This datasheet is compiled in good faith solely to assist others to evaluate the heat treatment techniques described.
Users do so entirely at their own risk. Neither CHTA nor the presenter is responsible for any consequences from any such
use. Datasheets shall not be used for contractual purposes neither directly nor by implication.
Contract Heat Treatment Association 1996
WHAT ARE THE TREATMENTS?
Stress relieving is applied to both ferrous and non-ferrous
alloys and is intended to remove internal residual stresses
generated by prior manufacturing processes such as
machining, cold rolling and welding. Without it,
subsequent processing may give rise to unacceptable
distortion and/or the material can suffer from service
problems such as stress corrosion cracking. The treat-
ment is not intended to produce significant changes in
material structures or mechanical properties, and is there-
fore normally restricted to relatively low temperatures.
Carbon steels and alloy steels can be given two forms of
(1) Treatment at typically 150-200°C relieves peak stress-
es after hardening without significantly reducing hardness
(e.g. case-hardened components, bearings, etc.):
(2) Treatment at typically 600-680°C (e.g. after welding,
machining etc.) provides virtually complete stress relief.
Non-ferrous alloys are stress relieved at a wide variety of
temperatures related to alloy type and condition. Alloys
that have been age-hardened are restricted to stress
relieving temperatures below the ageing temperature.
Austenitic stainless steels are stress relieved below
480°C or above 900°C, temperatures in between reducing
corrosion resistance in grades that are not stabilised or
low-carbon. Treatments above 900°C are often full
Applied to some, but not all, engineering steels,
normalising can soften, harden or stress relieve a
material, depending on its initial state. The objective of the
treatment is to counter the effects of prior processes, such
as casting, f