©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
VIII for long
periods of time. The lowest welding current, which produces good fusion
with the base
metal, should be used to minimize heat input. Welding in one area for long
periods of time
should be avoided. A skip-welding technique should be used. This
means that each succeeding
pass should be made as far as possible from the preceding
pass. 8.1.5.5
Preheating should only be used when
the weldment has been exposed to tem- peratures
below 50°F or when the weldment is massive. Then preheat temperatures
of 100°F
should not be exceeded. Type
of Steel % Carbon
Preheat Temp.
F Type
of Steel % Carbon
Preheat Temp.
F PLAIN
CARBON STEELS NICKEL-CHROMIUM
STEELS Below 0.20
Up to 200 SAE
3115 0.15 200-400
0.20-0.30 200-300
SAE 3125 0.25
300-500 0.30-0.45
300-500 SAE
3130 0.30 400-700
0.45-0.80 500-800
SAE 3140
0.40 500-800
CARBON-MOLYBDENUM STEELS
SAE 3150 0.50
600-900 0.10-0.20
300-500 SAE
3215 0.15 300-500
0.20-0.30 400-600
SAE 3230 0.30
500-700 0.30-0.35
500-800 SAE
3240 0.40 700-1000
MANGANESE STEELS
SAE 3250 0.50
900-1100 Silicon
Structural 0.35 300-500
SAE 3315 0.15
500-700 Medium
Manganese 0.20-0.25 300-500
SAE 3325 0.25
900-1100 SAE
1330 0.30 400-600
SAE 3435 0.35
900-1100 SAE
1340 0.40 500-800
SAE 3450 0.50
900-1100 SAE
1350 0.50 600-900
LOW CHROMIUM-MOLYBDENUM STEELS
12% Manganese (Hadfield)*
1.25 Not Required
2.0% Cr, 0.5% Mo Up
to 0.15 400-600 HIGH
STRENGTH STEELS 2.0%
Cr, 0.5% Mo 0.15-0.25 500-800
Manganese-Molybdenum 0.20
300-500 2.0%
Cr, 1.0% Mo Up to 0.15 500-700
Chromium-Copper-Nickel 0.12
max. 200-400 2.0%
Cr, 1.0% Mo 0.15-0.25 600-800
Chromium-Manganese 0.40
400-600 MEDIUM
CHROMIUM-MOLYBDENUM STEELS NICKEL
STEELS 5.0% Cr, 0.5%
Mo Up to 0.15 500-800
SAE 2015 0.10-0.20
Up to 300 5.0%
Cr, 0.5% Mo 0.15-0.25 600-900
SAE 2115 0.10-0.20
200-300 8.0%
Cr, 1.0% Mo 0.15 max. 600-900
Nickel Steel 0.10-0.20
200-400 STAINLESS
CHROMIUM STEELS SAE
2315 0.15 200-500
Type 410 300-500
300-500 SAE
2320 0.20 200-500
Type 430 300-500
300-500 SAE
2330 0.30 300-600
Type 446 300-500
300-500 SAE
2340 0.40 400-700
STAINLESS CHROMIUM-NICKEL STEELS
MOLYBDENUM STEELS
18-8 Type 304 0.07
SAE 4140 0.40
600-800 25-12
Type 309 0.07 Usually
do SAE 4340
0.40 700-900
25-20 Type 310 0.1
not require SAE
4615 0.15 400-600
18-8 Columbium preheat
but SAE 4630
0.30 500-700
Type
347* 0.07 it
may be SAE 4640
0.40 600-800
18-8 Molybdenum desirable
to SAE 4820
0.20 600-800
Type
316* 0.07 heat
to 32 F 18-8 Molybdenum
Type
317 0.07 RECOMMENDED
PREHEAT TEMPERATURES FIGURE
7 * When ambient
temperature is below 50°F, preheat to 100°F. Interpass
temperatures over 500°F should be avoided.
