High Tensile Strength
Reliable load-bearing capacity for industrial machinery and structural components.
UNDERSTANDING SG / DUCTILE IRON CASTINGS
Why SG /
Ductile Iron Castings?
SG / Ductile Iron castings are widely preferred for their superior combination of strength, ductility, toughness and fatigue resistance compared to conventional grey cast iron.
The spheroidal graphite structure reduces stress concentration, allowing SG iron to withstand higher mechanical loads, impact conditions and cyclic loading. This makes it suitable for many structural and load-bearing applications across industrial sectors.
Key Advantages
Excellent Ductility
Ability to undergo controlled deformation before fracture.
Fatigue Resistance
Improved performance under repeated and cyclic mechanical loading.
Good Machinability
Suitable for precision machining and dimensional finishing.
Impact Toughness
Selected grades offer good resistance to sudden mechanical loads.
Design Flexibility
Supports complex casting geometries and engineered component designs.
THE SPHEROIDAL GRAPHITE ADVANTAGE
Engineered Graphite Structure
for Superior Mechanical Performance
The outstanding mechanical properties of SG iron are primarily attributed to the spherical shape of graphite particles within its metallic matrix.
Unlike grey cast iron, which contains sharp graphite flakes that act as stress concentration points, SG iron contains rounded graphite nodules that reduce localized stress concentration and improve resistance to crack initiation and propagation.
Grey Cast Iron
Flake graphite structure with higher localized stress concentration and comparatively brittle behavior.
SG / Ductile Iron
Spherical graphite nodules improve ductility, strength, toughness, and fatigue resistance.
How Spheroidal Graphite Improves Performance
Minimizes Stress Concentration
Spherical graphite nodules reduce localized stress concentration around graphite particles.
Better Resistance to Crack Propagation
Rounded graphite nodules improve resistance to crack initiation and growth.
Improves Ductility
Enhances ductility and resistance to brittle fracture.
Supports Multiple Matrix Structures
Suitable for ferritic, pearlitic, and mixed matrix structures.
Enhances Fatigue Performance
Provides better performance under repeated and cyclic mechanical loading.
Enables Grade Selection
Allows selection of appropriate material grades for different engineering applications.
INTERNATIONAL STANDARDS & GRADE SPECIFICATIONS
SG / Ductile Iron Grades
Across International Standards
SG / Ductile Iron standards cover general engineering grades, ausferritic (ADI), austenitic and special-service materials. General SG grades are primarily classified by mechanical properties; chemistry and other requirements depend on the specified standard and grade.
Understanding these standards helps manufacturers, equipment suppliers, and industrial buyers select suitable ductile iron grades based on application conditions, strength, toughness, and engineering specifications.
Although grade designations may differ between countries, many standards cover comparable families of ferritic, ferritic–pearlitic and pearlitic ductile iron castings. Exact equivalence and grade selection must be confirmed against the applicable standard edition.
Cross-Reference: International Casting Standards Worldwide
| Country / Region | Applicable Standards | Grades |
|---|---|---|
| India | IS 1865:1991, IS 5788:1986, IS 5789:1993, IS 2749:1974, IS 8329:2000, IS 9523:2000, IS 7754, IS 8350 | SG 350/22, SG 400/18, SG 400/15, SG 450/10, SG 500/7, SG 600/3, SG 700/2, SG 800/2, SG 900/2; A-suffix grades; H300, H330; ASG series |
| USA | ASTM A536, A395/A395M, A897/A897M, A439/A439M, A571/A571M, A874/A874M, A1095, A476/A476M; SAE J434, J2477; ASTM A716, A746, A834, A247, A327/A327M | 60-40-18, 65-45-12, 80-55-06, 100-70-03, 120-90-02; ADI grades; D-series; SAE automotive grades |
