Download - Defects in Forgings
Defects in forging
Mahander Pratap Singh(071577)Munish kumar(071425)
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What is forgingForging can be defined as the controlled plastic deformation of metals at elevated temperatures in to a predetermined size or shape using compressive forces exerted, through some type of die, by a hammer, a press or upsetting machine.
Forging enhances the mechanical properties of metals and improves the grain flow, which in turn increases the strength and toughness of the forged components.
Types of forging• Open die forging• Closed die forging
Forging Temperatures
Sr.No. Metal / Alloy
Forging Temperature oC
Starting Finishing
01Mild steel
1300 800
02Wrought iron
1275 900
03Medium carbon steel
1250 750
04High carbon steel
1150 825
05Copper, brass and bronze
950 600
06
Aluminium and magnesium
alloys500 350
DEFECTS IN FORGING
• Defective structure of metal; Reason – defective original metal.
• Presence of cold shuts or cracks at corners; Reason – improper forging and faulty die design.
• Incomplete component; Reason – less metal used, faulty die design and inadequate metal flow.
• Mismatched forging; Reason – die halves not properly aligned.
• Burnt and overheated metal; Reason – improper heating.• Fiber flow lines or grain flow lines disconnected; Reason –
very rapid plastic flow of metal.• Scale pits; Reason – formed by squeezing of scale into metal
during forging.• Oversize components; Reason – worn out dies, incorrect dies.
Types of defects (Samrat forging)
• Unfill • Mismatch• Cracks• Double strokes• Overheating• Lapping• Undersize
Quality measurements of products.
CRACKS• Causes: Surface cracking can occur as a result of excessive working of the s/c at too low
tempr.
Can be due to hot shortness.
• Remedial measures:
LAPPING• Causes: When metal flows past part of the die cavity that has already been filled or that is
only partly filled becoz the metal failed to fill in due to ssharp corner Due to excessicve chilling Due to high friction. Too small die radius .
• Remedial measures:
UNFILL• Causes:
• Remedial measures:
Cracking at flash• Causes: When the flash is thin.
• Remedial measures: Increase the flash thickness of the metal By relocating the flash to a less critical region of the forging.
PITTING• Causes:
• Remedial measures:
Out comes of the project
• Understand the whole process of forging.• Comes to understand various defects related to
forging process.• Tried to find the possible causes of defects at
samrat forging.• Tried to find out the possible remidial measures.