钛微合金化热轧高强钢奥氏体晶粒粗化行为

对钛微合金化热轧高强钢奥氏体晶粒粗化行为进行了实验研究。结果表明:当保温时间相同时,随着加热温度的升高,实验钢奥氏体平均晶粒尺寸呈现出先缓慢上升后迅速上升的趋势;当加热温度相同时,实验钢奥氏体平均晶粒尺寸随着等温时间的延长呈抛物线规律长大,1150℃加热奥氏体平均晶粒尺寸与保温时间的经验公式为:D1150℃=17.1 t0.2385,1250℃加热奥氏体平均晶粒尺寸与保温时间的经验公式为:D1250℃=29.9 t0.2916。综合考虑加热温度与保温时间对实验钢奥氏体晶粒尺寸的影响,并考虑微合金元素的溶解与析出规律,实验钢的加热温度定为1250℃左右,保温时间定为40 min较合适。     

60Mn3Al3Ni2CrVNb调质型低密度钢奥氏体晶粒长大行为

研究了60Mn3A13Ni2CrVNb调质型低密度钢的奥氏体晶粒长大行为,并分析了析出相对奥氏体晶粒长大行为的影响机理.结果 表明,在不同加热温度下(950～1250℃),随加热温度升高,实验钢的奥氏体晶粒逐渐增大,其中,1100℃以下加热时晶粒生长缓慢,1100℃及以上加热时,晶粒粗化明显,其晶粒粗化温度约为1100℃,此外存在1250℃加热时晶粒再次显著粗化现象.显微组织分析表明碳化铌是影响实验钢奥氏体晶粒长大行为的关键因素,且碳化铌的尺寸具有重要影响,实验钢中存在3种尺寸的碳化铌析出相,分别为小于50 nm、0.2～0.35 iμm、大于1μm.1100℃及以上加热时,尺寸小于50 nm的微小碳化铌析出相固溶,对奥氏体晶界的钉扎作用减弱,是1100℃及以上加热时晶粒粗化的主要原因;1250℃加热时,0.2～0.35 μm的碳化铌析出相固溶,导致1250℃加热时晶粒显著粗化;尺寸大于lμm的碳化铌析出相即使在1250℃保温12 h也难以溶解.     

核压力容器用SA508-4N钢的奥氏体晶粒长大行为

在10501250 ℃温度范围内,实测了核压力容器用SA508-4N钢在不同保温时间下的奥氏体晶粒尺寸,研究了SA508-4N钢的奥氏体晶粒长大行为。结果表明,随加热温度及保温时间的增加,SA508-4N钢的奥氏体晶粒尺寸长大,温度由1050 ℃上升到1250 ℃时,奥氏体晶粒尺寸呈指数增长;得到了SA508-4N钢加热过程中,奥氏体平均晶粒尺寸与保温时间关系的Beck方程;建立了奥氏体晶粒尺寸与加热温度和保温时间之间的Sellars模型,并验证了模型的准确性。     

40CrNi2MoE钢奥氏体晶粒长大的数学模型

利用金相实验方法,基于实验数据,应用Beck、Hillert、Sellars数学模型研究了40CrNi2MoE钢在加热温度850~1200℃和保温时间30~480 min下的奥氏体晶粒长大规律。结果表明,随加热温度升高和保温时间延长,40CrNi2MoE钢奥氏体晶粒逐渐长大,当加热温度超过1050℃或保温时间超过120 min时,试验钢奥氏体晶粒开始粗化。通过对Beck、Hillert和Sellars 3种晶粒长大数学模型对比分析,Sellars模型对40CrNi2MoE钢的奥氏体晶粒尺寸预测具有较高的精度,其奥氏体晶粒长大模型方程为:当温度为850℃≤T≤1050℃时,D5.49Sellars=7.64×1021texp(-390081/(RT));当温度为1050℃≤T≤1200℃时,D8.13Sellars=8.04×1041texp(-771322/(RT))。     

基于Matlab的300M钢奥氏体晶粒的长大规律

研究了300 M钢在不同加热温度(850～1180℃)和保温时间(5～120 min)下的奥氏体晶粒长大规律。绘制了300 M钢奥氏体晶粒尺寸在不同加热温度和保温时间下的等值线图;利用Sellars晶粒长大模型,构建了300 M钢的奥氏体晶粒长大数学模型。结果表明,300 M钢在高温加热时具有较好的抗晶粒粗化能力,在1050℃左右开始粗化。奥氏体晶粒尺寸等值线图可定性和定量预测奥氏体晶粒长大规律;奥氏体晶粒长大数学模型可用两个数学公式来描述,即当加热温度为850℃≤T≤1050℃时,d6.14=texp(68.97-64945.88/T);当加热温度为1050℃≤T≤1180℃时,d7.39=texp(134.56-144504.52/T)。     