| Germany | DIN EN 1563, DIN EN 1564, DIN EN 16124, DIN EN 13835, DIN EN 16482, DIN EN 545, DIN EN 598, DIN EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| Europe | EN 1563, EN 1564, EN 16124, EN 13835, EN 16482, EN 545, EN 598, EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| China | GB/T 1348-2019, GB/T 24733-2023, GB/T 26648 | QT400-18, QT450-10, QT500-7, QT600-3, QT700-2, QT800-2; ADI grades; austenitic nodular grades |
| Japan | JIS G 5502:2022 + Amd.1:2024, JIS G 5503:2024, JIS G 5504:2005, JIS G 5510:2012 | FCD series; FCAD series; FCD-LT series; FCDA series |
| United Kingdom | BS EN 1563, BS EN 1564, BS EN 16124, BS EN 13835, BS EN 16482, BS EN 545, BS EN 598, BS EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| France | NF EN 1563, NF EN 1564, NF EN 16124, NF EN 13835, NF EN 16482, NF EN 545, NF EN 598, NF EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| Italy | UNI EN 1563, UNI EN 1564, UNI EN 16124, UNI EN 13835, UNI EN 16482, UNI EN 545, UNI EN 598, UNI EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| Australia | AS 1831, AS 1833 | 400-15, 450-10, 500-7, 600-3, 700-2; austenitic nodular grades |
| South Africa | SANS 936 / SABS 936; SANS 937 / SABS 937 (legacy references) | SG38, SG42, SG50, SG60, SG70; austenitic SG grades |
| Russia | GOST 7293-85 | ВЧ35, ВЧ40, ВЧ45, ВЧ50, ВЧ60, ВЧ70 |
| Spain | UNE-EN 1563, UNE-EN 1564, UNE-EN 16124, UNE-EN 13835, UNE-EN 16482, UNE-EN 545, UNE-EN 598, UNE-EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| Sweden | SS-EN 1563, SS-EN 1564, SS-EN 16124, SS-EN 13835, SS-EN 16482, SS-EN 545, SS-EN 598, SS-EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| Norway | NS-EN 1563, NS-EN 1564, NS-EN 16124, NS-EN 13835, NS-EN 16482, NS-EN 545, NS-EN 598, NS-EN 969; EN 1559-1 / -3; EN ISO 945-1 | EN-GJS-350-22, 400-18, 400-15, 450-10, 500-7, 600-3, 700-2, 800-2, 900-2; EN-GJS-450-18, 500-14, 600-10; EN-GJS-800-10, 900-8, 1050-6, 1200-3, 1400-1; EN-GJSA |
| South Korea | SPS-KFCA-D4302-5016; KS D 4302 (withdrawn) | GCD series |
COUNTRY-WISE MATERIAL GRADES
Interactive Country-Wise Chemical Composition Tables
Select a country to explore SG / Ductile Iron casting grades and typical chemical composition ranges for comparable SG iron grade families.
IS 1865:1991 — Iron Castings with Spheroidal or Nodular Graphite
| Grade | C % | Si % | Mn % | P % | S % | Mg % |
|---|---|---|---|---|---|---|
| SG 350/22 | 3.50–3.80 | 1.80–2.10 | 0.20 max | 0.03 max | 0.015 max | 0.03–0.06 |
| SG 400/18 | 3.50–3.80 | 2.20–2.80 | 0.10–0.30 | 0.06 max | 0.02 max | 0.03–0.06 |
| SG 400/15 | 3.50–3.80 | 2.20–2.80 | 0.10–0.30 | 0.06 max | 0.02 max | 0.03–0.06 |
| SG 450/10 | 3.40–3.80 | 2.40–2.90 | 0.10–0.40 | 0.05 max | 0.02 max | 0.03–0.06 |
| SG 500/7 | 3.40–3.80 | 2.20–2.80 | 0.20–0.50 | 0.06 max | 0.02 max | 0.03–0.06 |
| SG 600/3 | 3.40–3.70 | 2.10–2.80 | 0.30–0.60 | 0.06 max | 0.02 max | 0.03–0.06 |
| SG 700/2 | 3.30–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
| SG 800/2 | 3.20–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
Typical grade-family chemistry (mass %), not standard limits or exact grade equivalence. Final chemistry varies with the casting and process.
IS 1865 grades are property-based; the ranges above are typical guidance, not mandatory IS chemistry limits.
IS 5788:1986 — SG Iron Pressure Castings for Elevated Temperatures
| Material | C % min | Si % max | P % max |
|---|---|---|---|
| Ferritic SG pressure castings | 3.00 | 2.50* | 0.08 |
*Si may increase by 0.08% for each 0.01% reduction in P below 0.08%, up to 2.75% Si. Other element limits are not specified in the chemistry clause.
IS 5789:1993 — Austenitic SG Pressure Castings for Low Temperatures
| Material | C % | Si % | Mn % | Ni % | Cr % max | P % max |
|---|---|---|---|---|---|---|
| Austenitic SG pressure castings | 2.2–2.7* | 1.5–2.5 | 3.75–4.5 | 21.0–24.0 | 0.10 | 0.08 |
*For sections below 6 mm, the standard notes that carbon may be adjusted to 2.90% maximum.
