文档介绍：Mechanical
Engineering Materials
(Bilingual Course)
Chapter Four
Contents
Plastic Deformation of Pure Metals
Plastic Deformation of Alloys
Microstructure and Properties
Changes During Plastic Deformation
Introduction
Plastic deformation is a permanent unrecoverable
deformation. When the load is removed, the material
will not return to its original shape.
轧制、拉拔、挤压、锻造、板料冲压
Plastic Deformation of Pure Metals
1. Plastic deformation of single crystals and
strain strengthening
Slip of single crystals
Slip is the displacement of a portion of a crystal relative
to another portion with the crystal structure of both
portions remaining unchanged.
滑移是晶体的一部分移动到另一部分的位置，并且
在移动过程两部分晶体的结构保持不变。
Plastic Deformation of Pure Metals
刚性滑移模型(Slip model of rigid)
Early materials studies led to the computation of the
theoretical strengths of perfect crystals, which were
many times greater than those actually measured.
Cu的临界切变应力为1540MN/m2， MN/m2
位错运动滑移模型(Slip model of dislocation)
滑移系(Slip System)
slip plane: Ordinarily there is a preferred plane, and in that plane
there are specific directions along which dislocation motion occurs.
slip direction: Slip will follows the direction of movement.
Slip system: The combination of the slip plane and the slip
direction.
For a particular crystal structure, the slip plane is the plane that
has the most dense atomic packing—that is, has the greatest
planar density. The slip direction corresponds to the direction,
in this plane, that is most closely packed with atoms—that is,
has the highest linear density.
滑移系(Slip System)
FCC
位错运动滑移模型(Slip model of dislocation)
For a single-crystal specimen
that is stressed in tension,
deformation will be as in
Figure, where slip