X70管线钢在管件制造过程中晶粒长大规律研究

研究了X70级管线钢在不同加热温度和不同保温时间下的奥氏体晶粒长大规律。结果表明,当奥氏体化温度低于950℃时,试验钢有较小的晶粒尺寸;奥氏体化温度超过1 100℃,晶粒平均截距开始明显增大,一旦奥氏体化温度上升到1 300℃时,奥氏体晶粒已显著粗化。分析表明,试验钢奥氏体晶粒平均截距D!和奥氏体化温度T成指数关系。当奥氏体化温度为950℃和1 100℃时,奥氏体晶粒平均截距D!和保温时间t均成正比关系。研究结果对于X70级管线钢弯管和三通等管件制造的热加工过程有着重要参考价值。     

20CrMnTiH钢奥氏体晶粒长大规律及有限元模拟

通过金相实验,对20Cr Mn Ti H钢在不同加热温度(850~1150℃)及保温时间(10~40 min)下的晶粒长大规律进行了研究,基于所得数据,通过回归分析建立了适用于此种材料加热与保温过程的奥氏体晶粒长大模型,并将该模型引入有限元软件对奥氏体晶粒长大行为进行数值模拟。结果表明,奥氏体晶粒尺寸随加热温度升高而增大,且长大速度越来越快,随保温时间延长而增大,且长大速度不断减缓;1000℃为20Cr Mn Ti H钢的粗化温度,T≤1000℃时,晶粒长大缓慢,T≥1000℃时,晶粒急剧长大;有限元软件成功模拟了奥氏体晶粒长大过程,模拟结果与实验结果相符。     

S355J2微合金结构钢奥氏体晶粒长大的热模拟研究

通过热模拟和热处理试验研究了欧标S355J2微合金结构钢奥氏体晶粒的长大规律。热模拟焊接的试验结果表明,当峰值加热温度低于1250℃时,S355J2钢焊接热影响区(HAZ)奥氏体晶粒较细小,并随着保温时间的延长而不断长大;当峰值加热温度高于1250℃时,奥氏体晶粒急剧长大,长大幅度随着保温时间的延长而减小。热处理试验结果为,在低于1050℃加热时,S355J2钢奥氏体晶粒较细小,并且随着保温时间的延长奥氏体晶粒长大不明显;当加热温度高于1200℃时,奥氏体晶粒急剧长大,并且随着保温时间的延长长大幅度较大。     

非调质钢奥氏体晶粒长大行为研究

使用Gleebleb-1500热模拟试验机对F40MnV非调质钢在1000～1250℃进行等温保温试验,采用定量金相法计算了不同温度等温不同时间后的奥氏体晶粒尺寸。结果表明,1000℃及以下保温过程中,F40MnV钢奥氏体晶粒几乎不长大;在1000℃以上时,随着保温温度的升高和保温时间的延长,奥氏体晶粒长大显著。此外,拟合获得了F40MnV钢奥氏体晶粒的长大模型,所获得的模型可较为准确地预测奥氏体晶粒长大。     

基于热辗扩工艺的低碳钢环坯晶粒长大规律

低碳钢Q235是环件辗扩成形工艺的常用材料,辗扩前的加热规范对其辗扩过程及组织性能变化至关重要。利用箱式电阻炉在950~1200℃范围内,研究加热温度和保温时间对其加热过程中奥氏体晶粒长大规律的影响。借助于ZEISS显微镜观察分析其奥氏体晶粒长大组织,并采用截线法测定奥氏体晶粒平均直径。结果表明,随加热温度的升高和保温时间的延长,Q235钢奥氏体晶粒尺寸逐渐增大;且加热温度对奥氏体晶粒长大过程的影响要明显大于保温时间的影响,温度越高,晶粒生长指数越大;奥氏体晶粒的粗化温度为1100℃。在实验基础上,分别建立了Q235钢环坯在等温与非等温条件下晶粒长大动力学模型,并验证了等温长大模型预测结果与实验结果吻合良好。上述结果可为Q235环坯的辗扩成形提供准确的加热规范和奠定模型基础。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

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 Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

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.