IS 2749:1974 — Austenitic Iron Castings (SG / Nodular Grades)
| Grade | C % max | Si % | Mn % | Ni % | Cr % | P % max | Cu % max |
|---|---|---|---|---|---|---|---|
| ASG Ni13Mn7 | 3.0 | 2.0–3.0 | 6.0–7.0 | 12.0–14.0 | 0.2 max | 0.080 | 0.5 |
| ASG Ni20Cr2 | 3.0 | 1.5–3.0 | 0.5–1.5 | 18.0–22.0 | 1.0–2.5 | 0.080 | 0.5 |
| ASG Ni20Cr3 | 3.0 | 1.5–3.0 | 0.5–1.5 | 18.0–22.0 | 2.5–3.5 | 0.080 | 0.5 |
| ASG Ni20Si5Cr2 | 3.0 | 4.5–5.5 | 0.5–1.5 | 18.0–22.0 | 1.0–2.5 | 0.080 | 0.5 |
| ASG Ni22 | 3.0 | 1.0–3.0 | 1.5–2.5 | 21.0–24.0 | 0.5 max | 0.080 | 0.5 |
| ASG Ni23Mn4 | 2.6 | 1.5–2.5 | 4.0–4.5 | 22.0–24.0 | 0.2 max | 0.080 | 0.5 |
| ASG Ni30Cr1 | 2.6 | 1.5–3.0 | 0.5–1.5 | 28.0–32.0 | 1.0–1.5 | 0.080 | 0.5 |
| ASG Ni30Cr3 | 2.6 | 1.5–3.0 | 0.5–1.5 | 28.0–32.0 | 2.5–3.5 | 0.080 | 0.5 |
| ASG Ni30Si5Cr5 | 2.6 | 5.0–6.0 | 0.5–1.5 | 28.0–32.0 | 4.5–5.5 | 0.080 | 0.5 |
| ASG Ni35 | 2.4 | 1.5–3.0 | 0.5–1.5 | 34.0–36.0 | 0.2 max | 0.080 | 0.5 |
| ASG Ni35Cr3 | 2.4 | 1.5–3.0 | 0.5–1.5 | 34.0–36.0 | 2.0–3.0 | 0.080 | 0.5 |
Mass %. ASG grades only; AFG flake-graphite grades excluded. Refer to the ordered standard and amendments.
ASTM A536 — Ductile Iron Castings
| Grade | C % | Si % | Mn % | P % | S % | Mg % |
|---|---|---|---|---|---|---|
| 60-40-18 | 3.50–3.80 | 2.20–2.80 | 0.10–0.30 | 0.06 max | 0.02 max | 0.03–0.06 |
| 65-45-12 | 3.40–3.80 | 2.40–2.90 | 0.10–0.40 | 0.05 max | 0.02 max | 0.03–0.06 |
| 80-55-06 | 3.40–3.70 | 2.10–2.80 | 0.30–0.60 | 0.06 max | 0.02 max | 0.03–0.06 |
| 100-70-03 | 3.30–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
| 120-90-02 | 3.20–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
Typical grade-family chemistry (mass %), not standard limits or exact grade equivalence. Final chemistry varies with the casting and process.
Typical chemistry above is guidance, not ASTM acceptance limits. Property grades: 60-40-18, 65-45-12, 80-55-06, 100-70-03, 120-90-02.
ASTM A395/A395M — Ferritic SG Pressure Castings
| Grade | C % min | Si % max | P % max |
|---|---|---|---|
| 60-40-18 | 3.00 | 2.50* | 0.08 |
| 65-45-15 | 3.00 | 2.50* | 0.08 |
*For each 0.01% reduction in P below 0.08%, Si may increase by 0.08%, up to 2.75%. A395/A395M-99(2018) reference.
ASTM A439/A439M — Austenitic Ductile Iron
| Grade | C % max | Si % | Mn % | Ni % | Cr % | P % max |
|---|---|---|---|---|---|---|
| D-2 | 3.00 | 1.50–3.00 | 0.70–1.25 | 18.00–22.00 | 1.75–2.75 | 0.08 |
| D-2B | 3.00 | 1.50–3.00 | 0.70–1.25 | 18.00–22.00 | 2.75–4.00 | 0.08 |
| D-2C | 2.90 | 1.00–3.00 | 1.80–2.40 | 21.00–24.00 | 0.50 max* | 0.08 |
| D-2S | 2.60 | 4.80–5.80 | 1.00 max | 24.00–28.00 | 1.75–2.25 | 0.08 |
| D-3 | 2.60 | 1.00–2.80 | 1.00 max* | 28.00–32.00 | 2.50–3.50 | 0.08 |
| D-3A | 2.60 | 1.00–2.80 | 1.00 max* | 28.00–32.00 | 1.00–1.50 | 0.08 |
| D-4 | 2.60 | 5.00–6.00 | 1.00 max* | 28.00–32.00 | 4.50–5.50 | 0.08 |
| D-5 | 2.40 | 1.00–2.80 | 1.00 max* | 34.00–36.00 | 0.10 max | 0.08 |
| D-5B | 2.40 | 1.00–2.80 | 1.00 max* | 34.00–36.00 | 2.00–3.00 | 0.08 |
| D-5S | 2.30 | 4.90–5.50 | 1.00 max | 34.00–37.00 | 1.75–2.25 | 0.08 |
Mass %. A439/A439M-18, Table 1 reference. *Not intentionally added. Check the ordered edition and all footnotes.
