30CrNi3MoV石油压裂泵高强钢组织结构及性能研究

发布时间：2018-01-19 13:17

  本文关键词： 电渣重熔 调质处理 组织结构 力学性能 电化学行为　出处：《安徽工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：目前30Cr Ni3MoV钢被广泛应用于石油行业,一般用于制造压裂泵、汽轮机等重要零件,然而石油开采难度越来越大,开采环境越来越恶劣,对石油机械用钢的性能要求也越来越高。本文首先对比电渣30CrNi3MoV钢和非电渣30CrNi3MoV钢的在不同工艺下的纯净度,并利用两次正火+调质处理的热处理工艺提高其力学性能,试图实现以非电渣锭代替电渣锭的目的,降低生产成本,减少对环境的污染;研究Mn、Si含量对非电渣30CrNi3MoV钢组织及性能的影响;利用极化曲线和电化学阻抗测试研究非电渣30CrNi3MoV钢在不同浓度HCl中的电化学腐蚀特征,利用金相显微镜、扫描电镜对非电渣30CrNi3MoV钢的组织及锈层形貌进行表征分析。研究结果表明:电渣重熔对30CrNi3MoV钢的纯净度的改善效果有限,电渣锭和非电渣锭中的S、P等杂质元素含量很低,电渣重熔对30CrNi3MoV钢中夹杂影响较小,两种钢中都只有少量(1级)的环状氧化物夹杂,未发现其他类型夹杂。两次正火工艺明显细化30CrNi3MoV钢的原奥氏体晶粒度,并改善其组织遗传现象。通过调质工艺后的电渣和非电渣重熔30CrNi3MoV钢的调质组织为回火索氏体,组织较细小。电渣钢横纵向晶粒都有轻微的晶粒大小不均匀现象。非电渣钢的强度略高于电渣钢,横纵向力学性能比都≥95%,两种钢的力学性能指标都达到了规定要求,在冶炼工艺合理的前提下,并通过两次正火+调质处理的热处理工艺后,以非电渣锭代替电渣锭是基本可行的。Mn含量从0.66%增加到1.05%时,对非电渣30CrNi3MoV钢的晶粒度、调质组织影响不大,Mn含量的提高减小了马氏体束尺寸,细化淬火组织,对试验钢的抗拉强度、屈服强度、伸长率、断面收缩率、硬度的影响很小,但会显著降低试验钢的冲击功,降低幅度为40%;Si含量从0.26%增加到0.7%对非电渣30CrNi3MoV钢的晶粒度级别没有影响,Si含量的提高降低了调质组织中碳化物的数量;增加了淬火组织中板条马氏体数目,减少了马氏体束以及针状马氏体数目;当Si含量增加时,试验钢的抗拉强度σb、屈服强度σ0.2、硬度HB分别提高了15.9%、13%、12%。在5%HCl溶液中,整个腐蚀过程受阳极反应控制,当Mn含量提高时,非电渣30CrNi3MoV钢的腐蚀电流密度Icorr增大,抗腐蚀性能下降,当Si含量提高时,试验钢的腐蚀电流密度Icorr降低,抗腐蚀性能提高。在10%HCl、15%HCl和20%HCl溶液中,阳极反应常数βa、腐蚀电流密度Icorr、锈层电阻Rr以及极化电阻Rs等参数的变化趋势与5%HCl溶液中的基本一致。随着HCl溶液浓度的增大,三种钢的抗腐蚀性能均下降,阳极反应常数βa和腐蚀电流密度Icorr增大,溶液电阻Rs也随之变小,试样的锈层厚度增大,当溶液浓度达到15%时,锈层厚度达到最大。当Mn含量增加时,失重量增加,失重的突变发生时间提前;当Si含量增加时,失重量减小,失重的突变发生时间推迟。
[Abstract]:At present, 30Cr Ni3MoV steel is widely used in petroleum industry, generally used to manufacture fracturing pump, steam turbine and other important parts. However, oil extraction is becoming more and more difficult, and the mining environment is getting worse and worse. The performance requirements of petroleum mechanical steel are more and more high. Firstly, the purity of electroslag 30CrNi3MoV steel and non-electroslag 30CrNi3MoV steel under different processes is compared. The heat treatment process of twice normalizing and tempering is used to improve its mechanical properties. The purpose of replacing electroslag ingots with non-electric slag ingots is attempted to reduce the production cost and to reduce the pollution to the environment. The effect of Mn-Si content on the microstructure and properties of non-electroslag 30CrNi3MoV steel was studied. The electrochemical corrosion characteristics of non-electroslag 30CrNi3MoV steel in different concentrations of HCl were studied by polarization curve and electrochemical impedance test. The microstructure and rust layer morphology of non-electroslag 30CrNi3MoV steel were characterized by SEM. The results showed that the effect of electroslag remelting on the purity of 30CrNi3MoV steel was limited. The content of impurity elements such as Schion P in electroslag ingot and non-electroslag ingot is very low. The influence of electroslag remelting on inclusions in 30CrNi3MoV steel is small, and there is only a small amount of ring oxide inclusions in both steels. No other inclusions were found. The original austenite grain size of 30CrNi3MoV steel was obviously refined by twice normalizing process. The microstructure of 30CrNi3MoV steel after quenching and tempering is tempered with Soxhlet. The microstructure is smaller and the grain size is slightly uneven in the transverse and longitudinal grains of the electroslag steel. The strength of the non-electroslag steel is slightly higher than that of the electroslag steel, and the ratio of transverse and longitudinal mechanical properties is 鈮，

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