NNX-D64 21X10 21X11 ET 48 42 P.C.D 5X112 center hole 66.6 1piece forged wheel (custom 16-24inch and date) Is the Is Large forged   The white spots in large forgeds are extremely fine crispy cracks in the forging, round or oval silver white spots, ranging from several millimeters to tens of millimeters in diameter. According to the observation of the gold phase organization, no traces of plastic deformation were found near the white dot, so the white dot was crispy.   The existence of white dots on the forging parts not only leads to the sharp decline in mechanical properties, but also due to the existence of white dots, which can also lead to high stress concentration. It will cause parts to crack parts during thermal treatment and quenching, or suddenly break in parts in use, causing machine failure.   Therefore, white dots are a defect of forging. The technical conditions of large forging parts clearly stipulate that once the white dot is found, it must be scrapped. There are many theories about the formation of white spots. At present, the consistent point of view is that white spots are the result of the common action of hydrogen and internal stress (mainly structural stress) in steel. Without a certain amount of hydrogen and large internal stress, white spots cannot be formed.   During the cooling process after forging, as the temperature decreases, due to the transformation of the Auspace, in addition to the internal stress (mainly microstrip stress) in the forging, the solubility of hydrogen in steel will also be reduced. At this time, the internal stress will make the bit wrongly gather in the Asian Crystal Realm, forming a sub-micro-crack. When the hydrogen atom is relieved from the solid solution and precipitated into the sub-micro-crack, the hydrogen atom will be combined with hydrogen molecules in the crack to produce tremendous pressure. Therefore, in the local crispy of the hydrogen content in the steel, under the action of the stress and hydrogen output stress of the microstructure, the sub-display micro-cracks are continuously expanded or even cracking, resulting in extremely small internal cracks, thereby forming white spots.