ASTM A571/A571M — Low-Temperature Austenitic SG Pressure Castings
| Class | C % | Si % | Mn % | Ni % | Cr % max | P % max |
|---|---|---|---|---|---|---|
| Class 1 | 2.2–2.7* | 1.50–2.50 | 3.75–4.50 | 21.00–24.00 | 0.20 | 0.08 |
| Class 2 | 2.2–2.7* | 1.50–2.50 | 3.75–4.50 | 21.00–24.00 | 0.20 | 0.08 |
D-2M chemistry: A571/A571M-01(2019) reference. *Apply standard thin-section carbon provisions and class-specific impact requirements.
ASTM A874/A874M — Low-Temperature Ferritic Ductile Iron
| Material | C % | Si % | Mn % max | P % max | Mg % max | Cu % max | Ni % max | Cr % max |
|---|---|---|---|---|---|---|---|---|
| Ferritic SG | 3.0–3.7 | 1.2–2.3 | 0.25 | 0.03 | 0.07 | 0.10 | 1.00 | 0.07 |
Carbon equivalent C + Si/3: 4.5% maximum. A874/A874M-98(2022) reference.
ASTM A1095 — High-Silicon Molybdenum Ferritic Iron (SG SiMo)
| Grade | C % | Si % | Mo % | Mn % max | P % | S % max | Mg % max | Ti % max |
|---|---|---|---|---|---|---|---|---|
| SG SiMo | 2.90–3.70 | 3.50–4.80 | 0.40–1.50 | 0.50 | 0.02–0.05 | 0.02 | 0.06 | 0.05 |
Additional maxima (%): Ni 0.50, Cu 0.30, W 0.30, V 0.10, Nb 0.30, Cr 0.50; Fe balance. A1095-15 reference. MG/CG graphite types excluded.
ASTM A476/A476M — Ductile Iron for Paper-Mill Dryer Rolls
| Material | C % min | Si % max | P % max | S % max | Carbon equivalent % |
|---|---|---|---|---|---|
| Dryer-roll SG | 3.00 | 3.00 | 0.08 | 0.05 | 3.8–4.5 |
Carbon equivalent = C + 0.3(Si + P). A476/A476M-00(2022) reference.
DIN EN 1563 / EN 1563 — Spheroidal Graphite Cast Iron
| Grade | C % | Si % | Mn % | P % | S % | Mg % |
|---|---|---|---|---|---|---|
| EN-GJS-350-22 | 3.50–3.80 | 1.80–2.10 | 0.20 max | 0.03 max | 0.015 max | 0.03–0.06 |
| EN-GJS-400-18 | 3.50–3.80 | 2.20–2.80 | 0.10–0.30 | 0.06 max | 0.02 max | 0.03–0.06 |
| EN-GJS-400-15 | 3.50–3.80 | 2.20–2.80 | 0.10–0.30 | 0.06 max | 0.02 max | 0.03–0.06 |
| EN-GJS-450-10 | 3.40–3.80 | 2.40–2.90 | 0.10–0.40 | 0.05 max | 0.02 max | 0.03–0.06 |
| EN-GJS-500-7 | 3.40–3.80 | 2.20–2.80 | 0.20–0.50 | 0.06 max | 0.02 max | 0.03–0.06 |
| EN-GJS-600-3 | 3.40–3.70 | 2.10–2.80 | 0.30–0.60 | 0.06 max | 0.02 max | 0.03–0.06 |
| EN-GJS-700-2 | 3.30–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
| EN-GJS-800-2 | 3.20–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
Typical grade-family chemistry (mass %), not standard limits or exact grade equivalence. Final chemistry varies with the casting and process.
Existing numeric ranges are typical guidance, not standard chemistry limits. Sample-route suffixes depend on the ordered edition.
