预热及加热温度对三种高频电阻焊管焊缝组织和性能影响的研究

发布时间：2018-03-19 05:21

  本文选题：高频电阻焊　切入点：正火　出处：《燕山大学》2015年硕士论文　论文类型：学位论文

【摘要】：石油和天然气采用管道输送是最经济安全、环境友好的运输方式,为了满足应用过程对高频电阻焊管性能的严格要求,对焊缝处采用正火处理来改善其性能。本文设计了正火工艺的预热温度、峰值温度和保温时间三个不同参数,通过微观组织观察和性能分析,为确定最佳工艺提供实验依据。在Gleeble-3500热模拟试验机上进行热处理工艺的模拟,预热温度对各试验钢组织和性能的研究结果显示:不同预热温度对组织和性能的影响均较小,在比较平缓的变化趋势中,各试验钢在730℃预热时取得了韧性和强度的最佳配合。采用断口扫描、金相分析和疲劳性能测试、冲击试验等手段就峰值温度对试验钢的影响进行了研究,结果表明:三种试验钢随着峰值温度升高其组织与性能的变化趋势不尽相同。在峰值温度为950℃时,X52钢组织明显细化,晶粒大小均匀,弥散分布;L415钢大角度晶界百分数较高,铁素体晶粒等轴且大小均匀,珠光体含量较少。随着温度升高,这两种钢硬度与抗拉强度的变化趋势相同且与各自韧性变化相反,峰值温度为950℃时强度稍低,韧性较好,疲劳试验显示X52钢在950℃正火时疲劳寿命最长。X65钢在925℃正火时,铁素体晶粒细小均匀,珠光体含量较少且冲击功较高,断口的韧性特征明显,其强度的变化幅度较小。在生产实际中,根据钢种设定正火温度在925~950℃区间内能够有效改善组织,获得最佳的性能配合。根据生产实际,设定了在峰值温度进行保温的工艺,研究结果显示:X52钢经保温后晶粒粗化致韧性下降明显;X65钢的韧性以微弱幅度提升;L415钢组织细化,强度上升,韧性提高。
[Abstract]:Pipeline transportation of oil and natural gas is the most economical, safe and environmentally friendly mode of transportation. In order to meet the strict requirements for the performance of high-frequency resistance welded pipe in the application process, In this paper, the preheating temperature, peak temperature and holding time of normalizing process are designed. In order to provide the experimental basis for determining the best technology, the heat treatment process was simulated on Gleeble-3500 thermal simulator. The results of the study on the microstructure and properties of each test steel showed that the influence of different preheating temperature on the microstructure and properties was small. In the gentle trend, the best combination of toughness and strength was obtained when the test steel was preheated at 730 鈩，

本文编号：1632994