高压锅炉无缝钢管用P91管坯组织及性能研究

本课题对P91管坯试样的低倍、夹杂、显微组织、热压缩变形行为以及常温力学性能进行了分析研究。结果表明:采用"电炉+炉外精炼+真空脱气冶炼"工艺,可制备钢质纯净、夹杂物级别较低的P91管坯;P91具有良好的淬透性,在空冷条件下,即可获得马氏体组织;P91经高温正火和回火热处理后,组织为晶粒细小的亚晶化回火马氏体组织;在同一应变速率条件下,变形抗力对变形温度比较敏感,采用较高的变形温度,可降低锻造过程中的变形抗力,当变形温度达到1 150℃以上时,随着变形程度的增大会发生奥氏体组织的动态再结晶,从而进一步细化晶粒;P91管坯试样的常温力学性能可满足GB5310以及ASME SA335标准要求。

Study on Microstructure and Properties of P91 in High-pressure Boiler Seamless Steel Pipe

The macroscopical structure and inclusions and microstructure and hot compression deformation behavior and mechanical properties at room temperature for the specimen of P01 pipe billet were analyzed and studied. The results showed that the I）91 pipe billet with pure steel and lower level inclusions could be made by using EBT＋LF＋VD process; the P91 had a good hardenability, the martensite microstructureyou could be got in the air-cooled condition; by using the high temperature normalizing and tempering heat treatment, the microstructure of P01 became subgrain tempered martensite with finer grains; at the condition of the same strain rate, the deformation resistance was more sensitive to deformation temperature, high deformationtemperature reduced the deformation resistance during the forging process, when the deformation temperature was above 1 150 ~C, austenite occurred dynamic recrystallization with the degree of deformation increasing, the grain was further refined; the mechanical properties of PO pipebille specimens at roomtemperature could meet the requirements of GB5310 and ASME SA335 standards.