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P92钢管的生产旨在获得回火马氏体的微观组织;但在某些条件下,尤其在生产厚壁钢管时,可能会形成少量的铁素体.对此,本文对众多P92钢试样进行了大量深入的微观组织分析,并研究了回火马氏体基体中存在少量铁素体组织对其短期和持久性能的影响.发现P92钢管中可能存在成因和性能不同的2种铁素体组织;在钢液凝固过程中,如果铁素体和奥氏体形成元素未保持适当的平衡,稳定铁素体(也称δG铁素体)会形成并保留在冷却至室温后的微观组织中;在热处理过程中,如果从奥氏体化温度冷却的速度较慢,奥氏体会分解成铁素体和碳化物,形成另一种形式的铁素体;对不含铁素体和含铁素体体积分数为8%的试样进行对比分析,未观察到P92钢短期和持久性能上的明显变化,如进行了持续时间达70000h的蠕变性能试验,蠕变断裂数据处在基于ECCC评定数据曲线的分散带内.最后提出采用比较法测定无缝钢管和锻件中铁素体组织含量的指导方法,目前已经作为Vd TüV数据表,得到了确认和公布.
The production of P92 steel tube aims to obtain the microstructure of tempered martensite; however, under certain conditions, especially in the production of thick-wall steel pipe, a small amount of ferrite may be formed.In this paper, many P92 steel samples A great deal of in-depth microstructure analysis was carried out and the effect of a small amount of ferrite microstructure on the short-term and long-term performance of the tempered martensite was investigated. It is found that there are two kinds of ferrite In the process of solidification of molten steel, if ferrite and austenite-forming elements are not properly balanced, stable ferrite (also called δG ferrite) is formed and retained in the microstructure after cooling to room temperature ; In the heat treatment process, if the slow cooling from the austenitizing temperature, austenite will decompose into ferrite and carbide, to form another form of ferrite; for ferrite and containing Ferrite volume fraction of 8% of the samples for comparative analysis did not observe P92 steel short-term and lasting significant changes in performance, such as the duration of 70000h creep performance test, creep rupture data based on the ECCC Evaluation of the data distribution curve in the band. Finally proposed The guidance method for the determination of ferrite content in seamless steel tubes and forgings by the comparative method has now been confirmed and published as a Vd TüV data sheet.