Full name of S.G. Iron is Spheroidal Graphite Iron also called as Nodular OR Ductile Iron. In Graded cast iron graphite appears in the form of flakes, which gives minute fracture lines within the structure of the iron while in S.G.Iron the graphite is modified by small addition of magnesium. The magnesium causes the graphite to "ball" whilst still in molten solution, in solidifying; the graphite remains in this spheroidal shape and creates a matrix with no built in fracture lines.
This
modified structure gives S.G.Iron a greater ability
to bend before fracture, an increase in ductility and
resistance to shock allowing suitable alternatives to
some carbon steel and malleable irons.
Before the advent of
European Material numbers the descriptive code (xxx
/ yy) represented the following physical properties.
xxx - Number : Represents tensile strength
in N / mm2
yy- Number : Represents % elongation
before fracture.
(i.e. 420 / 12 = 420 N / mm2 tensile
strength and 12% Elongation.)
S.G.
Iron Technical specification:
MetricN/mm2
/ % Elongation.
BS 2789 : 1985 |
ImperialTons/In2/
%
Elongation |
New
European Material Number.
EN 1563 : 1997 |
Material
Description |
Hardness |
900
/ 2 |
47
/ 2 |
EN-JS-1090 |
High
strength, Low ductility and Hard |
302
– 359 BHN |
800
/ 2 |
47
/ 2 |
EN-JS-1080 |
High
strength, Low ductility |
190
– 350 BHN |
700
/ 2 |
47
/ 2 |
EN-JS-1070 |
High
strength, Low ductility |
190
– 350 BHN |
600
/ 3 |
37
/ 2 |
EN-JS-1060 |
High
strength, low Ductility |
190
– 350 BHN |
500
/ 7 |
32
/ 7 |
EN-JS-1050 |
Strength
with reasonable ductility |
160
– 240 BHN |
450
/ 10 |
32
/ 7 |
EN-JS-1040 |
Strength
with reasonable ductility |
160
– 240 BHN |
420
/ 12 |
27
/ 12 |
EN-JS-1030 |
Strength
with reasonable ductility |
212
Max BHN |
400
/ 18 |
24
/ 17 |
EN-JS-1020 |
High
resistance to Impact |
180
Max BHN |
350
/ 22 |
|
EN-JS-1010 |
High
resistance to Impact |
180
Max BHN |
S.G.Iron Technical Specification for South Africa: SABS 936 / 937
Grade |
Tensile
Strength in
N / mm2 |
Proof
Stress in
N / mm2 |
Elongation
(Min) |
Hardness |
Structure |
SG38 |
375 |
245 |
17 |
<
180 BHN |
Ferrite |
SG42 |
410 |
275 |
12 |
<
200 BHN |
Ferrite |
SG50 |
490 |
345 |
7 |
170
– 240 BHN |
Ferrite
& Pearlite |
SG60 |
590 |
390 |
4 |
210
– 250 BHN |
Pearlite |
SG70 |
685 |
440 |
3 |
230
– 300 BHN |
Pearlite |
|
Technical
Information