多级热处理对柔性立管用高强钢组织性能影响

通过对柔性立管用高强钢开展不同的热处理工艺实验并利用光学显微镜、扫描电镜、透射电镜和EBSD技术等表征手段研究了多级热处理对柔性立管用高强钢显微组织、力学性能以及抗氢致开裂性能的影响.结果表明:相对调质热处理而言，多级热处理能够显著细化组织，促使析出相细小弥散地分布于组织中并提高了组织中的晶界密度，从而使柔性立管用高强钢的强度升高.多级热处理大大提高了组织中氢陷阱的数量，减小了析出相的尺寸并改善了氢陷阱的分布状态，进而提高了实验钢的溶氢能力，从而在提高实验钢强度的同时明显改善了其抗氢致开裂性能.

Effect of Multi-stage Heat Treatment on Microstructure and Properties of High Strength Steel for Flexible Riser

The microstructure， mechanical properties and hydrogen-induced cracking resistance of high strength steel used for flexible riser after different heat treatments were studied by means of optical microscope(OM)， scanning electron microscope(SEM)， transmission electron microscope(TEM) and electron back-scattered diffraction(EBSD). The results show that compared with the traditional quenching and tempering treatment， multi-stage heat treatment can refine the microstructure， promote the dispersion of fine precipitates and increase the density of grain boundary so that the strength of the tested steel can be improved greatly. Moreover， since multi-stage heat treatment increases the number of hydrogen traps， reduces the size of precipitates and improves the distribution of hydrogen traps and the hydrogen solubility， the hydrogen-induced cracking resistance of the tested steel is also improved.