Forgeability of Metals

Forgeability is a Combination of the Following Characteristics

  • The flow stress
  • The ability to fill a die
  • he degree of deformation that can be carried out without failure (due to surface or internal cracking)

Although in general the forgeability of metals increases with increasing temperature, for certain metals there is a maximum temperature above which some undesirable phenomena occur, such as fast grain growth or melting of a phase.

Fine grain metals have better forgeability. Metals with insoluble inclusions tend to be brittle and have low forgeability.

Two popular tests for determining the forgeability of materials are the ‘upset test’ (where cylindrical specimens are upset in steps until they start cracking radially or circumferentially) and the hot ‘twist test’ where a round bar is heated in a tubular furnace then twisted. The number of twist turns to failure is a relative measure of forgeability. Testing can be carried out in a range of temperatures and strain rates to determine the best conditions for practical forging.

The table below ranks metals / alloys in order of decreasing forgeability and approximate hot forging temperature range

Aluminium alloys
400 – 550
Magnesium alloys
250 – 350
Copper alloys
600 – 900
Carbon and alloys steels
850 – 1150
Martensitic stainless steels
1100 – 1250
Maraging steels
1100 – 1250
Austenitic stainless steels
1100 – 1250
Nickel alloys
1000 – 1150
Semi-austenitic PH stainless steels
700 – 900
Titanium alloys
1050 – 1250
Iron – base supera alloys
1180 – 1250
Cobalt – base super alloys
1180 – 1250
Columbium alloys
1050 – 1350
Tantalum alloys
1150 – 1350
Molybdenum alloys
1050 – 1200
Nickel base super alloys
1050 – 1200
Tungsten alloys
1200 – 1300
Beryllium
1220 – 1550