groove weld: a weld made in the groove between
two members to be joined
heat affected zone: that portion of the base material
which has not been melted, but whose mechanical
properties or microstructure have been altered by the
heat of welding, brazing, soldering, forming, or cutting
heat treatment: terms used to describe various types
and processes of heat treatment (sometimes called postweld
heat treatment) are defined as follows:
(a) annealing: heating to and holding at a suitable
temperature and then cooling at a suitable rate for such
purposes as: reducing hardness, improving machinability,
facilitating cold working, producing a desired microstructure,
or obtaining desired mechanical, physical, or
other properties
(b) normalizing: a process in which a ferrous metal
is heated to a suitable temperature above the transformation
range and is subsequently cooled in still air at
room temperature
(c) preheating: see preheating (separate term)
(d) quenching: rapid cooling of a heated metal
(e) recommended or required heat treatment: the
application of heat to a metal section subsequent to a
cutting, forming, or welding operation, as provided in
para. 331
(f) solution heat treatment: heating an alloy to a
suitable temperature, holding at that temperature long
enough to allow one or more constituents to enter into
solid solution, and then cooling rapidly enough to hold
the constituents in solution
(g) stress-relief: uniform heating of a structure or
portion thereof to a sufficient temperature to relieve
the major portion of the residual stresses, followed by
uniform cooling slowly enough to minimize development
of new residual stresses
(h) tempering: reheating a hardened metal to a temperature
below the transformation range to improve
toughness
328.3.2 Weld Backing Material. When backing
rings are used, they shall conform to the following.
(a) Ferrous Metal Backing Rings. These shall be of
weldable quality. Sulfur content shall not exceed 0.05%.
(b) If two abutting surfaces are to be welded to a
third member used as a backing ring and one or two
of the three members are ferritic and the other member
or members are austenitic, the satisfactory use of such
materials shall be demonstrated by welding procedure
qualified as required by para. 328.2.
Backing rings may be of the continuous machined
or split-band type. Some commonly used types are
shown in Fig. 328.3.2.
(c) Nonferrous and Nonmetallic Backing Rings.
Backing rings of nonferrous or nonmetallic material
may be used, provided the designer approves their use
and the welding procedure using them is qualified as
required by para. 328.2.
328.3.3 Consumable Inserts. Consumable inserts