T型不锈钢钎焊接头高温剥离失效机理研究

发布时间：2018-05-07 00:03

本文选题：T型钎焊接头 + 失效机理　；参考：《华东理工大学》2017年硕士论文

【摘要】：不锈钢板翅式换热器因其结构紧凑、换热效率高、制作成本低等优点,被广泛运用于核电领域中,换热器中的板翅结构采用钎焊技术制得,由于换热器长期服役于高温高压等苛刻环境下,加之钎缝处结构不连续、力学性能不匹配,裂纹易在钎缝处萌生并扩展,待裂纹扩展到临界尺寸,钎缝开裂致使换热设备失效瘫痪。然而当前对板翅结构钎缝的失效机理尚未明确,且缺少完整可靠的力学性能测试标准。因此对板翅结构钎焊接头高温力学性能及其失效机理的研究甚为重要。考虑到板翅式换热器钎焊接头失效形式类似于粘接剥离失效,本文采用剥离试验的方法,研究不同结构参数及试验参数下钎焊接头的剥离性能,并结合微观组织分析,探讨钎焊接头的剥离失效机理。主要研究内容如下:1)对T型钎焊接头进行高温剥离试验,得到钎焊接头的载荷位移曲线,获得最大剥离力、平均剥离力及断裂能等剥离性能特征参量。2)分析了母材厚度、钎缝间隙、加载速率及试验温度对T型钎焊接头剥离性能的影响,总结归纳了 T型钎焊接头剥离性能试验合理化试样结构尺寸范围及试验条件。3)借助扫描电镜及EDS能谱分析技术,分析了接头的元素分布情况,由此划分了钎焊接头特征区域,进一步探讨了不同结构参数及试验参数下钎焊接头剥离失效机理。
[Abstract]:Stainless steel plate-fin heat exchanger is widely used in nuclear power field because of its compact structure, high heat transfer efficiency and low manufacturing cost. Due to the long service of the heat exchanger in harsh environment such as high temperature and high pressure, in addition to the discontinuous structure of the brazing joint and the mismatch of the mechanical properties, the crack is easy to sprout and expand at the brazing joint, and the crack is to be extended to the critical size. The cracking of brazing joint resulted in the failure and paralysis of heat exchanger. However, the failure mechanism of brazed joints of plate-fin structure is not clear, and there is no complete and reliable test standard for mechanical properties. Therefore, it is very important to study the high temperature mechanical properties and failure mechanism of brazed joints of plate-fin structure. Considering that the failure mode of brazed joints in plate-fin heat exchangers is similar to that of adhesive debonding, the peeling properties of brazed joints under different structural parameters and test parameters are studied by means of peeling test, and the microstructure is analyzed. The delamination failure mechanism of brazed joints is discussed. The main research contents are as follows: (1) the peeling test of T-type brazed joint at high temperature is carried out, and the load-displacement curve of brazed joint is obtained, and the peeling characteristic parameters, such as maximum peeling force, average peeling force and fracture energy, are obtained, and the thickness of base metal is analyzed. The effects of brazing clearance, loading rate and test temperature on the peeling properties of T-type brazed joints, In this paper, the structure and dimension range and test conditions of T-type brazed joints are summarized. The distribution of elements in T-type brazed joints is analyzed by means of scanning electron microscope and EDS energy spectrum analysis technique, and the characteristic regions of brazed joints are divided. The delamination failure mechanism of brazed joints with different structure parameters and test parameters is discussed.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG407

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