材料期刊网

灰铸铁激光处理层内的残余奥氏体及应变诱发马氏体

李成劳 , 沈莲

金属学报

本文用X射线衍射仪测定了激光处理灰铸铁硬化层内的残余奥氏体分布以及磨损过程中残余奥氏体量的变化;对硬化层磨面表层金属薄膜进行了电子显微镜观察。结果表明,硬化层中的残余奥氏休在1.72MPa载荷下的滑动磨损过程中,应变诱发出两种形态的马氏体,应变诱发马氏体对滑动磨损抗力有利。

关键词: 激光表面改性 , gray cast iron , residual austenite , martensite , wear resistance

激光熔化处理对灰铸铁显微组织的影响

沈莲 , 李成劳 , 王秀苓 , 马丽华 , 朱道珍

金属学报

本文借助光学显微镜,透射电镜和扫描电镜,分析了HT20-40灰铸铁于激光熔化处理后表面显微组织特征,并探讨其形成原因。

关键词: 激光处理 , gray cast iron , microstructure

EFFECT OF NITROGEN ON GRAPHITE MORPHOLOGY IN GRAY CAST IRON

ZHAI Qijie , HU Hanqi University of Science and Technology Beijing , Beijing , China Faculty of Foundry , University of Science and Technology Beijing , Beijing 100083 , China

金属学报(英文版)

The distribution of N and morphology of graphite in gray cast iron containing N were studicd by adopting the man-made specimens of Fe-C-Si-Mn alloys with some N added. The N adsorbed along the interfaces between graphite and matrix together with solid- solutioned in graphite is believed to be the principal cause of morpholongical variation of graphite.

关键词: gray cast iron , null , null

SOLUBILITY OF NITROGEN IN MOLTEN GRAY CAST IRON

ZHAI Qijie , HU Hanqi , University of Science and Technology Beijing , Beijing , China HU Hanqi , Professor , Faculty of Foundry , University of Science and Technology Beijing , Beijing 100083 , China

金属学报(英文版)

The expressions of the dependence of nitrogen solubility in molten gray cast iron on the temperature and composition of the melt were proposed under the condition of foundry practice. Three gray cast iron specimens with different compositions were examined in good agreement with the derived expression.

关键词: gray cast iron , null , null

RESIDUAL AUSTENITE AND STRAIN-INDUCED MARTENSITE IN LASER HARDENING LAYER ON GRAY IRON

LI Chenglao SHEN Lian Xi'an Jiaotong University , Xi'an , China LI Chenglao Lecturer Dept.of Material Engineering , Xi'an Jiaotong University , Xi'an 710049 , China

金属学报(英文版)

The distribution of residual austenite in the laser hardening laver on the gray cast iron and the change in the amount of residual austenite during sliding wearing have been investigated by X-ray diffractometer.The thin foils of the hardening layer worn down have been observed by electron microscopy.It was revealed that two types of martensite are strain-induced by slid- ing wearing under load of 1.72 MPa on the hardening layer of residual austenite.The strain induced martensite is profitable to improve the sliding wearing resistance.

关键词: laser surface modification , null , null , null , null

EFFECT OF NITROGEN ON MATRIX STRUCTURE OF GRAY CAST IRON

ZHAI Qijie HU Hanqi University of Science and Technology Beijing , China associate professor , Faculty of Foundry , University of Science and Technology Beijing , Beijing 100083 , China

金属学报(英文版)

Effect of nitrogen on matrix structure of 3 different varieties of gray cast iron,i.e., sub-eutectic Fe-C-Si,near-eutectic Fe-C-Si and Fe-C-Si-Mn,has been investigated. The eutectie colony structure of gray cast iron may be refined,the pearlite content increased and the micro-hardness of pearlite and ferrite raised with an addition of nitrogen.The influ- ence of nitrogen on the transformation temperature of the equilibrium and non-equilibrium phases,as well as,the solution of nitrogen in ferrite and cementite seem to be the major rea- sons to strengthening the matrix structure of gray cast iron.

关键词: nitrogen , null , null , null , null

Analysis of Laser Surface Hardened Layers of Automobile Engine Cylinder Liner

钢铁研究学报(英文版)

关键词:

预热温度对灰铸铁表面激光熔覆镍基涂层组织与性能的影响

闫世兴 , 董世运 , 徐滨士 , 王玉江 , 任维彬 , 方金祥

材料工程 doi:10.11868/j.issn.1001-4381.2015.01.006

采用CO2激光器在HT250基体上分别以不同预热温度制备NiCuFeBSi合金熔覆层,研究基体预热温度对白口组织控制、结合界面元素分布及抗拉强度的影响.结果表明:提高预热温度,有利于降低半熔化区白口化趋势,白口组织呈断续分布,但也导致熔覆层稀释率增大,更多基体Si,P杂质元素稀释进入熔池形成杂质相.拉伸实验表明:熔覆层抗拉强度远大于HT250,熔覆层断裂机制为解理与准解理混合型断裂.观察发现NiCuFeBSi合金激光熔覆层凝固后晶粒内部存在大量位错线并交叉缠结形成亚结构,进一步细化了晶粒,有利于提高熔覆层的强度与性能.最终获得NiCuFeBSi合金熔覆层在HT250基体上的最佳温度为室温30℃.

关键词: 激光熔覆 , 灰铸铁 , 预热温度 , 白口组织 , 抗拉强度

Gray Cast Iron With Directional Graphite Flakes Produced by Cylinder Covered Compression Process

钢铁研究学报(英文版)

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灰铸铁HT250的低周疲劳行为

袁永立 , 何国球 , 樊康乐 , 佘萌 , 卢棋 , 刘晓山 , 朱旻昊

材料热处理学报

研究了取样于汽车发动机缸体上的HT250灰铸铁的常温低周疲劳行为.对循环应力-应变和应变-疲劳寿命数据进行了分析,给出了该材料在常温下的疲劳参数.循环应力响应行为表明,HT250灰铸铁在较小应变幅下经历初期循环硬化、循环软化、断裂;而较大应变幅下几乎无硬化阶段,循环软化至断裂,原因在于循环形变过程中位错之间以及位错与石墨、夹杂物之间的相互作用.疲劳断口分析表明:疲劳裂纹萌生于片状石墨尖端,夹杂物及局部软点,且沿石墨扩展;疲劳断裂的方式是准解理脆断和沿晶断裂的复合机制,断口有解理面和二次裂纹,并存在韧性断裂特征;断口附近的气孔、夹杂等铸造缺陷较多,部分石墨片互相连接成网状,导致局部区域强度降低,促进失效.

关键词: HT250灰铸铁 , 低周疲劳 , 循环应力响应 , 疲劳裂纹