回火次数对P91焊管接头力学性能的影响

发布时间：2018-05-13 11:02

本文选题：无缝管 + 焊接接头　；参考：《工程科学学报》2017年04期

【摘要】：采用光学显微镜、X射线衍射分析、透射电镜、选区电子衍射及常温与高温拉伸试验等检测手段,基于不同回火次数下P91焊接接头显微组织的演化过程研究其对力学性能的影响.结果表明,随着回火次数的增多,接头显微组织主要保留了板条马氏体位向的回火索氏体,主要相为α-Fe相和Fe-Cr相,热影响区的室温及高温强度先增大后减小.在回火一次时,弥散析出的MX(M=V/Nb,X=C/N)型碳氮化物、位错缠结及亚稳态的位错网对接头有一定的析出强化及位错强化作用,其力学性能较佳,高温抗拉强度达最大值232.66 MPa;随着回火次数进一步增多,离散分布的碳化物Cr23C6逐渐偏聚并在晶界处演化为串链状分布,使晶界脆化,强度降低,但韧性有所改善.
[Abstract]:By means of optical microscope X-ray diffraction, transmission electron microscope, selective electron diffraction and tensile test at room temperature and high temperature, the effect of microstructure on mechanical properties of P91 welded joints was studied based on the evolution process of microstructure of P91 welded joints under different tempering times. The results show that with the increase of tempering times, the microstructure of the joints is mainly tempered with lath martensite, the main phases are 伪 -Fe phase and Fe-Cr phase, and the strength of the heat affected zone increases first at room temperature and then decreases at high temperature. During tempering, the diffusion-precipitated MXX / V / NbPX / C / N, dislocation entanglement and metastable dislocation net have a certain precipitation strengthening and dislocation strengthening effect on the joints, and their mechanical properties are better. The tensile strength at high temperature reaches the maximum value of 232.66 MPa, and with the further increase of tempering times, the dispersed carbide Cr23C6 gradually segregates and evolves into a chain distribution at grain boundaries, which makes the grain boundary embrittlement, the strength decreases, but the toughness is improved.
【作者单位】：西安建筑科技大学冶金工程学院;陕西省冶金工程技术研究中心;陕西省锅炉压力容器检验所;
【基金】：国家质检总局科技计划资助项目(SNQTS_2013QK148)
【分类号】：TG407;TG156.5

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