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News & Knowledge

Crack inspection of induction quenching parts


There are mainly several methods for crack inspection of High frequency induction heating machine quenching parts:


1) By macroscopic observation or inspection with a magnifying glass, only large quenching cracks can be found.


2) The quenching workpiece is immersed in kerosene, wiped clean with cotton yarn, and then the surface is sandblasted, small quenching cracks can be found.


3) Stain detection.The mechanism is to spray or brush the characteristic dye with strong capillary action to the surface where the cracks need to be inspected and impregnate it for more than 15min. Then remove the excess dye with distilled water, blot it dry, and then apply the concentrated slurry of kotzen soil and dry it. The cracks can be exposed.


Now there is a standard color flaw detection agent product supply, commonly used general color agent set has three kinds of spray, namely cleaning agent, osmotic agent and developing agent.The operation method is as follows: (1) first clean the oil on the specimen surface;(2) use a brush or injector to apply the permeate on the specimen to be tested, and keep it moist for 10-15min;Remove the permeable liquid on the specimen surface with washing liquid;(4) spray developing liquid, after the drying of the developing liquid in the test surface to form a layer of film, there are cracks in the film color, according to the coloring of the situation can determine the shape of the defect.


4)Mmagnetic particle inspection.A better method is fluorescence inspection, can find the very fine quenching crack.


5) Under a metallographic microscope, cracks in the sample section can be observed.Its shape is generally head thick tail thin, that is, the quenching surface crack wide, the more to the heart of the extension of the more fine.Microscopic cracks can also occur at the junction between the hardened layer and the heart.