Hubs and flanged parts
Mark the central fit, hole pattern and face runout, and state which surfaces are machined. Ductile iron is a common choice where a hub takes shock loads.
Ductile iron castings · Gaomi, China
Ductile iron castings made to your drawing (nodular / SG iron).
JK Casting is a ductile iron castings manufacturer in Gaomi, Shandong, China. We make ductile iron castings, also called nodular or spheroidal graphite (SG) iron, to customer drawings by sand casting, and supply them raw or CNC-machined. Regular grades run from QT400-15 to QT600-3, with the EN-GJS, ASTM A536 and GGG equivalents; higher-strength grades are reviewed part by part.
Ductile iron is a type of cast iron. If you are still choosing between ductile and grey iron, see the ductile vs grey iron guide; grey iron parts are covered on gray and ductile iron castings.
JK Casting workshop photoA core shooting machine makes the sand cores for cored sand castings. The grade and route for your part are confirmed against your drawing.
QT400–QT600Sand castRaw or machinedDrawing-based review
Brackets and mounts
Give the mounting geometry, working loads and the grade. Measurable elongation is the usual reason to choose ductile over grey iron for a loaded bracket.
Higher-duty housings
Identify bores, sealing faces and datums. Housings that see impact or higher stress are often specified in ductile iron instead of grey iron.
Grades we quote
Regular ductile iron grades, with their common equivalents.
In QT and EN-GJS names, the first number is the minimum tensile strength in MPa and the number after the dash is the minimum elongation in percent. Equivalents from different standards are approximate; the standard on the drawing governs, and a substitution needs your written approval.
The ductile iron grades chart gives the full cross-reference with ГОСТ and JIS grades and the minimum yield, tensile and elongation values.
Regular grade band
- QT400-15, QT450-10, QT500-7, QT600-3
- EN-GJS-400-15, EN-GJS-450-10, EN-GJS-500-7, EN-GJS-600-3
- ASTM A536 60-40-18, 65-45-12, 80-55-06
- GGG40, GGG50, GGG60
Grades above this band are reviewed part by part.
Common starting points
- QT400-15: elongation and impact toughness matter most
- QT450-10: general hubs, brackets and housings
- QT500-7: higher strength with moderate elongation
- QT600-3: higher strength, low elongation
These are starting points, not design advice; the designer chooses the grade.
On the drawing
What to specify for a ductile iron casting.
The family name alone does not establish the properties. A complete specification lets the casting, heat treatment and tests be quoted on the same basis by every supplier.
- Grade and governing standard, for example QT450-10 to GB/T 1348 or EN-GJS-450-10 to EN 1563
- Test piece type: separately cast, cast-on or cut from the casting
- Mechanical properties and hardness to be reported
- Any nodularity or microstructure acceptance requirement
- Heat-treatment or delivery condition
- Surface acceptance, repair rules and dimensional reporting
Ductile or grey
Ductile iron vs grey iron, in short.
Grey (gray) iron has flake graphite: it damps vibration, machines easily and usually costs less, but it has almost no elongation. Ductile iron has nodular graphite: it can stretch before breaking and has higher tensile strength, impact and fatigue resistance. Choose ductile when the part needs that toughness; do not swap families without design approval. The ductile vs grey iron guide has a decision table by part type, and the gray iron grades chart lists the grey grades.
Route and supply
Sand casting, machining and inspection.
Ductile iron parts are sand cast. Patterns, moulds and cores are planned from the drawing; JK’s sand casting routes include resin-coated shell moulds, and the route for each part is confirmed against the drawing. See sand casting.
Order raw castings for your own machining line, or include CNC machining of bores, faces and holes. See machined castings.
Material records, dimensional reports and first-article approval are agreed for each order. See the sample approval checklist.
Tooling is quoted separately for each drawing. See casting tooling costs for what to agree on ownership.
Ductile iron RFQ checklist
Send one consistent specification for each part number.
Start with the controlled finished-part drawing and the full material designation. For bores, datums and mounting faces, use the housing RFQ guide.
- Part number, drawing revision, 2D drawing and available 3D model
- Ductile iron grade, governing standard and delivery condition
- Test piece type and the properties to report
- Initial quantity, expected annual demand and delivery batches
- Raw casting or machined supply, with critical fits and datums marked
- Surface acceptance, coating, identification and packing
Buyer questions
Before requesting a ductile iron casting quotation.
Is SG iron the same as ductile iron?
Yes. Ductile iron, nodular iron, spheroidal graphite (SG) iron and spheroidal graphite cast iron are names for the same material family. The graphite forms round nodules, which gives the iron measurable elongation.
Is ductile iron the same as cast iron?
Ductile iron is a type of cast iron. In everyday RFQs “cast iron” often means grey (gray) iron, so a drawing that only says “cast iron” is incomplete: name the family, the grade and the standard.
Which ductile iron grade should I start with?
Common starting points: QT400-15 (EN-GJS-400-15, A536 60-40-18) where elongation and impact toughness matter most; QT450-10 (EN-GJS-450-10, A536 65-45-12) for general hubs and brackets; QT500-7 (EN-GJS-500-7, A536 80-55-06) for higher strength; QT600-3 (EN-GJS-600-3) for higher strength with low elongation. The designer chooses the grade.
Can ductile iron castings be weld repaired?
Only if your specification allows it. State in the RFQ whether any repair of the castings is permitted, and by which method, so it can be confirmed before quotation.
Are your ductile iron parts sand castings?
Yes. Ductile iron parts are produced by sand casting. The pattern, moulding and cores are planned from your drawing, and machining, finish and inspection are quoted to the agreed supply condition.
Can you supply ductile iron castings machined?
Yes. Castings can be supplied raw or CNC-machined on the bores, faces, holes and threads shown on the drawing. JK Casting machines castings it supplies; machining-only orders for parts cast elsewhere are outside the supply scope.
Send your ductile iron drawing for review.
Include the full grade and standard, the quantity and the raw or machined supply condition. JK Casting will not substitute grey iron for ductile iron, or the reverse, without your approval.