化学成分对电石锅用铸态耐热铸铁金相组织的影响

本文对某铸造公司高温时电石倒入电石锅后电石锅开裂的情况,进行研究。制备了含不同成分试验试件,发现不同化学成分含量的金相组织是明显不同的,进而得到对铸态耐热铸铁的使用性能影响。     

双辊薄带连铸低碳微合金钢的铸态组织

采用双辊薄带连铸技术制备了低碳微合金钢薄带,利用OM,SEM和TEM对铸态凝固组织、室温组织、析出及位错进行观察和分析.结果表明:低碳微合金钢铸带的凝固组织中二次枝晶间距约为12~15μm,相对于传统厚板坯和薄板坯连铸,铸带组织得到了明显细化.铸带的原奥氏体晶粒尺寸比较粗大,约为250~410μm,其组织由魏氏铁素体、珠光体和不规则铁素体组成.铸带组织中存在纳米级TiC析出和短棒状的渗碳体.TiC析出没有被薄带连铸的凝固过程及二次冷却过程明显抑制.铸带组织由于铸轧力及二次冷却速率不均匀导致大量位错的产生.     

金相组织自动识别技术的研究

对标准金相组织图像二值化，建立金相组织二值化标准图谱，将采集来的金相组织图像与金相组织二值化标准图谱进行图像匹配，自动识别采集来的金相组织图像显微组织。     

有色合金彩色金相技术的研究与应用

本文应用化学沉积着色法对铜、铝合金及双金属焊接接头的显微组织进行了上千次的着色试验，结果表明：彩色金相能够清晰地显示一般金相方法看不到的组织细节和特殊的相，其色彩鲜艳、分辩率高，给人们提供了很有意义的信息。同时还系统地介绍了化学沉积试剂的应用方法和试验操作技巧。     

等温淬火工艺对低碳球墨铸铁组织与性能的影响

对低碳球铁的等温淬火工艺进行了研究.测定了低碳球铁件在几种不同奥氏体化时间、等温时间下的力学性能,并对金相组织进行了分析.实验结果表明:在900℃奥氏体化40min,340℃进行30min的盐浴处理,能得到抗拉强度σb=1040Mpa,延伸率δ=3%,冲击韧性αk=42J/cm2,硬度HRC=32的较高的力学性能.     

半固态ZnAl27合金挤压成形金相组织研究

对常规ZnAl2 7合金和经机械搅拌得到的半固态ZnAl2 7合金材料进行了挤压成形试验 ,分析了合金在挤压成形后得到的试件的金相组织。结果表明 ,半固态ZnAl2 7合金挤压成形件的组织极为均匀细小。     

锌白铜合金材料的金相组织分析

该文对铸态和热挤压态锌白铜的金相组织进行分析,结果表明:铸态锌白铜合金材料的显徽组织由α相和β相组成,存在明显的枝晶.热挤压态锌白铜材料的显微组织中的α相呈长条状,并具有一定的方向性,这与热挤压过程中外力的作用有关.     

SiMnCr系高强度钢组织转变研究

对SiMnCr试验用钢，分别进行了淬火、等温淬火和空冷处理，并分别利用金相显微镜，扫描电子显微镜和透射电子显微镜进行了显微组织观察，测定了CCT曲线，淬火态下获得板条马氏体和其间的残余奥氏体薄膜组织，等温淬火得到贝氏体组织，锻造空冷状态下得到的以板条马氏体为主含贝氏体和少量位于板条间界的残余奥氏体薄膜复合组织，经300℃回火，无渗碳体析出。     

伪彩色增强技术在金相显微组织分析中的应用研究

将数字图像伪彩色增强技术应用于金相分析领域,建立了金属相灰度级~伪彩色映射关系的模型.设计了在计算机上运行的金相伪彩色系统,使输入的金相灰度图像中各相间微弱的灰度差转化为明显的色调差,显著提高了金相组织鉴别的衬度.     

GCr15轴承钢在电脉冲作用下的淬火和低温回火新工艺

本文研究GCr15轴承钢在脉冲电场的作用下淬火回火的新工艺,试验结果表明,在保证得到良好回火马氏体组织的同时,又使组织得到了细化,并降低了温度,又缩短加热和保温时间,是一种高效、低能、绿色环保的热处理新工艺。     

一种低碳多元微合金化结构钢的应用

石油机械重要零件用合金结构钢具有尺寸大、受力环境恶劣、受力形式复杂多样,要求大截面、厚壁零件采用材料具有较高淬透性并兼有优良的热处理工艺性能,以获得高而均匀的综合机械性能,提高其疲劳寿命,减少井下事故带来的巨大损失。利用低碳马氏体的特点以及多元微合金化提高淬透性,利用强韧化机理研发设计并成功生产应用的—相对于40Cr Mn Mo和4145H具有较高淬透性,一种低碳多元微合金化结构钢(高峰2号钢),其明显优势在于水淬不裂并具有更高的淬透性。     

低碳微合金钢回火过程的组织演变规律

采用膨胀实验和差式扫描量热实验,结合SEM、TEM和显微硬度测试,研究了低碳微合金钢700L在回火过程中的组织演变规律。结果表明,700L钢回火过程包括5个阶段:渗碳体I的析出(50～200℃)、残余奥氏体的分解(200～300℃)、渗碳体II的析出(250～400℃)、合金碳化物的析出(450～580℃)和Mn的分配(580～650℃)。在2℃/min的升温速率下,钢中渗碳体析出、合金碳化物析出及Mn分配三个阶段存在明显的硬度改变,而且合金碳化物析出阶段试样的体积改变最显著,这可能是影响钢中残余应力演变的重要阶段。     

一种微合金化马氏体不锈钢的连续冷却转变研究

用膨胀法结合金相与硬度分析研究了一种新型水轮机叶片用V、N微合金化CrNiMo不锈钢的连续冷却转变行为,获得了该钢的连续冷却转变(CCT)曲线及不同冷却条件下的显微组织和硬度。结果表明,试验用钢的1、3、和温度分别为580℃、730℃、295℃和190℃,其贝氏体和铁素体分别在冷速小于0.5和0.2℃/s时出现,冷速在0.056~0.5℃/s之间时,硬度随着冷速的增大迅速增加,尔后随着冷速的增大,硬度缓慢升高。     

Microstructural evolution and mechanical properties of a low-carbon quenching and partitioning steel after partial and full austenitization

In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron microscopy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austenitized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.     

