3 Fundamentals of press design

448 Solid forming (Forging)
Table 6.2.6: Surface qualities R z / R a achieved using different forging methods
forming process
hot e trusion
warm e trusion
warm cold e trusion
cold e trusion
ironing
upsetting
open die e trusion
5 12 15 18 20 30 40 50 60 70 80 90 100 0,5 1 2 3 4 6 8 10 12 15 20 25 30
before remo al of the lubricant carrier layer
after remo al of the lubricant carrier layer
are open die extrusion, ironing and solid forward extrusion. The surface
properties are influenced here by the following factors:
starting material: hot rolled, sand blasted, peeled, cold drawn
interface: sheared, sawn
intermediate annealing: scale free: under inert gas
with scale: sand blasted, pickled
Mechanical properties
The hardness, tensile strength and yield strength are increased by plastic
flow. However, at the same time the values for notch impact
strength, elongation and necking are decreased. Depending on the
degree of true strain, in the case of steels with low and medium carbon
content, tensile strength can increase by up to 120 %, yield strength by
between 100 and 300 %, and hardness by between 60 and 150 %.
Metal Forming Handbook / Schuler (c) Springer-Verlag Berlin Heidelberg 1998