Ultrasonic flaw qualitative flow chart

一、according to processing technology analyze flaw property

Generated every kind of flaw Inside workpiece are related to processing technology 。Such as during welding process it maybe generate air hole、slag inclusion、incomplete fusion、lack of penetration and crack and so on flaws。

During casting it may generate air hole、shrinkage cavity、loose and crack and so on flaws。During forging it may generate samdwich 、fold、white spot and crack and so on flaws。Before flaw detection should refer to relevant blueprint and information of workpiece，knowing about material、structure 、geometric dimension and processing technology of workpiece,this is very useful for correctly judge estimate flaw property。

二、according to flaw features to analyze flaw property

Flaw property means the shape 、size、and density of flaw。

For plane flaw,detect on different direction ,its flaw echo altitude is obviously different，detect on the vertical direction,flaw echo is high;detect on the direction  that parallel to flaw , flaw echo is low,even no flaw echo,normal crack、interlayer、fold and so on flaw are belong to plane flaw。

For spot defect, detect on the different direction,flaw echo has no obvious change，normal air hole、slag inclusion are belong to spot flaw。

For intensive flaw,flaw wave is intensive and connected to each other，detect on different direction ,flaw echo has same condition, normal white spot、loose intensive air hole are belong to intensive flaw 。 

三、according to flaw waveform to analyze flaw property。

Inside flaw includes acoustic impedance has big effect on flaw echo altitude。White spot 、air hole and so on gas,acoustic impedance is very low reflected echo is high,nonmetal or metal slag inclusion has bigger acoustic impedance，reflected echo is low,otherwise,different types of flaw reflection wave has different shapes，such as air hole and slag inclusion、 air hole surface is smoother，interface reflectivity is high ,waveform steep is poignant。Slag inclusion surface is rough，interface reflectivity is low,simultaneously ,there is some acoustic wave penetrate slag inclusion,forming multiple reflection,waveform has big width with sawtooth。

It is easy to distinguish Single flaw and intensive flaw，normal single flaw echo is independent,but intensive flaw is clutter appear,and connected to each other。  All above are talking about still waveform。

四、 ultrasonic incident to different properties flaw,its dynamic waveform is also different。

The dynamic waveform with different properties intensive flaw  has different sensitivity on probe movement，white spot is very sensitive to probe movement,as long as probe move ,flaw wave instantly falls and rises,very active。But slag inclusion is not sensitive to probe movement,probe moving ,flaw wave changes slowly。  

五、according to bottom wave to analyze the properties of flaw

When there is flaw inside of workpiece,ultrasonic reflected by flaw and make acoustic energy decreased,bottom wave altitude decreases,and even disappeared。Different flaw with different properties,reflecting surface is different,,the altitude of bottom wave is not the same,so under some conditions can take advantage of bottom wave conditions to analyze flaw properties。

 When flaw wave is strong , bottom wave disappeared,can be thought as big area flaw ,such as slag inclusion , crack。

When flaw and bottom wave are exist together,can be thought as spot flaw or smaller area flaw。

When flaw wave is different height,bottom wave apparently decreased,can be thought as intensive flaw,such as white spot,loose,intensive air hole and slag inclusion

When flaw wave and bottom wave are low,or the two are disappeared,can be thought as bigger than inclined flaw or loose ,if appear “lin type” echo,can be thought as internal organization is big

Practical flaw detection usually according to experience and combined to processing technology of workpiece ,flaw features,、flaw wave and bottom condition to analyze flaw properties。