Aging behavior of a copper-bearing high-strength low-carbon steel

The effects of aging temperature and time on the hardness and impact toughness of a copper-bearing high-strength low-carbon steel were investigated. The hardness of the aged samples reached maxima after 1 h and 5 h of aging at 500 and 450℃, respectively; this increase in hardness was followed by a decrease in hardness until a temperature of 700℃, at which secondary hardening was observed. The impact toughness of the aged steel was found to be higher for 5 h of aging. Transmission electron microscopy confirmed the presence of carbide and copper precipitates; also, the secondary hardening could be the result of the transformation of austenite (formed in the aging treatment) to martensite. Differential scanning calorimetry of the steel was performed to better understand the precipitation behavior. The results revealed that the precipitation of the steel exhibited two significant stages of copper precipitate nucleation and coarsening of the precipitates, with corresponding activation energies of 49 and 238 kJ·mol-1, respectively.     

超声无损表征30Mn2SiV钢复杂混合组织探讨

采用超声水浸线聚焦技术和频谱分析方法,研究了控轧控冷工艺生产的非调质D级抽油杆用钢30Mn2SiV复杂混合组织状态的超声无损表征方法,确定了不同质量分数的珠光体、铁素体及上贝氏体混合组织的相对衰减系数和相对相速度.含大量上贝氏体组织、珠光体 铁素体组织以及珠光体球化组织,相对衰减系数按照由大到小顺序变化,而相对相速度则依次增大.利用该方法可以无损区分30Mn2SiV钢的复杂混合组织.     

双相不锈钢与微合金钢异金属焊接接头的组织及性能

采用ER2209焊丝对双相不锈钢SAF2205与微合金管线钢X65进行熔化极气体保护焊接,获得了具有良好力学性能的异种钢焊接接头.焊接接头不同区域显微组织观察和成分分析表明,微合金钢与不锈钢焊缝间存在异金属熔合区和第二类边界线,熔合区存在Ni、Cr的浓度梯度分布,且硬度高于两侧的焊缝和母材.通过宏观拉伸、缺口拉伸和低温冲击实验测试了焊接接头的力学性能,并获得了接头不同部位在1mol.L-1NaCl溶液中的极化曲线.拉伸试样断裂发生于强度相对较低的微合金钢母材.焊缝金属的缺口拉伸强度和冲击韧性均略低于双相不锈钢母材,但腐蚀电位略高于母材.微合金钢热影响区与母材力学性能相当,腐蚀电位略高于母材.     

Effect of lower bainite/martensite/retained austenite triplex microstructure on the mechanical properties of a low-carbon steel with quenching and partitioning process

We present a study concerning Fe–0.176C–1.31Si–1.58Mn–0.26Al–0.3Cr (wt%) steel subjected to a quenching and partitioning (Q&P) process. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tensile tests demonstrate that the microstructures primarily consist of lath martensite, retained austenite, lower bainite (LB), and a small amount of tempered martensite; moreover, few twin austenite grains were observed. In the microstructure, three types of retained austenite with different sizes and morphologies were observed: blocky retained austenite (~300 nm in width), film-like retained austenite (80–120 nm in width), and ultra- fine film-like retained austenite (30–40 nm in width). Because of the effect of the retained austenite/martensite/LB triplex microstructure, the specimens prepared using different quenching temperatures exhibit high ultimate tensile strength and yield strength. Furthermore, the strength effect of LB can partially counteract the decreasing strength effect of martensite. The formation of LB substantially reduces the amount of retained austenite. Analyses of the retained austenite and the amount of blocky retained austenite indicated that the carbon content is critical to the total elongation of Q&P steel.     

Effects of heat treatment on the microstructures and mechanical properties of a new type of nitrogen-containing die steel

Nitrogen can increase the strength of steels without weakening the toughness and improve the corrosion resistance at the same time. Compared with conventional nitrogen-free die steels, a new type of nitrogen-containing die steel was developed with many superior properties, such as high strength, high hardness, and good toughness. This paper focused on the effects of heat treatment on the microstructures and mechanical properties of the new type of nitrogen-containing die steel, which were investigated by the optimized deformation process and heat treatment. Isothermal spheroidal annealing and high-temperature quenching as well as high-temperature tempering were applied in the experiment by means of an orthogonal method after the steel was multiply forged. The mechanical properties of nitrogen-containing die steel forgings are better than the standard of NADCA #207-2003.     

低碳微合金化含硼冷镦钢的冲击性能

通过对不同B含量的低碳硼钢和Nb、V微合金化低碳硼钢的冲击实验,研究了B含量及Nb、V微合金化对低碳硼钢冲击性能的影响. 结果表明:0.0006%～0.0015%的B将提高热处理状态钢的冲击韧性,B质量分数超过0.003%将降低钢的冲击韧性. Nb、V复合微合金化同时加入适量Al可显著提高热处理状态低碳硼钢的冲击韧性. Ti质量分数超过0.03%对低碳硼钢和微合金硼钢的冲击性能不利.