DIN EN 16124 / EN 16124 — High-Temperature Ferritic SiMo Iron
| Grade | Si % | Mo % |
|---|---|---|
| EN-GJS-SiMo25-5 | 2.3–2.7 | 0.4–0.6 |
| EN-GJS-SiMo30-7 | 2.8–3.2 | 0.6–0.8 |
| EN-GJS-SiMo35-5 | 3.3–3.7 | 0.4–0.6 |
| EN-GJS-SiMo40-6 | 3.8–4.2 | 0.5–0.7 |
| EN-GJS-SiMo40-10 | 3.8–4.2 | 0.8–1.1 |
| EN-GJS-SiMo45-6 | 4.3–4.7 | 0.5–0.7 |
| EN-GJS-SiMo45-10 | 4.3–4.7 | 0.8–1.1 |
| EN-GJS-SiMo50-6 | 4.8–5.2 | 0.5–0.7 |
| EN-GJS-SiMo50-10 | 4.8–5.2 | 0.8–1.1 |
EN 16124:2011, Table 1. Other element contents are manufacturer-controlled unless agreed.
DIN EN 13835 / EN 13835 — Austenitic SG Iron
| Grade | C % max | Si % | Mn % | Ni % | Cr % | P % max | Cu % max |
|---|---|---|---|---|---|---|---|
| EN-GJSA-XNiCr20-2 | 3.0 | 1.5–3.0 | 0.5–1.5 | 18.0–22.0 | 1.0–3.5 | 0.08 | 0.50 |
| EN-GJSA-XNiMn23-4 | 2.6 | 1.5–2.5 | 4.0–4.5 | 22.0–24.0 | 0.2 max | 0.08 | 0.50 |
| EN-GJSA-XNiCrNb20-2 | 3.0 | 1.5–2.4 | 0.5–1.5 | 18.0–22.0 | 1.0–3.5 | 0.08 | 0.50 |
| EN-GJSA-XNi22 | 3.0 | 1.0–3.0 | 1.5–2.5 | 21.0–24.0 | 0.5 max | 0.08 | 0.50 |
| EN-GJSA-XNi35 | 2.4 | 1.5–3.0 | 0.5–1.5 | 34.0–36.0 | 0.2 max | 0.08 | 0.50 |
| EN-GJSA-XNiSiCr35-5-2 | 2.0 | 4.0–6.0 | 0.5–1.5 | 34.0–36.0 | 1.5–2.5 | 0.08 | 0.50 |
| EN-GJSA-XNiMn13-7 | 3.0 | 2.0–3.0 | 6.0–7.0 | 12.0–14.0 | 0.2 max | 0.08 | 0.50 |
| EN-GJSA-XNiCr30-3 | 2.6 | 1.5–3.0 | 0.5–1.5 | 28.0–32.0 | 2.5–3.5 | 0.08 | 0.50 |
| EN-GJSA-XNiSiCr30-5-5 | 2.6 | 5.0–6.0 | 0.5–1.5 | 28.0–32.0 | 4.5–5.5 | 0.08 | 0.50 |
| EN-GJSA-XNiCr35-3 | 2.4 | 1.5–3.0 | 0.5–1.5 | 34.0–36.0 | 2.0–3.0 | 0.08 | 0.50 |
EN 13835:2012 reference; SG grades only. Nb grades also require the standard’s Nb/Mg/Si weldability provisions.
GB/T 1348-2019 — Spheroidal Graphite Iron Castings
| Grade | C % | Si % | Mn % | P % | S % | Mg % |
|---|---|---|---|---|---|---|
| QT400-18 | 3.6–3.8 | 2.3–2.7 | <0.5 | <0.08 | <0.025 | 0.03–0.05 |
| QT400-15 | 3.5–3.6 | 3.0–3.2 | <0.5 | <0.07 | <0.02 | 0.04 |
| QT450-10 | 3.4–3.9 | 2.7–3.0 | 0.2–0.5 | <0.07 | <0.03 | 0.06–0.10 |
| QT500-7 | 3.6–3.8 | 2.5–2.9 | <0.6 | <0.08 | <0.025 | 0.03–0.05 |
| QT600-3 | 3.6–3.8 | 2.0–2.4 | 0.5–0.7 | <0.08 | <0.025 | 0.035–0.05 |
| QT700-2 | 3.7–4.0 | 2.3–2.6 | 0.5–0.8 | <0.08 | <0.02 | 0.035–0.065 |
| QT800-2 | 3.20–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
Typical grade-family chemistry (mass %), not standard limits or exact grade equivalence. Final chemistry varies with the casting and process.
Existing numeric chemistry is typical guidance, not mandatory GB limits. Impact and test-sample suffixes require the ordered standard.
