不同温度回火后30MnB5热成形钢的EBSD研究

将30MnB5热成形钢采用淬火+回火处理,利用电子背散射衍射(EBSD)技术研究了淬火态和不同温度回火后马氏体变体与母相的取向关系及其取向差变化,采用单个原奥氏体晶粒区域做出的马氏体{100}极图,并结合等密度线极图的方法对马氏体变体与母相的取向关系进行了判定.结果表明,30MnB5热成形钢淬火后得到的马氏体变体与母相的取向关系更接近N-W关系,实际极点分布在理论极点周围,并且经不同温度回火后,马氏体变体与母相的取向关系没有明显改变,但变体数目有减少的趋势.淬火态和不同温度回火后马氏体变体的取向差都主要分布在5°以下和50°以上,随着回火温度的升高,小于5°的小角度晶界略微减少,但仍占较高的比例,而大于50°的大角度晶界则呈上升趋势.这些小于5°的小角度晶界主要存在于马氏体变体内部,源自马氏体板条间的取向差,是导致不同马氏体变体间的角度离散分布在理论值周围的主要原因.     

循环淬火-回火处理对90CrMnTi钢冲击韧性的影响

采用OM、SEM、TEM和XRD等分析方法,研究了90CrMnTi钢经780℃淬火(1~3)次和180℃回火处理后的组织和性能,分析了循环淬火-回火处理对冲击韧性的影响。研究表明,循环淬火显著改善了90CrMnTi钢的冲击韧性,但对其硬度的影响较小。经3次淬火后其晶粒尺寸从1次淬火的约18μm减小到3μm,马氏体片的宽度明显变窄,未溶碳化物减少和残留奥氏体量增加。宽度20~70 nm的薄膜状残留奥氏体分布于马氏体片间或马氏体片与碳化物的交界处,且与相邻马氏体满足K-S或NW位向关系。90CrMnTi钢冲击韧性显著提高的根本原因是循环淬火-回火处理所致的晶粒超细化、马氏体片细化和碳化物减少及残留奥氏体量增加的综合作用的结果。     

Ni含量对淬火态含Cu时效钢显微组织的影响

采用扫描电镜、透射电镜和电子背散射衍射等研究了Ni含量对淬火态含Cu时效钢显微组织和精细结构的影响。结果表明,随着Ni含量增加,含Cu时效钢显微组织由贝氏体组织逐渐向马氏体组织转变,显微硬度增加;原奥氏体晶粒尺寸随Ni含量增加略有增加,但马氏体板条宽度略有减小,马氏体变体与原奥氏体晶粒取向关系符合K-S关系。     

两相区淬火对10Ni5CrMo钢组织与性能的影响

研究了10Ni5CrMo钢经调质处理和淬火 两相区淬火 回火(QLT)热处理后的组织与性能.结果表明,1ONiSCrMo钢经两相区淬火处理后,得到板条状的二次回火马氏体 铁素体的混合组织,并且在板条边界及板条内部析出逆转变奥氏体,该逆转变奥氏体与基体遵从K-S关系.10Ni5CrMo钢经QLT处理后改善了钢的回火稳定性,屈强比降低,尤其是低温韧性显著提高.随着回火温度的升高,逆转变奥氏体的含量增多.稳定的逆转变奥氏体提高了低温韧性.     

PHASE TRANSFORMATION AND MECHANICAL PROPERTIES OF MARAGING STAINLESS STEELS

研究了两种成分的马氏体时效不锈钢。测定了钢中回火奥氏体含量与回火温度、回火时间、淬火温度的关系.两种钢经850℃淬火后回火,奥氏体含量随回火温度升高开始增加随后又下降,在610℃左右达到峰值约24％。奥氏体含量随回火时间的延长而增加,是一扩散控制过程。奥氏体含量与淬火温度有明显关系。在同一温度(580℃)回火,奥氏体含量与淬火温度之间存在最低值:两种钢各在1000℃和950℃淬火后回火,其奥氏体含量下降至零值附近。 测定了不同淬火温度、回火温度、回火时间对钢中微观应变△a/a的影响。经不同热处理后,△a/a的变化与马氏体二奥氏体相变过程有关。分析了钢的组织与力学性能之间的关系。回火奥氏体的存在使强度下降,估计10％的奥氏体使强度损失约10kg/mm~2。但较软的回火奥氏体沿板条状马氏体边界形成改善钢的韧性,使冲击韧性a_K提高。从钢的强度和韧性的配合考虑,采用适当的回火处理以产生5—10％稳定的回火奥氏体是可取的。     

