Effect of heat treatment temperature on dissimilar welded joint

The dissimilar metals 1Crl8Ni9 and 16MnR are welded by shielded metal arc welding process using electrode A312. The corrosion experiments are carried out on welded joint samples, which is as-welded and post-weld heat treatment at 650 ℃, 750 ℃ and 850 ℃, for 2 h in 70% sodium hydroxide solution. EDS and X-ray diffraction analysis are carried out on the samples after corrosion. Average corrosion rate calculation and microhardness measurement are conducted on both as- welded and post-weld heat treatment samples. The results indicate that average corrosion rate of as-welded joint metal is smaller than that of post-weld heat treatment joint metal. Compared with that of post-weld heat treatment at 750 ℃ and 850 ℃ for 2 h, the average corrosion rate of welded joint after post-weld heat treatment at 650 ℃ for 2 h increases greatly.     

用于文本校对的分词与词性标注一体化算法

分词和词性标注是中文处理中的一项基本步骤,其性能的好坏很大程度上影响了中文处理的效果.传统上人们使用基于词典的机械分词法,但是,在文本校对处理中的文本错误会恶化这种方法的结果,使之后的查错和纠错就建立在一个不正确的基础上.文中试探着寻找一种适用于文本校对处理的分词和词性标注算法.提出了全切分和一体化标注的思想.试验证明,该算法除了具有较高的正确率和召回率之外,还能够很好地抑制文本错误给分词和词性标注带来的影响.     

6061铝合金搅拌摩擦焊接头性能研究

采用搅拌摩擦焊对6 mm厚6061-T6铝合金板在不同工艺参数下进行焊接。观察了接头的显微组织,研究了接头室温拉伸性能及晶间腐蚀性能,测试了接头腐蚀前后的显微硬度。结果表明:在搅拌头转速900r/min、焊接速度100 mm/min、焊后缓冷工艺下,可得到性能较好的接头,其抗拉强度可达到母材的74%。接头显微硬度呈现"W"型分布,存在明显的软化区,母材的硬度最高,热影响区的硬度最低。晶间腐蚀最严重的部位发生在焊核区,经腐蚀后接头硬度显著下降。     

6061铝合金搅拌摩擦焊焊接接头应力腐蚀的敏感性

采用慢应变速率拉伸(SSRT)方法分析6 mm厚的6061-T6铝合金及其搅拌摩擦焊接头在模拟海水溶液及空气中的应力腐蚀敏感性,测试和分析搅拌摩擦焊接头金相组织、显微硬度和断口形貌。结果表明,焊核区晶粒细小,热机影响区晶粒出现弯曲及拉长变形,热影响区晶粒粗大。接头显微硬度值呈"W"型分布,其最大值为71.8 HV。在应变速率为1×10-6/s时,接头及母材在3.5%Na Cl溶液中具有应力腐蚀敏感性,接头应力腐蚀敏感性高于母材。