Aluminium Design and Construction John Dwight

Figure 6.8 Extent (CC) of nominal HAZ for thin plate.
6.5.2 Nominal HAZ
In performing resistance calculations for welded members, the accepted
practice is to use a nominal HAZ as an approximation to the true pattern
of softening. In this, a weakened region of uniform strength is assumed
adjacent to the weld, beyond which a step-change occurs to full parent
strength.
Figure 6.8 illustrates the nominal pattern for joints in thin plate, with
the step-change occurring at C, midway between the points A and B in
the true pattern. A similar principle applies to joints in thick plate, with
an assumed zone of uniform softening bounded by a line C (Figure 6.9).
6.5.3 One-inch rule
The one-inch rule was devised by Hill, Clark and Brungraber of Alcoa,
and has been widely used since the 1960s. It simply states that the
nominal HAZ extends a distance 1 inch (25 mm) in every direction
from an appropriate reference point in the weld. For an in-line butt, the
reference position is the centre-line of the weld (Figure 6.10(a)), while
for a fillet it is at the root (6.10(b)).
With fillet welds on thick plate, the one-inch rule officially allows the
HAZ boundary to be taken as an arc, as indicated in Figure 6.10(c). We
believe this to be an unnecessary refinement that negates the simplicity of
the rule, and instead would recommend the use of a square corner (as also
Figure 6.9 Extent of nominal HAZ (line C) for thick plate.
Copyright 1999 by Taylor & Francis Group. All Rights Reserved.