渗氮齿轮硬化层设计及接触疲劳性能研究

采用滚子接触疲劳试验方法,测定了离子渗氮层在不同失效概率下的振幅A(τyz/HV)m ax值,以此作为齿轮渗氮层强度设计依据。通过对试验齿轮的接触应力有限元分析,得出正交切应力τyz沿深度方向上的分布,依照接触疲劳强度判据,设计出了齿轮渗氮层的硬度分布曲线,运用适当的离子渗氮工艺,实现预期设计的硬度,最后通过齿轮接触疲劳台架试验,验证所设计的渗氮硬化层是可靠的。     

渗氮曲轴的疲劳寿命和质量控制

本文分析了大功率柴油机曲轴失效的一般规律和气体渗氮对提高曲轴疲劳寿命的影响,认为渗氮是提高曲轴疲劳寿命的有效途径。在分析影响渗氮曲轴疲劳寿命因素的基础上,特别指出了对渗氮层过量磨削的危害。为了减少或不磨削渗氮轴颈,需要严格控制渗氮变形。文中总结了国内8大厂家各种控制曲轴渗氮变形的方法和效果。指出,在卧式炉或井式炉中处理,都可能严格控制曲轴的变形,从而得以生产高疲劳强度的大功率柴油机曲轴。     

铝型材挤压模具失效分析

H13钢模具在生产铝型材的过程中出现早期软化、变形、开裂和磨损等问题，采用化学成分分析、硬度测试和显微组织观察等检测方法，对模具失效原因进行分析。结果表明:该模具在渗氮前进行的淬火和回火工艺不合理，存在少量夹杂和未溶解的碳化物，使其整体韧性不高；其渗氮层厚度较薄，且渗氮层硬度偏低，组织不稳定，渗氮层与基体的结合力较差，加剧模具渗氮层的剥落和磨损。建议从模具的热处理工艺和渗氮工艺方面进行优化来提高其硬度和冲击韧性，从而延长模具的使用寿命。     

喷丸强化对渗氮40Cr和30CrMo钢疲劳性能的影响

对40Cr和30CrMo钢进行渗氮、喷丸等单一强化和渗氮后喷丸的复合强化处理,测定了钢件表层的残余应力与显微硬度,采用升降法确定了1×10 7循环周次下的疲劳强度.结果表明,渗氮、喷丸和渗氮 喷丸表面强化均可提高40Cr和30CrMo钢疲劳强度,但渗氮后喷丸复合强化的效果最佳.对疲劳试样的断口分析表明,调质未表面强化试样的疲劳裂纹源于表面,而强化试样的疲劳裂纹源于强化层下的次表层.     

42CrMo合金钢螺栓的断裂失效分析

通过宏观和微观断口形貌观察、化学成分分析、力学性能检测、金相观察、渗氮层检查等方法对42CrMo合金钢的螺栓断裂原因进行分析。结果表明:螺栓断裂属于大应力集中高应力双向弯曲疲劳断裂,裂纹起源于螺栓退刀槽靠近螺杆端圆角处;由于表面渗氮硬度高,韧性和抗疲劳性能下降,承载大冲击载荷能力减弱,引起螺栓断裂失效。改进工艺后,螺栓圆角处不做渗氮强化,螺栓没有发生断裂失效。     

弹簧低温渗氮层组织与疲劳性能研究

研究了５０ＣｒＶＡ钢油淬火弹簧的低温离子渗氮及低温气体氮碳共渗处理工艺，观察并分析了渗氮层组织形态及疲劳性能。结果表明，低温离子渗氮可显著提高弹簧的疲劳寿命。最后给出了表面强化弹簧的剪切疲劳模型。     

TC4钛合金螺栓真空渗氮组织及性能

采用真空技术对TC4钛合金螺栓进行表面渗氮。运用金相显微镜、XRD、显微硬度计、磨损试验机及疲劳试验机研究了渗氮层的显微组织和性能。在相同条件下进行磨损及微动疲劳试验。结果表明,钛合金螺栓经820℃真空渗氮10 h后,渗氮层物相主要由Ti N、Ti2Al N和Ti3Al组成,获得了由氮化物层和氮扩散区组成的致密渗氮层。表面硬度为1100~1200 HV,与基体硬度相比,提高了近3倍,硬化层深度达60~70μm。渗氮试样磨损失重为未渗氮试样的1/3,表面磨痕细密,平均微动疲劳寿命提到了20.2%。TC4钛合金螺栓经真空渗氮后,硬度、耐磨性和微动疲劳寿命得到了明显改善。     

球铁曲轴加氧渗氮工艺研究

球铁曲轴常常由于渗氮层薄、质量不稳定而引起断裂失效，本课题研究了球铁曲轴加氧渗氮工艺。对球铁试样经570℃、580℃，不同氨气流量和氧加入量渗氮4h后的表面硬度、渗层深度及渗层组织进行分析，结果表明，加氧渗氮可获得比常规气体氮碳共渗更高的表面硬度和渗层深度。优选出的适合于球铁曲轴的加氧渗氮工艺为：570℃保温4h，氨气流量2000L／h，氧气流量10L／h，炉压35mm水柱；或580℃保温4h，氨气流量1800L／h，氧气流量10L／h，炉压35mm水柱，二种工艺均可获得深度超过0．20mm、表面硬度600HV0．1以上的渗层。     

渤海某油田油管接箍腐蚀开裂原因与建议

通过化学成分分析、硬度测试、金相检验、冲击韧性测试、拉伸性能测试、渗氮层厚度测试等方法,对渤海某油田A10井某油管腐蚀失效原因进行了全面研究。结果表明:由于酸化或其他井下作业残留介质、管柱渗氮处理工艺不良等因素造成渗氮层破损导致腐蚀失效,建议加强酸化等施工作业对油管的腐蚀保护以及渗氮油管的质量控制。     

氨水浓度对38CrMoAl钢液相等离子体电解渗氮层显微组织及性能的影响

在不同氨水浓度的电解液中，采用液相等离子体渗透技术在38CrMoAl钢表面制备了渗氮层。采用光学显微镜(OM)、扫描电镜(SEM)和X射线衍射仪(XRD)等对渗氮层的显微组织、相组成进行了观察和分析，并采用Parstat2273电化学工作站测试了渗氮层的耐蚀性能，并对其显微硬度和耐磨性进行了测试，研究了氨水浓度对38CrMoAl钢液相等离子体渗氮显微组织与性能的影响。结果表明：随着氨水浓度的增大，渗氮层中的白亮层厚度呈增加趋势，分布着针状的氮化物和细小碳化物的扩散层厚度和渗氮层最大显微硬度值呈先增加后降低的趋势；当氨水浓度为60%时，渗氮层厚度达160μm,其中扩散层为112μm,渗氮层硬度最高为1023 HV0.1,约是基体硬度的3.5倍；渗氮层主要以Fe₂N、Fe₃N相等为主；渗氮层的耐磨性能和耐腐蚀优于基体。     

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.