方管表麵缺陷的檢測方法，主要（yào）有以下五種：一電（diàn）渦流檢測.電渦流檢（jiǎn）測有多種形式，常用的有常規渦流檢測、遠場（chǎng）渦流檢測、多頻渦流檢（jiǎn）測（cè）和脈衝渦流檢測等（děng），利用電渦流傳（chuán）感器對金屬進行感應，方（fāng）管表麵不同缺陷類型和形狀將產生不同類型的（de）信號。其優點（diǎn）是檢測精度高、探測靈敏度高，檢測速度快，能檢測待檢測管材的表麵及亞表麵，且不受待檢測方（fāng）管表麵油汙等雜質的影響。缺點是易將非缺陷結（jié）構判定為缺陷，誤檢率較高，檢測分（fèn）辨率（lǜ）不容易調整。
There
are five main methods to detect the surface defects of square tubes: one is eddy
current testing. Eddy current testing has many forms, such as conventional eddy
current testing, far-field eddy current testing, multi-frequency eddy current
testing and pulse eddy current testing. Using eddy current sensors to induce
metal, different types and shapes of defects on square tubes surface will
produce different types of signals. It has the advantages of high detection
accuracy, high detection sensitivity, fast detection speed, can detect the
surface and sub-surface of the pipe to be tested, and is not affected by the
impurities such as oil contamination on the surface of the square pipe to be
tested. The disadvantage is that it is easy to judge the non-defective structure
as a defect, the false detection rate is high, and the detection resolution is
not easy to adjust. 二超聲波檢（jiǎn）測
Two-Ultrasound Detection
利用超聲波進入物體遇到缺陷（xiàn）時，一部分聲波會產（chǎn）生反射，發射和接收器可對（duì）反射波進行分析，就能異常精確地測出缺陷來。超聲（shēng）波檢測常用於鍛件檢測，檢測探傷靈敏度高，但是不易檢查形狀複雜的管材，要求被檢查的方管表麵有一定光潔度，並需有耦合劑充填滿探頭和被檢查表麵之間的（de）空隙。
When
ultrasound enters an object and encounters a defect, a part of the acoustic wave
will produce reflection. The transmitter and receiver can analyze the reflected
wave, and the defect can be detected abnormally and accurately. Ultrasound
detection is often used for forging detection, which has high detection
sensitivity, but it is not easy to inspect the pipe with complex shape. It
requires that the surface of the inspected square pipe should have a certain
degree of smoothness, and the coupling agent should be used to fill the gap
between the probe and the inspected surface.
三磁粉法檢測
Detection by three magnetic powder method
磁粉法（fǎ）檢測的原理是在方管（guǎn）材料（liào）中實現磁場，根據缺陷處的漏磁（cí）場與磁粉的相互作用，當表麵和近表麵有（yǒu）不連（lián）續或缺陷時，則在不連續處（chù）或缺（quē）陷（xiàn）處磁力線發生（shēng）局（jú）部畸（jī）變產生磁極。其（qí）優點（diǎn）是設備投資（zī）少，可靠（kào）性高，具有直觀性。缺點（diǎn）是操（cāo）作成本高，不能對缺陷準確分類，檢測速（sù）度較低。
The
principle of magnetic particle method is to realize magnetic field in square
tube material. According to the interaction between leakage magnetic field at
defect and magnetic particle, when there is discontinuity or defect on surface
or near surface, the magnetic line at discontinuity or defect will distort
locally to produce magnetic pole. Its advantages are less investment in
equipment, high reliability and intuition. The disadvantage is that the
operation cost is high, the defect can not be accurately classified, and the
detection speed is low.
四紅外線檢（jiǎn）測
Four Infrared Detection
通過（guò）高頻感應（yīng）線圈，在方管表麵產生感（gǎn）應電流，感應電流會導致缺陷區域消耗（hào）更多電（diàn）能，引起局部溫度升高，通過（guò）紅外線檢測局部溫度，從而（ér）確定（dìng）缺陷深度。紅外線檢測一般用於平直表麵的缺（quē）陷檢測，不（bú）適合檢測（cè）表麵（miàn）不平整金屬。
Through
high frequency induction coil, induction current is generated on the surface of
square tube. Induction current will cause more electric energy to be consumed in
defect area, causing local temperature to rise. The defect depth can be
determined by infrared detection of local temperature. Infrared detection is
generally used for flattening surface defect detection, not suitable for
detecting surface irregularity metal.
五漏磁（cí）檢（jiǎn）測
Five magnetic flux leakage detection
方（fāng）管的漏磁檢測方法和磁（cí）粉檢測方法（fǎ）非常相（xiàng）似，適用範（fàn）圍（wéi）、靈敏度和可靠性較磁（cí）粉（fěn）檢測方法（fǎ）更（gèng）強（qiáng）。
The magnetic flux leakage
testing method of square tube is very similar to that of magnetic powder testing
method, and its application scope, sensitivity and reliability are stronger than
that of magnetic powder testing method.
