Aluminium Design and Construction John Dwight

Table 6.2 HAZ-extent parameters for a single straight MIG weld
Rule P: A z is put equal to the relevant value in Table 6.2, namely
that which equation (6.6) would give when w=w 1 =8 mm.
Rule Q: Dimension s is taken equal to the appropriate value in Table
6.2 (proportional to the weld size).
3. Big welds (w 20 mm). The reasoning in this range is that each pass
has a ‘zone of influence’ as typically shown in Figure 6.12, which can
be related to Rosenthal’s three-dimensional heat-flow case (Figure
6.7). The radius s of this zone depends on the alloy type and the
level of thermal control. Table 6.2 gives proposed values of s
pessimistically based on a deposit size of 45 mm 2 per pass. The nominal
extent of the overall HAZ is constructed by taking the envelope of
the zones of influence for all the passes. This is achieved by drawing
a series of lines, as shown, each distant s from the relevant welded
surface, arcs being replaced by square corners.
Figure 6.12 Assumed extent of nominal HAZ at a large multi-pass weld, showing ‘zone of
influence’ for one of the passes.
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