异种钢闪光对焊接头蠕变断裂力学行为

分别钢闪光对焊制备的高强匹配（ＢＷ－ＷＨ－ＢＬ）、低强匹配（ＢＨ－ＷＬ－ＢＭ）和中强匹配（ＢＬ－ＷＭ－ＨＢ）的;宏观力学不均匀异种钢接头进行了蠕变及蠕变断裂,试验,并用有限元方法分析了不同匹配接头蠕变断裂的力学因素。结果表明,高强匹配和低强匹配接头均沿头邻近焊缝界面的低强度母材或焊缝侧发生断裂,并怕特征;中强匹配接头蠕变断裂位置在远离焊缝界面的低强度母材区,呈延性断裂性质。应力三轴性是控制高强匹配     

马氏体/贝氏体耐热钢焊接接头的界面蠕变损伤行为

采用脉冲氩弧焊接工艺、高温加速模拟、高温持久实验研究了不同焊缝蠕变强度匹配条件下马氏体耐热钢9Cr1MoVNbN与贝氏体耐热钢12Cr2MoWVTiB异种钢焊接接头的高温强度、界面蠕变损伤及破坏特征.研究结果表明,焊前523 K预热、焊后1023 K×1 h回火条件下,接头的力学性能优异.加速模拟运行500,1000和1500 h后低匹配焊接接头的界面蠕变损伤最严重,发生了界面蠕变断裂,早期失效倾向较大;中匹配接头的蠕变损伤最小,仅发现个别孤立蠕变孔洞,早期失效倾向最小,中匹配接头在923 K下的持久强度(σ105)与低匹配接头比较接近;高匹配接头在923 K下的持久强度(σ105)最低,蠕变孔洞几乎连成裂纹,蠕变损伤和早期失效较大.因此,对于上述异种钢焊接接头采用中匹配焊缝较为合理.     

铁素体-奥氏体异种钢接头的界面组织及力学性能

为提高电站锅炉过热器铁素体－奥氏体异种钢焊接接头的高温蠕变断裂强度和服役寿命，设计了专用的镍基填充材料及组合焊接接头。通过对不同焊缝接头的高温蠕变力不试验，焊缝界面组织变化分析，碳扩散和热应力的测试分析，认为在高温低力的条件下，接头焊缝界面及热影响区碳元素扩散迁移和碳化物聚集是影响接头蠕变断裂强度的重要原因。     

铁素体-奥氏体异种钢接头高温失效原因的分析

通过用镍基合金、奥氏体和铁素体填充材料焊接的铁素体-奥氏体异种钢接头的蠕变断裂试验结果表明,材料之间的蠕变强度不匹配是异种钢接头高温运行中过早失效的主要原因。为了改善铁素体钢和奥氏体钢之间蠕变强度差别太大的问题,接入一段蠕变强度介于两者之间的过渡段,结果可使异种钢接头的蠕变断裂强度(寿命)达到铁素体同种钢接头的水平。     

焊缝蠕变强度对马氏体/贝氏体异种钢接头界面蠕变损伤的影响

采用脉冲氩弧焊接工艺、高温加速模拟、扫描电镜观察研究了不同焊缝蠕变强度匹配条件下,马氏体耐热钢(9Cr1MiVNbN)与贝氏体耐热钢(12Cr2MoWVTiB)焊接接头的界面蠕变损伤、破坏特征及早期失效倾向.结果表明,焊前预热250℃,焊后回火750℃×1 h条件下,加速模拟运行500,1 000,1 500 h后低匹配接头中焊缝/贝氏体钢界面的蠕变损伤最严重,发生了界面蠕变断裂,早期失效倾向较大;而高匹配接头中焊缝/贝氏体钢界面的蠕变孔洞几乎连成裂纹,蠕变损伤和早期失效较大;而中匹配接头的界面蠕变损伤程度最轻,仅发现少量孤立蠕变孔洞,早期失效倾向最小.     

火电站用T23/TP316H异种金属焊接接头服役损伤分析

通过试验研究分析了服役后的高温蒸汽管道中T23/TP316H异种金属焊接接头的微观组织、成分和氧化情况。结果表明,在540℃/17 MPa条件下服役10万h后,TP316H钢侧虽会被氧化,但未发现明显的会导致接头早期失效的潜在危险因素;T23钢侧会出现沿焊缝/热影响区界面的氧化,并出现了沿界面的开裂。T23钢与镍基焊缝金属的界面氧化损伤与界面两侧热膨胀系数、高温蠕变强度差异及界面附近的硬度梯度耦合后,很可能诱发界面失效,增加接头早期失效风险。与此同时,T23钢侧未发现蠕变、碳迁移软区等常见的界面失效弱化因素,所以界面氧化损伤是T23/TP36H异种金属焊接接头的主要损伤模式。     

超超临界机组奥氏体/马氏体异种钢接头蠕变数值模拟

采用有限元方法对超超临界火电机组中新型奥氏体耐热钢HR3C/马氏体耐热钢T91异种钢接头在600℃/42.26 MPa内压作用下的最大蠕变主应力、von Mises等效应力和应力三轴度进行了数值模拟.结果表明,对于HR3C/T91异种钢接头,最大主应力峰值位于焊缝/T91界面附近区域,蠕变孔洞易于在焊缝/T91界面区域...     

T92/HR3C异种钢接头的蠕变损伤演化

对T92/HR3C异种钢焊接接头进行温度为650 ℃、应力为90 MPa的系列蠕变中断试验,利用光学显微镜、扫描电子显微镜对经过不同蠕变寿命分数试样的显微组织和蠕变孔洞损伤进行了观察与定量,并测试了接头蠕变断裂后的硬度分布. 结果表明,T92/HR3C异种钢接头断裂在T92侧细晶粒热影响区(FGHAZ),断裂方式为IV型开裂,接头镍基焊缝和HR3C侧未见孔洞损伤. 接头T92侧FGHAZ的蠕变损伤过程可划分为3个阶段,在蠕变初期(< 40%t_f,t_f为断裂寿命),FGHAZ的孔洞数量很少;在蠕变中期(60%t_f ~ 80% t_f),蠕变损伤快速积累,孔洞数量急剧增加,并出现少量微裂纹;在蠕变寿命的后期(> 80%t_f),大量微裂纹形成并扩展形成宏观裂纹. 接头中T92侧FGHAZ的硬度最低,蠕变性能劣化最严重,加上在高温蠕变过程中存在Laves相粒子的析出和长大,促进了蠕变孔洞损伤的形成.     

焊接接头的强度

利用低温破断方法对不锈钢焊接接头蠕变断口形貌的分析，Fe3Al与Q235钢异种材料扩散焊的界面剪切强度，薄壁6061铝合金TIG焊接结构强度研究，铝-锂合金焊接接头金属的强度和韧性。[编者按]     

铝合金与钢的电阻凸塞焊

采用电阻凸塞焊新方法对A6061铝合金和Q235低碳钢进行焊接,观测了接头微观形貌并检测了接头特征区域的化学成分,对接头的力学性能进行了测试。结果表明:在电阻凸塞焊中,以钢/钢同种材料界面取代铝/钢异种材料界面实现了接头的可靠连接,避免了在焊接接头产生较多脆性的金属间化合物。与普通点焊的接头相比,电阻凸塞焊接头的力学性能有明显的提升;工艺孔直径为10.0 mm时,接头最大抗剪力达到6.28 kN,接头断裂属于塑性断裂。对于铝合金/钢异种材料的连接,电阻凸塞焊是一种有效的工艺方法。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.