摘要
采用扫描电镜、电子背散射衍射技术和常规力学性能测试等手段研究了两种X70管线钢的显微组织和力学性能。结果表明:管线钢的低温韧性不仅与其有效晶粒尺寸有关,而且还与其组织中的马奥岛和析出相有关;但是,与管线钢中大角度晶界所占的百分比没有直接的关系。有效晶粒尺寸越小,马奥岛和富钛氮化物数量越少、尺寸越小,管线钢的低温韧性就越好。富铌碳化物与高密度的位错和亚结构不仅能提高管线钢的屈服强度,而且还能增大其加工硬化速率,从而使其抗拉强度明显升高,屈强比减小。由此可见,通过显微组织的优化,可以得到高强度高韧性的管线钢。
Microstructure and mechanical properties of two kinds of industrial X70 grade pipeline steels were studied by means of scanning electron microscopy( SEM),electron backscatter diffraction( EBSD) technique and mechanical properties testing. The results indicate that the low temperature toughness of the X70 pipeline steels depends not only on the effective grain size,but also on the other microstructural parameters,such as the MA constituents and precipitates. However,the property is independent on the fraction of high angle grain boundaries. The smaller the effective grain size is,the better the low temperature toughness is. The toughness of the steels increases with the decrease of the amounts of the MA constituents and Ti-rich nitrides,and the decreasing their sizes. In addition,the Nbrich carbides,substructures and high density of dislocations can increase the work hardening rate as well as the yield strength,which results in a high ultimate tensile strength and a low yield ratio. Therefore,for the pipeline steel,the excellent combination of properties can be obtained by optimizing design of the microstructure.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2015年第3期45-50,共6页
Transactions of Materials and Heat Treatment
基金
中国石油集团石油管工程技术研究院合作项目
关键词
X70管线钢
显微组织
力学性能
有效晶粒尺寸
针状铁素体
X70 pipeline steel
microstructure
mechanical property
effective grain size
acicular ferrite
