[Discussion] Why is the ultrasonic flaw rating of plates and forgings inconsistent? In the GB / T 6402-2008 steel forgings ultrasonic testing method forging the ultra-straight probe quality grade is divided into 4, 4 the highest requirements. Single point discontinuous flat bottom hole equivalent diameter ≤ 3mm and GB / 72970-2004 thick steel plate in the ultrasonic testing method provides the quality of steel plate is divided into four levels, one level requirements.
The standard is not the same batch of people to develop, certainly have different ideas, and the most important feature of this standard is copied to the EN10228-3 / 4, the basic is directly followed 1, the more important large forgings surface quality requirements are higher, the general surface area Flaw detection requirements than the heart of a grade as much as the specific requirements, depending on the use of the situation, the surface generally require a higher φ2 or φ3 equivalent 2, steel do not know 3, unqualified generally can not be used, but also hard to say, once we do Over 2 products, a test failed, the first make do with the user, the user test pressure no problem, and then use for many years, another qualified qualified, when the pressure test did not pass, spray a person oil
