AISI 430 Ferritic Stainless Steel Microstucture
AISI 430 Ferritic Stainless Steel Microstucture
AISI 430 Ferritic Stainless Steel Microstucture
2, 160-166
MATERIALS PREPARATION
(2)
Lancaster (1993) classified welding current range 50170A as relatively low heat input process. The range of
heat input per unit length considered in the present work
is highlighted in Table 2. Heat input rates per unit length
of weld between 205J/mm and 2.3KJ/mm corresponding
to welding current 50-160A and speed 1-3.5mm/s were
considered.
In the present study, the heat input rate per unit length of
the weld is evaluated from the relationship provided by
Easterling (1993)
H I =
IV
(1)
161
Table 1: Standard specification of AISI 430 ferritic stainless steel (Kaltenhauser 1971)
Material
Spec.
AISI 430
Composition
C
Cr
Ni
Si
Mn
Mo
Cu
Ti
0.12
16-18
0.75
1.0
0.040
0.30
Table 2: Tabular listing of heat input and welding speed for experimental runs
S/N
Weld No
1.5
2.5
3.5
FSS 430_50
50 A X 30V
720
480
360
288
240
205.7
FSS 430_60
60 A X 30V
864
576
432
345.6
288
246.8
FSS 430_70
70 A X 30V
1008
672
504
403.2
336
288
FSS 430_80
80 A X 30V
1152
768
576
460.8
384
329.1
FSS 430_90
90 A X 30V
1296
864
648
518.4
432
369.9
FSS 430_100
100 A X 30V
1440
960
720
576
480
414
FSS 430_110
110 A X 30V
1584
1056
792
633.6
528
452.5
FSS 430_120
120 A X 30V
1728
1152
864
691.2
576
493.7
FSS 430_130
130 A X 30V
1872
1248
936
748.8
624
534.8
10
FSS 430_140
140 A X 30V
2016
1344
1008
806.4
672
576
11
FSS 430_150
150 A X 30V
2160
1440
1080
864
720
617.1
12
FSS 430_160
160 A X 30V
2304
1536
1152
921.6
768
658.24
162
Figure 2: As-received AISI 430 ferritic stainless steel, streak of martensite in ferrite matrix
163
165
CONCLUSION
The microstructural feature of AISI 430 ferritic stainless
steel weld produced under different range of heat input
rates has been investigated in terms of phases and
morhologies. It has been observed that irrespective of the
welding condition, the primary solidification structure
changed from a predominantly ferritic structure to a
matrix interspersed with increasing fraction of interdendritic martensite in the weld metal and grain
boundary martensite in the heat affected zone. The
martensite distribution in the steel falls within the
Kaltenhauser ferrite factor for the formation of austenite
in the high temperature transformation zone. The grain
morphologies alternates between columnar and equiaxed
grains depending on the welding speed within a given
current. However, welding speed of 3.5mm/s appears to
generally lead to the production of equiaxed grains.AT
welding current below the critical level, the
microstructural features of the weld is influenced by the
combination of welding current and speed. This implies
that below the critical welding current value, the
mechanical properties of ferritic steel weld might be
influenced by both the welding current and the speed.
ACKNOWLEDGEMENTS
This research is supported by a grant from the Research
Management Centre, International Islamic University,
Malaysia, under grant number EDW B0804-131.
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