贝氏体等温温度对0.2C-1.5Si-2Mn-0.43Cu-0.26NiTRIP钢组织和性能的影响

应用CCT-AY-Ⅱ型钢板连续退火机、X射线衍射、扫描和透射电镜、EBSD和拉伸试验等研究了TRIP钢(0.2C-1.5Si-2Mn-0.43Cu-0.26Ni)贝氏体区(350~470℃)等温处理对组织和性能的影响。结果表明:在贝氏体等温温度为410℃时,TRIP钢综合力学性能最佳,抗拉强度达到1088 MPa,伸长率16.88%,强塑积18365 MPa·%。残留奥氏体在TRIP钢中存在的形态有粗大块状、薄膜状和细小粒状。其中薄膜状的残留奥氏体属于亚稳奥氏体,形变过程中发生渐进式转变,极大地发挥TRIP效应。残留奥氏体中的碳含量和薄膜厚度是决定残留奥氏体稳定性的关键因素。     

贝氏体区等温处理对超高强度TRIP钢组织的影

利用金相显微镜、EBSD技术、X射线衍射仪等研究了C-Si-Mn系冷轧TRIP钢贝氏体区等温处理对组织和力学性能的影响,并尝试利用间接方法控制TRIP钢中的相组成。结果表明,残余奥氏体直径在2~3μm之间,以椭圆状和细条状分布在铁素体晶界及晶内。随贝氏体区保温时间的延长,残余奥氏体体积分数先增大后减少,残余奥氏体中碳含量增多;随贝氏体区等温温度的升高,残余奥氏体体积分数达到峰值所需时间减少,峰值减小。相同等温时间下,等温温度越高,残余奥氏体中的碳含量越大。残余奥氏体的体积分数及其碳含量综合影响TRIP钢的力学性能。     

具有TRIP效应低屈强比贝氏体基超高强钢研究

对C-Si-Mn系TRIP钢采用等温退火工艺,得到具有TRIP效应贝氏体基高强钢。结果表明,TBF钢的组织主要由无碳化物贝氏体板条束、块状残余奥氏体、板条束间的薄膜状残余奥氏体及少量的回火马氏体组成。在连退过程中,贝氏体等温温度对TBF钢的组织和性能影响显著,当贝氏体等温温度为300℃时,TBF钢具有低屈服强度(789 MPa)、高抗拉强度(1241 MPa)以及良好的伸长率(16.6%)。等温300℃时,屈服强度的降低主要是因为80~190 nm的无碳化物贝氏体板条的生成。经过XRD测定,其残余奥氏体含量为12.04%,残奥含碳量经过测算为1.4%。稳定的块状残余奥氏体和无碳化物贝氏体板条有利于韧性的提高,相反,马氏体应该减少或避免。     

不同碳含量贝氏体合金钢等温淬火后的组织与性能

研究了3种碳含量(0.22C、0.34C、0.45C)的贝氏体钢在960℃奥氏体化+Ms点以上10～50℃等温淬火工艺下碳含量对贝氏体组织转变和力学性能的影响。结果表明,3种试验钢经过等温淬火处理后均获得由贝氏体铁素体和残留奥氏体相间分布组成的无碳化物贝氏体组织;随着碳含量的降低,贝氏体相变时间显著缩短,贝氏体铁素体板条变厚,硬度和抗拉强度呈下降趋势,但冲击性能显著提高,这主要是与低碳钢贝氏体转变温度更高,贝氏体铁素体板条粗大但高碳含量的大块状残留奥氏体减少有关。     

预相变马氏体对超级贝氏体钢组织热稳定性的影响

为明确超级贝氏体组织失稳机制以及探索提高超级贝氏体钢中残余奥氏体热稳定性的方法,通过预相变马氏体工艺,即在等温贝氏体相变前引入预相变马氏体,制备了中碳超级贝氏体钢。对比分析了回火前后中碳超级贝氏体钢显微组织和力学性能的变化,研究了预相变马氏体对中碳超级贝氏体钢中贝氏体组织及残余奥氏体热稳定性的影响。结果表明：预相变马氏体的存在能够细化贝氏体铁素体板条,提高残余奥氏体含量和热稳定性。预相变马氏体的引入及其对超级贝氏体组织的细化作用使得试验钢的屈服强度超过1 000 MPa,伸长率大于20%;300～600℃回火1 h后,高碳薄膜状残余奥氏体首先发生分解,形成细小的碳化物,然后贝氏体铁素体板条发生回复和再结晶,形成沿原板条方向的铁素体晶粒;600℃回火后试验钢的屈服强度仍与回火前相当,主要是预相变马氏体周围的薄膜状残余奥氏体未发生明显分解,能够抑制相邻贝氏体铁素体板条的回复。     

