磁粉检测设备及辅助器材对检测灵敏度的影响

摘  要

磁粉检测历史较久，并在世界范围内被广泛用于铁磁性材料的表面开口缺陷和近表面缺陷的检测。在传统磁粉检测中，当一个表面颜色较暗的工件需要做磁粉检测时，如未经打磨的焊缝、轧制的钢板，人们往往会在实施检测之前在被检表面施加一层白色的“漆”—反差增强剂，以增强磁粉显示与背景之间的反差，使缺陷容易被检测人员观察到。在检测大型工件时，人们又往往会选择触头式设备或磁轭式设备，因为这些设备轻便、灵活、对各类工件的适应性强。但很少有人知道反差增强剂是否会遮盖缺陷？施加的反差增强剂达到多厚才是合适的？触头式磁粉检测仪和磁轭式磁粉检测仪在检测灵敏度、尤其是检测深度上是否存在差异？在选择设备时该如考虑？本论文详细记录了在一系列带有人工或天然缺陷的试板上进行磁粉检测试验获得的结果。在各类检测条件都相同的情况下，比较研究了使用反差增强剂与不使用反差增强剂、不同反差增强剂厚度条件下、磁轭法和触头法之间在检测灵敏度上的差异，从而得出一个客观、科学的结论。

关键词：磁轭，触头，反差增强剂，磁粉检测，缺陷 

Abstract

Magnetic particle test is old and one of the most applied NDT techniques in the world for detecting defects which open to surface or are in subsurface of ferromagnetic material. In traditional magnetic particle test, when test being carried out on a part with dark surface such as not ground weld, rolled steel plate, people generally apply a layer of white “paint”, named contrast agent on the surface where will be tested before test to improve the contrast between indications and background, then make it easy to find the indicators might occur during test. When test being performed on a large part, people must choose prod equipments or yoke equipments for they being convenient, portable and suitable for various part. Whether the contrast agent might mask the defects? What thickness of the contrast agent is suitable? Is there any difference of sensitivity of detecting defects, especially subsurface defects, between prod equipment and yoke equipment? How to choose suitable equipment for a specific test? However, just a few people know it. The paper reported details the results obtained from a number of trials that were carried out on test plates that are with various natural or artificial defects. The differences of results between tests that are with contrast agent and that are not with contrast agent, between tests that are with different thickness of layer of contrast agent, between tests that are performed with prod equipment and that are performed with yoke equipment, have been investigated. And then we come to an objective, scientific conclusion.

Keywords: yoke，prod，contrast agent， Magnetic particle test，defects， 

目   录

1  引言 ……………………………………………………………………………………1

1.1  磁粉检测在现代工业中的应用 ………………………………………………………1

1.2  磁粉检测常用设备和器材的使用现状和相互比较 …………………………………1

1.3  课题的主要内容与步骤 ………………………………………………………………2

1.4  本课题的目的和意义 …………………………………………………………………3

2  磁粉检测的物理基础 ………………………………………………………………4

2.1  磁粉检测原理 …………………………………………………………………………4

2.2  磁痕与无缺陷部分的对比 ……………………………………………………………5

2.3  漏磁场 …………………………………………………………………………………5

3  磁粉检测用器材 ……………………………………………………………………10

3.1  仪器和辅助器材 ………………………………………………………………………10

3.2  试板 ……………………………………………………………………………………10

4  试验方法与步骤 ……………………………………………………………………17

4.1  反差增强剂对磁粉检测灵敏度影响的定性试验 ……………………………………17

4.2  反差增强剂对磁粉检测灵敏度影响的定量试验 ……………………………………18

4.3  反差增强剂施加厚度试验 ……………………………………………………………19

4.4  磁轭式探伤仪和触头式探伤仪在磁粉探伤性能试板上的对比试验 ………………19

4.5  磁轭式探伤仪和触头式探伤仪在模拟裂纹试板上的对比试验 ……………………22

4.6  磁轭式探伤仪和触头式探伤仪在模拟条形夹杂试板上的对比试验 ………………23

5  结论分析 …………………………………………………………………………… 26

参考文献 ………………………………………………………………………………… 27

致谢 ……………………………………………………………………………………… 28