Liangyun LAN
金属学报(英文版)
Thermomechanical process and tempering heat treatment were employed to produce the experimental steel plates. The effect of boron addition on the microstructure and mechanical properties of low carbon bainitic steels was studied in this paper. Microstructure observation and crystallographic features were conducted by using optical microscopy, SEM, TEM and electron back scattering diffraction (EBSD) analysis. The results showed that under the same rolling processes and heat treatment conditions, a substantial increase in strength is obtained by addition of boron into steel, but accompanied by an obvious drop in toughness. New martensite phase forms along the grain boundaries on tempering at 650 ℃ mainly due to boron segregation, which can further deteriorate impact toughness of the boron bearing steel. The EBSD analysis showed that high angle grain boundary is not responsible for the deteriorated toughness of the boron bearing steel because it has relatively higher percentage of high angle grain boundary than the boron free steel. The low toughness of the boron bearing steel is mainly attributed to the coarse boride precipitated particles according to the results of fractograph observation.
关键词:
Low carbon bainitic steel
刘建平
,
苗永霞
,
周晓湘
材料保护
doi:10.3969/j.issn.1001-1560.2005.08.007
为了减缓酸洗过程中金属制品的严重腐蚀,酸洗缓蚀剂被广泛使用,开发使用方便、低毒、低剂量、环保的酸洗缓蚀剂很有意义.利用失重法、动电位扫描法和电化学交流阻抗法对复配咪唑啉类缓蚀剂LAN的耐蚀性能进行了研究.结果表明:在50 ℃的5%(质量分数)盐酸中加入0.3% (质量分数)的LAN能有效地提高碳钢的耐蚀性能;LAN的缓蚀作用机理系几何覆盖效应,它在金属表面吸附成膜后,使阴极和阳极过程都受到了阻滞.同时,根据EIS谱提出了相应的特征等效电路.
关键词:
缓蚀剂
,
咪唑啉类
,
缓蚀效率
,
极化曲线
,
交流阻抗
,
等效电路
李彩荣
,
丁珊
,
罗丙红
,
文伟
,
周长忍
高分子材料科学与工程
在微波辐射作用下,以辛酸亚锡为催化剂,胆固醇为共引发剂引发L-丙交酯开环聚合制备了一组胆固醇-(L-乳酸)n低聚物(G-LAn),采用红外光谱、核磁共振氢谱、凝胶渗透色谱、差示扫描量热法、偏光显微镜和小角X射线衍射研究了产物的结构与性能.结果表明,C-LAn低聚物的相对分子质量可以通过改变n(胆固醇)∶n(L-丙交酯)值进行调控,其结构是由胆固醇端基和聚乳酸螺旋链构成的层状结构;C-LAn低聚物兼有结晶性和液晶性,且受低聚物分子中聚(L-乳酸)链段的长度影响,随着聚(L-乳酸)链段增长,低聚物呈现液晶态的温度区间变窄、温度升高.
关键词:
聚(L-乳酸)
,
胆固醇
,
微波合成
,
液晶
,
结晶
