Infiniti I30 (A33). Manual — part 151
PRECAUTIONS IN REPAIRING HIGH STRENGTH STEEL
29
Precautions in Repairing High Strength Steel (Cont’d)
Read the following precautions when repairing HSS:
1. Additional points to consider
The repair of reinforcements (such as side members)
by heating is not recommended since it may weaken
the component. When heating is unavoidable, do not
heat HSS parts above 550
o
C (1, 022
o
F)
Verify heating temperature with a thermometer.
(Crayon-type and other similar type thermometer are
available.)
When straightening body panels, use caution in
pulling any HSS panel. Because HSS is very strong,
pulling may cause deformation in adjacent portions
of the body. In this case, increase the number of
measuring points, and carefully pull the HSS panel.
When cutting HSS panels, avoid gas (torch) cutting
if possible. Instead, use a saw to avoid weakening
surrounding areas due to heat. If gas (torch) cutting
is unavoidable, allow a minimum margin of 50 mm
(1.97 in).
When welding HSS panels, use spot welding
whenever possible in order to minimize weakening
surrounding areas due to heat.
If spot welding is impossible, use M.I.G. welding. Do
not use gas (torch) welding because it is inferior in
welding strength.
PRECAUTIONS IN REPAIRING HIGH STRENGTH STEEL
30
10 (0.39) or over
12 (0.47) or over
18 (0.71) or over
20 (0.79) or over
27 (1.06) or over
31 (1.22) or over
The spot weld on HSS panels is harder than that of an
ordinary steel panel.
Therefore, when cutting spot welds on a HSS panel,
use a low speed high torque drill (1,000 to 1,200 rpm)
to increase drill bit durability and facilitate the operation.
SP150 HSS panels with a tensile strength of 785 to
981 N/mm
2
(80 to 100 kg/mm
2
, 114 to 142 klb/sq in),
used as reinforcement in the door guard beams, is too
strong to repair. When these HSS parts are damaged,
the outer panels also sustain substantial damage;
therefore, the assembly parts must be replaced.
2. Precautions in spot welding HSS
This work should be performed under standard working
conditions. Always note the following when spot welding
HSS:
The electrode tip diameter must be sized properly
according to the metal thickness.
The panel surfaces must fit flush to each other, leaving
no gaps.
Follow the specifications for the proper welding pitch.
0.6 (0.024)
0.8 (0.031)
1.0 (0.039)
1.2 (0.047)
1.6 (0.063)
1.8 (0.071)
Minimum pitch ( )
Thickness (t)
Precautions in Repairing High Strength Steel (Cont’d)
Unit:mm
REPLACEMENT OPERATIONS
31
Spot
weld
Description
The symbols used in this manual for cutting and welding / brazing operations are shown below.
Saw cut or air chisel cut
2-spot
welds
3-spot
welds
MIG plug weld
MIG seam weld/
Point weld
Brazing
Soldering
Sealing
2-spot welds
(2-panel overlapping portions)
3-spot welds
(3-panel overlapping portions)
REPLACEMENT OPERATIONS
32
Radiator Core Support
Service Joint
Indicates that there is an equivalent welding portion
with the same dimensions on the opposite side.
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