S. Liu
,
D.Q. Yi
金属学报(英文版)
The La doped WC/Co powder was prepared by high energy ball milling. The changesof crystal structure, micrograph and defect of the powder were investigated by means ofXRD (X-ray diffraction), SEM (scanning electron microscope) and DTA (differentialthermal analysis). The results show that adding trace La element into carbides iseffective to minish the grain size of WC/Co powder. The La doped carbides powderwith grain size of 30nm can be obtained after 1Oh ball milling. The XRD peak of Cophase disappeared after 20h ball milling, which indicated solid solution (or secondarysolid solution) of Co phase in WC phase. The La doped powder with grain size of1Ohm is obtained after 30h ball milling. A peak of heat release at the temperatureof 470℃ was emerged in DTA curve within the range of heating temperature, whichshowed that the crystal structure relaxation of the powder appeared in the process ofhigh energy ball milling. After consolidated the La doped WC/Co alloy by high energyball milling exhibits ultra-fine grain Sizes and better mechanical properties.
关键词:
cemented carbide
,
null
,
null
,
null
S. Liu
,
Z.M. Yu
,
D.Q. Yi
金属学报(英文版)
Diamond films were deposited on the cemented carbide WC-15%Co substrates by a hot-filament chemical vapor deposition reactor. The substrate surfaces were chemically pretreated by the following two-step etching method: first using Murakami reagent for 1-3min, and second an HNO3:HCl=1:1 solution for 10-40min. It is indicated that the Co content of the substrate surfaces could be reduced from 15% to 0.81-6.04% within the etching depth of 5-10μm, the surface roughness of the substrates was increased up to Ra=1.0μm, and the substrates hardness was decreased from 89.0 HRA to 83.0HRA after the two-step etching. It is observed that the morphologies of the diamond films on the WC-15%Co substrates emerge in various shapes. The indentation testing shows that the good adhesion between diamond film and the substrate after HF CVD deposition could be obtained.
关键词:
chemical pretreatment
,
null
,
null
Zhaoyang ZENG
,
Lide ZHANG
,
Xiaohong YAN
材料科学技术（英文）
Ballistic transport of Q1D electrons through multiple magnetic barriers is investigated. It is shown that ballistic conductance peaks disappear progressively with the increase of the oscillation frequency of the confining parabolic potential.
关键词:
闵凡启
,
高立福
,
卢爱凤
,
王彦国
,
郭丽波
,
李国平
物理测试
doi:10.13228/j.boyuan.issn1001-0777.20150105
针对Q690D钢焊接后出现裂纹的现象,采用化学分析仪、金相显微镜、扫描电子显微镜对钢板的化学成分、金相组织、断口形貌及夹杂物等进行了系统的观察与分析.结果表明:材料的化学成分、金相组织、夹杂物等均在产品质量标准之内,焊接后出现裂纹的主要原因是焊接工艺不规范而导致的材料延迟性脆性开裂.为此制订了合理的焊接工艺规程,通过加强预热、焊后缓冷、优化焊接工艺参数、多道次焊接、焊后消氢处理等措施,有效地避免了焊接裂纹的出现.
关键词:
Q690D钢
,
焊接裂纹
,
延迟性脆性开裂
薛宪营
,
刘奉家
,
秦军
,
赵虎
钢铁
研究了Q345D低合金高强度中厚板冲击功、侧膨胀率和断面纤维率与温度之间的关系,并利用Boltzmann函数拟合法对不同厚度Q345D中厚板的韧脆转变温度进行了界定。结果表明：拟合所得到的韧脆转变温度各不相同,而且厚规格试样的韧脆转变温度低于薄规格试样的韧脆转变温度。经过优化Q345D连铸坯的连铸和控轧工艺,使Q345D低温韧性有了大幅度提高。
关键词:
Q345D
,
韧脆转变温度
,
Boltzmann函数
,
拟合
曹强
,
张清东
,
张晓峰
,
孙朝阳
材料科学与工艺
为建立准确的低碳马氏体钢淬火过程数值计算模型,采用Gleeble3500热模拟实验机对单轴应力作用下Q460D钢马氏体相变的相变塑性进行了研究.通过分析无应力循环和外加应力的实验过程,在试样径向膨胀曲线中分离出了相变塑性应变.实验结果表明,相变塑性应变随外加应力的增加而增大,相变塑性应变与施加应力大致呈线性关系.采用Greenwood-Johnson模型得到了Q460D钢的相变塑性系数.利用所得相变塑性系数计算出膨胀曲线,并与实测膨胀曲线进行比较,计算值与实验值吻合较好,文章结果可用于Q460D钢淬火过程的数值模拟.
关键词:
Q460D钢
,
马氏体相变
,
相变塑性
,
相变
,
变形
郭秀辉
钢铁研究
为保证莱钢Q275D热轧H型钢极限规格的-20℃冲击功值满足GB/T 700-2006要求,采用Nb微合金化结合再结晶控轧工艺试制了极限规格H400 mm× 200 mm×8 mm×13 mm的Q275D热轧H型钢.结果表明:试制产品的上屈服强度为360～368 MPa,抗拉强度为480～500 MPa,伸长率为32.5 ％～33.0％,平均冲击功为154～233 J,各项性能指标满足标准要求.
关键词:
热轧H型钢
,
再结晶控制轧制
,
Nb微合金化
赵鹏
,
乐可襄
物理测试
课题的目的就是针对Q690D钢拉伸试样分层成因进行系统地研究.采用扫描电镜及能谱分析等手段对Q690D钢分层缺陷进行了分析.结果表明:分层缺陷主要是由于铸坯中存在偏析处的铌、钛碳化物和硫化物、氧化物夹杂和带状组织引起的.通过对炼钢和轧钢生产过程的观察,提出了改进连铸和轧制工艺等相关措施,提出解决该问题的具体工艺措施并应用于实际生产.
关键词:
分层缺陷
,
Q690D钢
,
中厚板
赵鹏
,
乐可襄
物理测试
课题的目的就是针对Q690D钢拉伸试样分层成因进行系统地研究。采用扫描电镜及能谱分析等手段对Q690D钢分层缺陷进行了分析。结果表明：分层缺陷主要是由于铸坯中存在偏析处的铌、钛碳化物和硫化物、氧化物夹杂和带状组织引起的。通过对炼钢和轧钢生产过程的观察，提出了改进连铸和轧制工艺等相关措施，提出解决该问题的具体工艺措施并应用于实际生产。
关键词:
分层缺陷
,
Q690D steel
,
medium plate
