感应加热淬火对45钢销轴残余应力分布和疲劳性能的影响

测试了经表面磨削、感应加热淬火45钢销轴棒状试件的表层残余应力、显微硬度和疲劳性能,并分析了精加工对残余应力的影响,最后简析了有效硬化层深度对疲劳性能影响。结果表明:试样感应淬火处理后在表层形成厚度约为3.2 mm、显微硬度平均值高达612.48 HV0.5的马氏体层,并具有较高的残余压应力;通过疲劳试验S-N数据曲线得出,较深的有效硬化层深度有利于提高销轴的韧性和抗疲劳性能。     

激光冲击强化对7050铝合金小孔结构残余应力和疲劳性能的影响

研究了激光冲击强化对7050 T7451铝合金小孔结构显微硬度、残余应力和疲劳性能的影响。结果表明:当激光能量为30 J、光斑直径ø4 mm,冲击2次时,7050 T7451铝合金显微硬度显著提高,表层硬度相对于母材提高约12%且硬化层深度可达1 mm;残余压应力幅值超过300 MPa,影响深度可达约1 mm,明显大于喷丸强化残余应力影响层深度。激光冲击诱导的残余压应力可提高疲劳裂纹的萌生抗力,其较深的残余压应力层则有利于延长裂纹的扩展寿命。激光冲击强化后小孔结构疲劳寿命相对于母材提高了4.7~17.6倍,且其疲劳寿命增益及稳定性明显优于喷丸强化。     

高温合金激光冲击处理后残余应力及裂纹分析

利用激光冲击处理技术对GH141高温合金表面进行了冲击,采用X射线衍射法对其冲击处理前后残余应力分布进行了测试,并观察了其冲击处理前后疲劳裂纹产生情况。结果发现,GH141高温合金在冲击处理前残余应力均表现为拉应力,应力值约为200 MPa,在经过激光冲击处理后残余应力均转变为压应力,应力值约为-400 MPa,且硬度提高了20%~25%。在冲击过程中,发现处理后疲劳裂纹明显减少,说明激光冲击能有效降低疲劳裂纹的萌生,提高疲劳寿命。     

大直径曲轴热处理后的残余应力分析

以巴克豪森噪声（BN）为基础,采用磁弹性应力仪测量大直径曲轴调质、定型（中间退火）、中频淬火过程的残余应力,并研究了残余应力的形成、沿截面分布规律以及对工艺的影响。结果表明,调质后曲轴表面残余应力为压应力,心部为拉应力,压应力层深约15mm;定型处理使表面压应力减少了100MPa左右,对中频硬化不利,需予以取消;中频淬火后表面残余应力为压应力,在8mm左右深度上,压应力稳定在420MPa左右,压应力总层深约13mm。     

18CrNiMo7-6钢渗碳淬火齿轮不同喷丸处理后的齿根表层应力分布

对模数20 mm的18CrNiMo7-6钢渗碳淬火齿轮经不同喷丸处理后的齿根表层应力分布进行测试,并与未喷丸时进行了对比。结果表明,在喷丸前后18CrNiMo7-6钢渗碳淬火齿轮齿根最表层均为压应力状态,从表至里均呈先升高后降低的变化趋势。未喷丸时最表层残余应力约为-75 MPa,最大残余应力出现在次表层110~120 μm处,约为-250 MPa;喷丸处理可使齿根表层残余压应力提高4~5倍,最表层残余应力在-350 MPa左右,最大残余应力出现在次表层90～110 μm处,为-900~-1000 MPa。     

碳含量及冷却速率对钢件淬火残余应力的影响

研究了直径为ø12 mm、长度为50 mm的SAE8620、SAE8625及SAE8627钢试棒淬火后表面残余应力与碳含量及冷却速率的关系。研究结果表明在渗碳淬火处理后零件表面均为残余压应力,其值大小在200~600 MPa;随着碳含量和冷却速率的增加,心部硬度值增加,表面残余压应力值减小;同种碳含量的试样心部硬度相同时,冷却速率越高,表面残余压应力的值越小;采用较低的冷却速率有利于提高表面的残余压应力。     

激光冲击功率密度对W18Cr4V钢表面性能影响的研究

采用波长1.06μm、脉宽20 ns的钕玻璃激光对W18Cr4V高速钢进行强化。研究了激光功率密度对W18Cr4V钢强化层显微硬度和残余应力的影响。结果表明:经激光冲击强化后的W18Cr4V钢奥氏体晶粒细化,细晶强化作用显著;不同的激光功率密度都能在冲击区横截面上形成由表及里的显微硬度梯度和一定深度的残余压应力层。随功率密度的提高,硬度峰值和最大残余压应力增大,硬化层和残余压应力层的深度增加。当采用3.6 GW/cm~2的功率密度时,表面硬度峰高达1125 HV0.1,表面残余压应力最大值约-220 MPa,并可获得0.8 mm左右的硬化层和1.4 mm左右的残余压应力层。     

超声冲击对Q460高强钢焊接接头残余应力及组织性能的影响

以Q460高强钢焊接试板为研究对象,采用超声冲击处理接头表面,研究超声冲击对焊接残余应力及组织性能的影响。研究结果表明:超声冲击可以有效降低焊接残余应力,并使拉应力转化为压应力;超声冲击消除了焊缝与母材过渡区域的凹坑与尖角,焊趾处变得圆滑;超声冲击细化了表层晶粒,细化层深度约120μm;超声冲击后表面显微硬度提高了40 HV0. 2,硬化层深度约2 mm。     

无损应力测试在17Cr2Ni2Mo钢汽车齿轮中的应用

对17Cr2Ni2Mo钢制汽车齿轮试件进行热处理、磨削加工及喷丸强化,借助无损残余应力测量设备与显微硬度测试议测试了各处理工艺下试件表层残余应力与显微硬度。结果表明,常规的渗碳淬火+回火处理工艺可保证较高的表层残余压应力与力学性能,磨削加工会恶化残余应力分布,降低疲劳性能,而喷丸强化则可彻底改变表层原始应力分布状态,有利于提高抗疲劳性能。     

超声波冲击技术对AA6061-T6空蚀行为的影响

AA6061-T6铝合金因较高的比强度、良好的可成型性广泛应用于汽车工业中,但较差的空蚀性能极大的降低了其使用寿命。利用超声波冲击技术在AA6061-T6表面制备了塑性形变强化层,研究塑性形变强化层的微观组织、残余应力及显微硬度分布和抗空蚀性能。结果表明,超声波冲击强化后铝合金表面择优取向由原始的(200)转变为(111),并形成约140μm塑性变形层。与未强化试样相比,强化试样表面显微硬度提高了80.7%,并形成140μm硬化层;表面植入残余压应力达到-259 MPa,残余压应力层深达到700μm。超声波冲击强化处理后的空蚀性能提高2.36倍;空蚀表面形貌分析表明强化后试样空蚀机制由韧性断裂转变为脆性断裂和疲劳破坏。研究表明超声波冲击强化后试样表面晶粒细化、择优取向转变、硬度提高以及较高残余压应力等增强了材料的抗空蚀性能。     

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.     

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.     

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.     

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.