JIS G 5502:2022 + Amendment 1:2024 — Spheroidal Graphite Cast Iron
| Grade | C % | Si % | Mn % | P % | S % | Mg % |
|---|---|---|---|---|---|---|
| FCD400-15 | 3.50–3.80 | 2.20–2.80 | 0.10–0.30 | 0.06 max | 0.02 max | 0.03–0.06 |
| FCD450-10 | 3.40–3.80 | 2.40–2.90 | 0.10–0.40 | 0.05 max | 0.02 max | 0.03–0.06 |
| FCD500-7 | 3.40–3.80 | 2.20–2.80 | 0.20–0.50 | 0.06 max | 0.02 max | 0.03–0.06 |
| FCD600-3 | 3.40–3.70 | 2.10–2.80 | 0.30–0.60 | 0.06 max | 0.02 max | 0.03–0.06 |
| FCD700-2 | 3.30–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
| FCD800-2 | 3.20–3.60 | 2.00–2.70 | 0.40–0.80 | 0.06 max | 0.02 max | 0.03–0.06 |
Typical grade-family chemistry (mass %), not standard limits or exact grade equivalence. Final chemistry varies with the casting and process.
Existing numeric chemistry is typical guidance.
JIS G 5504:2005 — Heavy-Walled Low-Temperature Ferritic SG Iron
| Grade / application | C % | Si % | Mn % max | P % max | Cu % max | Ni % max | Cr % max | Mg % max |
|---|---|---|---|---|---|---|---|---|
| FCD300LT — cask application | 3.0–3.7 | 1.2–2.3 | 0.25 | 0.03 | 0.10 | 1.00 | 0.07 | 0.07 |
Cask-application limits only, not universal FCD300LT chemistry. General composition is agreed between purchaser and manufacturer.
JIS G 5510:2012 — Austenitic Iron Castings (FCDA Grades)
| Grade | C % max | Si % | Mn % | Ni % | Cr % | P % max | Cu % max |
|---|---|---|---|---|---|---|---|
| FCDA-NiCr20-2 | 3.0 | 1.5–3.0 | 0.5–1.5 | 18.0–22.0 | 1.0–3.5 | 0.08 | 0.50 |
| FCDA-NiCr30-3 | 2.6 | 1.5–3.0 | 0.5–1.5 | 28.0–32.0 | 2.5–3.5 | 0.08 | 0.50 |
| FCDA-Ni35 | 2.4 | 1.5–3.0 | 0.5–1.5 | 34.0–36.0 | 0.2 max | 0.08 | 0.50 |
| FCDA-NiSiCr35-5-2 | 2.0 | 4.0–6.0 | 0.5–1.5 | 34.0–36.0 | 1.5–2.5 | 0.08 | 0.50 |
Verified representative FCDA chemistry. FCA flake-graphite grades excluded.
STEP-BY-STEP MANUFACTURING PROCESS
From Molten Metal to
Precision-Engineered SG Iron Castings
The SG iron casting process requires controlled melting, magnesium treatment, inoculation, pouring, solidification, and inspection to achieve the required graphite morphology and mechanical properties.
This process flow outlines the key stages involved in producing SG / Ductile Iron castings. Control over melt chemistry, nodularization, inoculation, moulding, and inspection helps achieve the required spheroidal graphite structure and performance characteristics.
Raw Material Selection
Selection of suitable metallic charge materials, foundry returns, and alloy additions.
Melting & Temperature Control
Melting of the charge in a suitable furnace with controlled melt temperature.
Chemical Composition Adjustment
Adjustment of carbon, silicon, manganese, and other specified elements.
Magnesium Treatment
Treatment with suitable nodularizing alloys to promote spherical graphite formation.
Inoculation
Addition of suitable inoculants to improve graphite nucleation and solidification behavior.
Mould & Core Preparation
Preparation of moulds and cores according to component geometry and casting requirements.
Pouring & Solidification
Controlled pouring into prepared moulds and management of solidification conditions.
Shakeout & Fettling
Removal of moulding material, gating systems, risers, and surface projections.
Heat Treatment (If Required)
Application of ferritizing, normalizing, stress relieving, or austempering when specified.
Inspection & Testing
Verification of chemical, mechanical, dimensional, and microstructural requirements.
Machining & Surface Finishing
Machining and finishing to customer drawings where included in the supply scope.
Final Inspection & Dispatch
Final quality verification, identification, packaging, and dispatch.
ⓘ This workflow is a general technical process for SG / Ductile Iron castings. Specific production controls may vary based on grade, casting geometry, section thickness, and customer specifications.
