用语言文字教育才能更好地适应当前阶段的客观需要,加强民族间的交往交流交融,实现书同文、语同音、心相通、情相融。文章基于民族地区通用语言教育对于铸牢中华民族共同体意识的重要意义,通过梳理既有文献及研究成果,了解当前民族语言教育发展现状,就部分民族地区语言教育存在的突出问题,提出了加强语言教育师资队伍、加大语言教育投入力度、推广普及国家通用语言文字、增强课程思政在语言教育课堂的融合程度四条策略,并认为在民族地区推广普及国家通用语言文字,要开拓创新,多措并举,多管齐下,切实解决当前存在的问题,加快推进民族地区语言教育进程,以语言相通促进各族群众的沟通交流和国家认同,进而铸牢中华民族共同体意识。

铸牢中华民族共同体意识的多重叙事建构

铸牢中华民族共同体意识必须做到“深”“细”“实”“活”,将宏大的国家话语进行“降维法”实践与应用,突出人民群众在推动民族历史发展与现代化建设中的主体地位,以普通大众为主体的小叙事作为建设共有精神家园的突破口,弥合政府叙事的风格单一性、概念抽象性、宣传垂直性的缺漏。要贯通以人民群众为主体的小叙事与国家统一、社会安定的宏大叙事,促使大众通过日常叙事主动参与中华民族共同体建设的热情,使民间叙事与国家话语相得益彰。在大叙事与小叙事的循环互构中,确证与阐释中国特色发展的成效和道路优势。在故事的书写、传阅和共议中加深对中华民族伟大复兴的理解和责任承担,最终将铸牢中华民族共同体意识转化为自觉自强的行动实践。

网络空间铸牢中华民族共同体意识的逻辑理路

网络空间拓展了铸牢中华民族共同体意识的实践场域,同时也面临着时空挤占、负面要素生发和实践成效不集中等问题。网络空间铸牢中华民族共同体意识,以网络空间的民族互嵌和中华民族共同体符号化为理论基础。通过空间拓展,网络空间实现了中华民族共有文化创造、推进各民族共同富裕和强化中华民族共同体认同,由此推进铸牢中华民族共同体意识。针对风险要素,网络空间借助双重空间协同、网络民族工作和仪式传播,形成了网络空间铸牢中华民族共同体意识的互补机制、修正机制和强化机制。

大党独有难题的认知逻辑与破解之道

时刻保持解决大党独有难题的清醒和坚定,中国共产党方能行稳致远。党以整体规模大、历史跨度大、志向抱负大等显著性特征展现“大的样子”,大党基于应有的“大的担当”肩负党内治理、国家治理、社会治理等治理任务。中国共产党作为大党,要实现高效能治党治国,必须从思想理念、政治整合、能力提升、精神状态、防错纠错、生态营造等方面剖析面临的独有难题,并给出有针对性的治理路径。大党独有难题的终极破解之道,依赖“大党之能”,借助能力涵养从领导权威、思想指南、本领本事、斗争精神、自我革命、人民支持上形成一揽子行动方略。

基于混晶评价的大锻件热锻晶粒组织演变

以大型锻件超超临界转子用12%Cr耐热钢为研究对象,采用拔长实验和数值模拟相结合的方式,探究了大锻件热锻过程晶粒组织演变情况。研究表明:热锻后坯料横截面晶粒不均匀性受锻造温度、锻比以及上模压下速度综合影响,小锻比和较低锻造温度与大锻比和较高锻造温度均可改善晶粒不均匀性。基于此,通过拟合得到了12%Cr耐热钢热锻过程坯料横截面晶粒不均匀性与锻造工艺参数之间的量化关系模型;针对大锻件“因大而生”的混晶问题,在现有混晶评价方法的基础上,提出了一种普适性更好的混晶评价方法,即采用统计学方法划分各小组,以每小组晶粒弦长和占总弦长的频率为基础,分别确定大、小晶粒分界组进行评价,对比拔长实验后的混晶组织演变规律验证了该方法的优越性。

超大直径铝合金环形锻件轧胀成形工艺与装备关键技术研究

介绍了重载火箭用铝合金大型环形锻件的制作工艺,重点分析了径轴向数控轧制环形锻件的制作工艺。介绍了大型环形锻件轧制和胀形结合成形的制作工艺,采用有限元模拟了Φ10和Φ1.2 m环形锻件的轧制和胀形结合成形工艺过程,并对Φ1.2 m环形锻件的轧制和胀形成形过程进行了试验验证。结果表明:轧制和胀形结合的成形工艺技术能有效地改善产品组织,使组织更致密,提高了产品的晶粒度;轧制和胀形工艺技术能有效地提高产品的屈服强度,从而提高产品的使役性能。胀形工艺对产品有明显的整形作用。在此基础上提出Φ10 m环形锻件径轴向数控轧制和液压胀形结合的成形工艺。

全面理解中华民族共同体的历史逻辑

《中华民族共同体概论》教材是第一部全面系统阐释习近平总书记关于加强和改进民族工作的重要思想的统编教材。《中华民族共同体概论》教材全面系统论述了中华民族共同体的基本概念、理论体系,首次完整清晰地将中华民族发展的历史逻辑展现出来,充分证明了“一部中国史,就是一部各民族交融汇聚成多元一体中华民族的历史,就是各民族共同缔造、发展、巩固统一的伟大祖国的历史”这一重要论断的科学性。深入理解中华民族的历史逻辑,踏实推进教学科研服务于党和国家民族工作的主线,进一步铸牢中华民族共同体意识。

整体式副车架液态模锻及其性能

液态模锻是铝合金件高性能成型的先进工艺,文章将液态模锻技术用于整体式副车架成型,着重研究液锻工艺方案和液锻副车架性能的均匀性。模拟研究表明,单浇道液锻比设有辅助浇道的液锻汇流位置少、表面质量高、工艺出品率高。试生产发现,利用广州和德轻量化成型技术有限公司设计制造的HVSC2500T卧式液态模锻机进行A356.2铝合金副车架的单浇道液锻,能够获得完整无缺的副车架,本体取样拉伸强度可达320 MPa,延伸率达11.12%。但是,在远离浇道和存在汇流的位置普遍存在夹渣缺陷,副车架强度和塑性都较低。