Forging DefectsS. Arvind Joshua Jaydev (20082203) Defects in Forging may Arise from: • Inherent Defects while forging • Faulty cuts in Forging Operations • Improper Heating and Cooling Dents 8. Laps/Folds 3.Types of Defects in Forging 1. Flow-through 6. Pitting 4. Distributed Metal Defects 7. Cracks 2. Coarse Grain Wrinkle 5. Void at Base of Rib 10. Underfilling 9. Push-through of Web under Rib . • External cracks are most dangerous • Cracks may appear at flash (if flash is too thin) • Internal cracks may develop during Upsetting . etc.1. Cracks • Excessive working of a surface at too low a temperature leads to cracks • Cracks may nucleate due to sulphur inclusions. The small inclusion appears to have initiated cleavage fracture. .Inclusions leading to cracking Cavity in the centre of a cleavage facet. “Upsetting” Forging . Flash . Combating cracks in Forging • Forging at increased temperature • Stress relieving before cutting off flash • Hot-cutting of Flash • Use concave die while upsetting. . • May be due to Too small die radius. excessive chilling of high friction .2. Laps/Folds • Also called “Fold-shut” • Occurs when two surfaces of a metal folds against each other without welding completely • Metal may flow past a die cavity that has already been filled. Example of Folding during Forging . Pitting .3. Pitting • Pitting occurs because of incomplete cleaning of Die • Die and workpiece should be free from scale while forging . 4. • These wrinkles fold into laps during forging. . Coarse grain Wrinkle • Wrinkling occurs during forging because the Billets contains coarse grains. 5. Flow-through . • Maybe avoided by increasing temp. of stock • Ensure lubricants are not trapped .Also… • Flow through may occur in cases where metal flows past the die recesses after filling. • Die impressions are hence not completely filled. 6. Distributed Metal Defects • Loose oxides minimized die-slug contact • Avoid too much lubricant . Dents .7. .Dents are caused by • Improper positioning of stock on die • Throwing around the forging while it is still hot. 8. Underfilling . Underfilling • Metal does not fill the recesses of the die completely • Because of loose scale and lubricant residue that accumulates in deep recesses of the die . this type of defect can be prevented . Rib and Web defects • A "peeling" lap forms in an aluminum rib-web forging as the corner of the die forces surface material ahead of the contact region.9. With a redesign of the upper die or preform. Dieter • http://www. E.References • “Mechanical Metallurgy”. G.com • Google Images .forgemag.