06SG / DUCTILE IRON PRODUCT RANGE & SUBPRODUCTS
Engineered SG Iron Components
for Industrial Applications
SG / Ductile Iron Castings are suitable for manufacturing components that require mechanical strength, dimensional stability, machinability, and resistance to repeated operational loads.
01
Pump Castings & Components
Durable cast components for industrial pumping and fluid-handling systems.
Subproducts:
Pump casings, volute casings, impeller housings, pump covers, bearing housings, end covers, suction and discharge bodies.
02
Valve Bodies & Fittings
Cast components designed for suitable industrial fluid-control applications.
Subproducts:
Gate valve bodies, butterfly valve bodies, check valve bodies, valve bonnets, flanges, pipe couplings, elbows and tees.
03
Gears & Power Transmission Components
Precision castings for mechanical power transmission systems.
Subproducts:
Gear blanks, gear wheels, pulleys, flywheels, sprocket blanks, coupling hubs and transmission housings.
04
Automotive & Transportation Castings
Engineered components for automotive and transportation applications.
Subproducts:
Steering knuckles, wheel hubs, axle housings, differential housings, suspension brackets and selected brake components.
05
Heavy Machinery Castings
High-strength components for industrial machinery and equipment.
Subproducts:
Gearbox housings, machine bases, support frames, bearing blocks, equipment covers and mounting brackets.
06
Agricultural Machinery Castings
Cast components for farm equipment and agricultural machinery.
Subproducts:
Tractor housings, wheel hubs, axle supports, cultivator brackets, transmission cases and implement mounts.
07
Hydraulic & Engineering Components
Strong, machinable castings for mechanical and hydraulic equipment.
Subproducts:
Hydraulic end covers, manifold housings, actuator housings, bearing supports and mounting blocks.
08
Infrastructure & Utility Castings
Reliable components for municipal and industrial infrastructure.
Subproducts:
Manhole covers, frames, drainage gratings, pipe fittings, waterworks components and utility covers.
MECHANICAL & PHYSICAL PROPERTIES
Mechanical Performance Across
SG / Ductile Iron Grades
SG iron offers a wide range of mechanical properties, enabling engineers to select materials based on tensile strength, yield strength, elongation, hardness, and operating requirements.
Grade-Wise Mechanical Properties
| Grade | Tensile Min. (MPa) | Proof Stress Min. (MPa) | Elongation Min. (%) | Indicative Hardness (HBW) |
|---|---|---|---|---|
| SG 350/22 | 350 | 220 | 22 | Below 160 |
| SG 400/18 | 400 | 250 | 18 | 130–175 |
| SG 400/15 | 400 | 250 | 15 | 135–180 |
| SG 450/10 | 450 | 310 | 10 | 170–200 |
| SG 500/7 | 500 | 320 | 7 | 160–210 |
| SG 600/3 | 600 | 370 | 3 | 190–270 |
| SG 700/2 | 700 | 420 | 2 | 225–305 |
| SG 800/2 | 800 | 480 | 2 | 245–335 |
Representative mechanical values for conventional grade classifications. Hardness ranges are indicative and are not guaranteed standard limits. Actual requirements depend on the specified standard, casting section thickness, and test sample.
Physical Properties
| Property | Typical Value |
|---|---|
| Density | 7.0–7.2 g/cm³ |
| Modulus of Elasticity | 160–180 GPa |
| Poisson’s Ratio | 0.27–0.29 |
| Thermal Conductivity | Approximately 25–40 W/m·K |
| Specific Heat Capacity | Approximately 450–550 J/kg·K |
| Thermal Expansion Coefficient | Approximately 11–13 × 10⁻⁶ /K |
| Melting / Solidification Range | Approximately 1,150–1,250°C |
| Magnetic Behavior | Generally ferromagnetic |
Values are approximate and depend on material grade, temperature, matrix structure, and chemical composition.
Tailored Performance
Multiple grades for different strength and ductility needs.
Design Flexibility
Suitable for a wide range of engineering applications.
Reliable Properties
Consistent mechanical and physical characteristics.
Industry Standard
Properties aligned with international specifications.
MICROSTRUCTURE OF SG / DUCTILE IRON CASTINGS
Microstructural Characteristics
and Metallurgical Performance
The microstructure of SG iron consists of spherical graphite nodules distributed within a metallic matrix. The graphite nodularity, nodule count, nodule size, and matrix composition significantly influence mechanical strength, ductility, toughness, hardness, and machinability.
Ferritic Microstructure
Predominantly ferritic matrix containing spherical graphite nodules.
Key Properties
- Excellent ductility
- Good toughness
- High machinability
- Relatively low hardness
Ferritic–Pearlitic Microstructure
Combination of ferrite and pearlite surrounding graphite nodules.