低温处理对3Cr2MoCoWV热作模具钢热疲劳性能的影响

通过比较低温处理前后3Cr2MoCoWV热作模具钢的热疲劳性能,结合透射电镜(TEM)分析低温处理对3Cr2MoCoWV钢热疲劳性能的影响。结果表明:贝氏体等温后,残余奥氏体呈薄膜状及块状两种分布形态。低温处理后,块状残余奥氏体完全转变为马氏体,贝氏体等温形成的残余奥氏体以更细小的膜状分布于贝氏体铁素体间。回火后,基体中超细小M2C型碳化物的弥散分布及少量未转变的残留奥氏体以薄膜状分布于贝氏体铁素体板条束间,提高材料的强度和韧性,阻碍了裂纹的萌生和扩展。低温处理得到材料的最佳强韧性配合,提高了3Cr2MoCoWV钢的热疲劳性能,其热疲劳损伤因子约是未经低温处理的一半。     

淬火配分贝氏体钢不同位置残余奥氏体C、Mn元素表征及其稳定性

采用部分奥氏体化-两相区保温-淬火-配分(IQPB)热处理工艺,借助SEM、TEM、XRD研究了淬火配分贝氏体钢组织形貌及残余奥氏体特征,利用EPMA、EBSD、纳米压痕等表征了不同位置残余奥氏体中合金元素的分布情况,结合室温拉伸应力-应变曲线,研究了C、Mn元素对不同位置残余奥氏体稳定性的影响及其相变规律。结果表明,淬火贝氏体钢室温组织中残余奥氏体以块状和薄膜状形态存在。在拉伸形变过程中,发生TRIP效应,残余奥氏体体积减小,相变优先发生在铁素体晶界,最后发生在贝氏体板条之间,C、Mn元素对残余奥氏体有稳定作用,使残余奥氏体不易发生相变。拉伸断口处应力集中,残余奥氏体完全转变为马氏体,距离断口2和4 mm处,残余奥氏体体积分数分别为3.12%和5.03%。薄膜状残余奥氏体比块状残余奥氏体稳定性更强,并且111γ晶向的残余奥氏体不稳定,容易向马氏体转变。     

低碳20Mn2SiVB钢贝氏体相变及其TRIP效应

用光学显微镜、扫描电子显微镜及X射线衍射仪对20Mn2SiVB钢在贝氏体区不同温度等温不同时间所获得的组织和形态进行了研究。试验表明,20Mn2SiVB钢在贝氏体等温转变时,首先在奥氏体晶界析出贝氏体铁素体,随着等温时间的延长,铁素体板条增多,分割奥氏体晶粒,形成贝氏体铁素体和其板条间的富碳奥氏体岛;在920 ℃奥氏体化,420 ℃贝氏体区等温不同时间后空冷所获得组织为：无碳化物贝氏体、粒状贝氏体、残留奥氏体和马氏体,各相的体积分数随着保温时间的不同有所变化。在920 ℃奥氏体化420 ℃等温5 min后,试样可获得较好的综合性能,具有一定的TRIP效应,其R_m≈ 1090 MPa;A。≈ 15.4%     

中碳低硅TRIP钢组织与力学性能的研究

采用Gieeble3500对中碳低硅TRIP钢进行了连续退火模拟,研究了不同两相区及贝氏体区等温温度对组织、力学性能及应变硬化规律的影响.结果表明,在780℃+ 400℃处理时获得最大的残余奥氏体量、伸长率及强塑积.450℃贝氏体等温时残余奥氏体转变量最大,由于残余奥氏体稳定较差,大量转变发生在变形早期阶段,其对伸长率的贡献不大.与之相反,400℃时残余奥氏体的力学稳定性较好,能较均匀且缓慢地发生转变,从而获得最好的塑性.     

热处理对高铝或硅TRIP钢组织性能的影响

鉴于1.0Si高Si型TRIP钢表面质量的恶化,本文设计了一种新型1.5Al高Al型TRIP钢。研究了退火温度和贝氏体区等温时间对两种钢力学性能的影响,并表征了1.5Al钢的微观组织。结果表明,随退火温度的升高,1.0Si和1.5Al试验钢的抗拉强度均先升高后降低,在840℃的退火温度下呈现抗拉强度的最高值;随贝氏体区等温时间的延长,1.0Si和1.5Al试验钢的抗拉强度均降低,而伸长率均逐渐提高,1.5Al试验钢的抗拉强度和伸长率均高于1.0Si钢; 1.5Al钢中的残留奥氏体存在两种形态,铁素体晶粒间的块状残留奥氏体,宽度在180 nm左右,贝氏体板条间的薄膜状残留奥氏体,宽度在80 nm左右。     

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.     

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.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.