The raw materials used for forging carbon steel flanges are ingots, rolled products, extruded products and forgings. Rolling stock, extruding stock and forging stock are semi-finished products of carbon steel flanges processed by rolling, extruding and forging ingots respectively. In general, the appearance of internal defects or surface defects of ingots of carbon steel flanges is sometimes inevitable. Coupled with the improper forging process in the forging process of carbon steel flanges, the forgings eventually contain defects. The following briefly introduces some common defects in forgings.
Forging defects caused by defects in raw materials of carbon steel flanges usually include:
surface crack
Surface cracks often occur on rolled and forged bars of carbon steel flanges, generally in a straight shape, consistent with the main deformation direction of rolling or forging. There are many reasons for this defect, such as the subcutaneous bubbles in the ingot of carbon steel flange, which stretch along the deformation direction while exposed to the surface and develop deep inside during rolling. For another example, if the surface of the blank of carbon steel flange is scratched during rolling, it will cause stress concentration during cooling, which may crack along the scratch, etc. If this kind of crack is not removed before forging, it may expand during the forging of carbon steel flange and cause forging cracks.
Folding of carbon steel flanges
The reason for folding is that when the raw material of carbon steel flange is rolled, the groove sizing on the roll is incorrect, or the burr generated by the groove wear surface is involved during rolling, forming a crease with a certain angle with the material surface. For steel, there is iron oxide inclusion in the crease and decarburization around it. Folding, if not removed before forging, may cause folding or cracking of forgings.