Key Properties
- Balanced tensile strength
- Good elongation
- Good machinability
- Improved wear resistance
Pearlitic Microstructure
Predominantly pearlitic matrix with spherical graphite nodules.
Key Properties
- Higher tensile strength
- Higher hardness
- Better wear resistance
- Reduced elongation
Ausferritic Microstructure (ADI)
Microstructure containing acicular ferrite and carbon-enriched retained austenite.
Key Properties
- High strength
- Good fatigue resistance
- Useful toughness
- Excellent wear performance
Important Microstructural Parameters
| Parameter | Importance |
|---|---|
| Graphite Nodularity | Measures the proportion of graphite present in spheroidal form |
| Nodule Count | Influences graphite distribution and matrix formation |
| Nodule Size | Affects local material behavior and mechanical properties |
| Ferrite Percentage | Influences ductility, toughness, and machinability |
| Pearlite Percentage | Influences hardness, strength, and wear resistance |
| Carbide Content | Excessive carbides may reduce machinability and toughness |
| Graphite Distribution | Helps assess microstructural consistency |
Microstructural features and properties depend on the material grade, chemical composition, cooling conditions, casting section thickness, and heat treatment. The above information is for general guidance and should be verified against the applicable standard and inspection requirements.
QUALITY ASSURANCE & INSPECTION
Comprehensive Testing & Inspection
for Reliable SG / Ductile Iron Castings
Our quality assurance process involves chemical, mechanical, metallurgical, dimensional and non-destructive testing to ensure that every SG / Ductile Iron casting meets the specified material standards and customer requirements.
Inspection & Testing Methods
Verification at Every Stage for Consistent Material Quality
| No. | Inspection / Testing Method | Purpose | Key Details |
|---|---|---|---|
| 01 | Chemical Analysis | Verification of melt composition | Elemental analysis using spectrometers (e.g., OES) as per applicable standards. |
| 02 | Tensile Testing | Measurement of tensile strength, proof stress and elongation | Evaluates mechanical properties as per standard requirements (e.g., IS 1865, EN 1563, ASTM A536). |
| 03 | Hardness Testing | Verification of specified hardness | Brinell hardness testing (HBW) on as-cast and heat-treated components. |
| 04 | Metallographic Examination | Evaluation of graphite nodularity, nodule count and matrix structure | Microstructural analysis to assess graphite morphology, ferrite/pearlite ratio and inclusion content. |
| 05 | Dimensional Inspection | Verification of casting dimensions and tolerances | Inspection using calipers, height gauges, CMM and templates as per drawings. |
| 06 | Visual Inspection | Identification of visible surface defects | Surface condition, fins, blowholes, misruns and general casting appearance. |
| 07 | Ultrasonic Testing (UT) | Detection of internal discontinuities | Ultrasonic examination for internal defects as per applicable standards. |
| 08 | Magnetic Particle Testing (MT) | Detection of surface and near-surface discontinuities | Magnetic particle inspection for cracks and surface defects. |
| 09 | Liquid Penetrant Testing (PT) | Detection of surface-breaking defects | Dye penetrant examination for non-magnetic materials and surface defects. |
| 10 | Pressure / Leak Testing | Verification of pressure-containing castings where specified | Hydrostatic or air pressure testing as per customer and standard requirements. |
Testing Facilities
Key Testing Capabilities for Material and Casting Verification
Chemical Analysis
Spectrometric analysis (OES)
Tensile Testing
Tensile, proof stress and elongation
Hardness Testing
Brinell hardness testing (HBW)
Metallographic Examination
Graphite nodularity and matrix structure
Dimensional Inspection
CMM and precision measurement
Ultrasonic Testing
Detection of internal defects
Magnetic Particle Testing
Surface and near-surface defects
Liquid Penetrant Testing
Surface-breaking defects
Pressure / Leak Testing
Hydrostatic / air pressure testing
Quality Documentation
Complete Test Records and Traceability
Depending on customer requirements, we provide complete quality documentation including material test certificates, chemical analysis reports, tensile test results, hardness records, metallographic examination reports, dimensional inspection reports, non-destructive testing records and pressure test reports.
Material Test Certificates
Chemical Analysis Reports
Mechanical Test Results
Metallographic Reports
Dimensional Inspection Reports
NDT Reports
Pressure Test Reports
ⓘ The tests and inspection facilities shown are representative of typical quality assurance practices for SG / Ductile Iron castings. Actual testing scope, methods and documentation will be as per customer requirements, applicable standards and availability through BSCPL or its approved testing partners.
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SG / Ductile Iron Castings
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