两种马氏体时效不锈钢的相变和力学性能

研究了两种成分的马氏体时效不锈钢。测定了钢中回火奥氏体含量与回火温度、回火时间、淬火温度的关系.两种钢经850℃淬火后回火,奥氏体含量随回火温度升高开始增加随后又下降,在610℃左右达到峰值约24%。奥氏体含量随回火时间的延长而增加,是一扩散控制过程。奥氏体含量与淬火温度有明显关系。在同一温度(580℃)回火,奥氏体含量与淬火温度之间存在最低值:两种钢各在1000℃和950℃淬火后回火,其奥氏体含量下降至零值附近。测定了不同淬火温度、回火温度、回火时间对钢中微观应变△a/a的影响。经不同热处理后,△a/a的变化与马氏体二奥氏体相变过程有关。分析了钢的组织与力学性能之间的关系。回火奥氏体的存在使强度下降,估计10%的奥氏体使强度损失约10kg/mm~2。但较软的回火奥氏体沿板条状马氏体边界形成改善钢的韧性,使冲击韧性a_K提高。从钢的强度和韧性的配合考虑,采用适当的回火处理以产生5—10%稳定的回火奥氏体是可取的。     

65MnCr耐磨钢的连续冷却转变和组织性能

设计了一种新型65MnCr耐磨钢,并对其CCT曲线进行测定,研究该钢不同冷速下的组织变化及热处理后的组织性能.结果表明,65MnCr钢的临界冷却速度在1～3℃/s之间,Ms点184℃,具有很高的淬透性,完全淬透后,马氏体硬度达64 HRC,淬硬性好.φ130 wn柱状试样经水淬+自回火后,冲击吸收能量在15 J以上,从表面至心部,硬度分布均匀,均在48 HRC以上,组织依次为回火马氏体、马氏体+块状(马氏体+奥氏体)组织、马氏体+粒状贝氏体+块状(马氏体+奥氏体)组织,是一种理想的可供大尺寸构件用耐磨材料.     

热处理对超高强度20Mn2Cr汽车钢组织和性能的影响

研究了热处理工艺参数对20Mn2Cr钢显微组织和性能的影响规律,并采用扫描电镜、透射电镜、电子背散射衍射技术等研究了不同奥氏体化温度和回火温度下实验钢中的马氏体组织特征和碳化物析出形貌.结果表明,实验钢经900℃奥氏体化处理时可以保证较小的原奥氏体晶粒尺寸及细小的马氏体板条束宽度;550℃再结晶退火可以进一步细化原奥氏体晶粒尺寸及马氏体板条束宽度;淬火后的回火处理有利于Cr碳化物粒子的析出.通过调整热处理工艺,20Mn2Cr钢可以获得1000～1700 MPa级的系列超高强度,同时可以实现超高强度与高塑性的良好匹配.     

热变形对35CrMo钢淬火马氏体晶体学特征的影响北大核心CSCD

通过热压缩实验获得不同应变下35CrMo钢的淬火马氏体组织。基于电子背散射衍射(EBSD)测试技术研究了热变形对35CrMo钢淬火马氏体晶体学特征的影响,重点分析了不同变形量下奥氏体晶粒尺寸及马氏体变体组合特征的变化。研究结果表明:多轮动态再结晶的出现造成了高温真应力-真应变曲线的多峰变化,且第1轮动态再结晶明显细化了奥氏体晶粒。原始奥氏体的晶粒取向决定了淬火后马氏体变体的类型,且淬火马氏体变体的组合方式均为密排面组合。不同变形量下淬火马氏体变体间的取向差集中在50°~60°范围内,可通过引入大角度晶界来细化晶粒。     

超高强度马氏体时效不锈钢中逆转变奥氏体的析出与长大行为

研究了一种Cr-Ni-Co-Mo系超高强度马氏体时效不锈钢中逆转变奥氏体的析出与长大行为。结果表明,经540℃×4 h时效后钢的强度达到峰值1940 MPa,并有薄膜状逆转变奥氏体沿马氏体板条界上非连续析出,使钢具有良好的综合力学性能。时效初期逆转变奥氏体在马氏体板条、板条界或原奥氏体晶界处形核,随着保温时间的延长,薄膜状的逆转变奥氏体通过与扩散有关的形核长大方式生长,最终形成块状,并与板条马氏体间保持着K-S或N-W关系。     

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.