FerriteFerrite is a body-centered cubic form of iron in which
some carbon is dissolved.
Metallurgical Changes during welding
Influence of Alloying Elements on the Hardenability of Steel
Broad Catagories of Steel
Type of SteelCarbon ContentAlloy Content1. Low Carbon<
0.25%No Alloy except Mn up to 1.65%2. Medium Carbon0.25 to
0.55%< 5.0%3. High Carbon> 0.55%> 5.0%
Weldability Index
Thermal Severity Number
Weldability Index
Minimum preheat temperature 0C for welding with electrode size
in mm
3.2
4.0
5.0
T.S.N 2
D
0
E
50
0
F
125
25
T.S.N 3
C
0
D
75
0
E
100
25
0
F
150
100
25
T.S.N 4
C
50
D
100
25
E
125
75
0
F
175
125
75
T.S.N 6
B
50
C
100
25
D
150
100
25
E
175
125
75
F
225
175
125
T.S.N 8
A
25
B
75
25
C
125
75
25
D
175
125
75
E
200
150
125
F
225
200
175
T.S.N 12
A
75
25
B
125
75
25
C
150
125
75
D
200
175
125
E
225
200
175
F
250
225
200
Chemical Composition Requirement & Mechanical properties
