The cross-reference is approximate
The cross-reference below is approximate. The standards use different test bars, units and minimum values. The standard named on your drawing always governs, and any substitution needs your written approval.
How to read the grade names
- HT250 / EN-GJL-250 / FC250: minimum tensile strength 250 MPa.
- ГОСТ 1412 СЧ25: minimum tensile strength 250 MPa (25 kgf/mm²). The number in a СЧ grade is the tensile strength in MPa divided by 10.
- ASTM A48 Class 35: minimum tensile strength 35 ksi (241 MPa). A letter after the class (A, B, C or S) names the test bar, for example Class 35B.
- GG25: the former German DIN name, still common on older drawings. It was replaced by EN-GJL-250.
Gray iron grades are defined by tensile strength. None of these standards sets a minimum elongation for gray iron.
Gray iron cross-reference chart
Scroll sideways to compare standards
| GB/T 9439 (China) | ASTM A48 (USA) | EN 1561 (Europe) | Old DIN | ГОСТ 1412 (Russia) | JIS G5501 (Japan) | Min. tensile |
|---|---|---|---|---|---|---|
| HT200 | Class 30 (207 MPa) | EN-GJL-200 (200–300 MPa) | GG20 | СЧ20 | FC200 | 200 MPa (A48: 207 MPa) |
| HT250 | Class 35 (241 MPa) | EN-GJL-250 (250–350 MPa) | GG25 | СЧ25 | FC250 | 250 MPa (A48: 241 MPa) |
| HT300 | Class 40 (276 MPa) | EN-GJL-300 (300–400 MPa) | GG30 | СЧ30 | FC300 | 300 MPa (A48: 276 MPa) |
Values are minimum tensile strengths on separately cast test bars. GB/T 9439 and EN 1561 use a 30 mm diameter bar. EN 1561 states each grade as a range from the minimum to the minimum plus 100 MPa, and ГОСТ 1412 does not allow more than 100 MPa above the minimum unless the casting documents say otherwise.
ASTM A48 classes are in ksi (Class 30 = 30 ksi = 207 MPa). The test bar (A, B or C: 22.4, 30.5 or 50.8 mm) is chosen from the controlling wall thickness of the casting, so the test basis is not the same as the 30 mm bar. The ASTM column is the nearest class, not an equal value: Class 35 (241 MPa) and Class 40 (276 MPa) are below the 250 and 300 MPa of HT250 and HT300.
Strength in the casting itself falls as the wall gets thicker. GB/T 9439 and EN 1561 list lower expected values for thicker walls, so state the critical section when strength matters.
Why gray iron has no elongation value
In gray iron the graphite forms flakes. The flakes give good machinability and vibration damping but very little elongation, which is why grades are set by tensile strength alone. Ductile iron has round graphite nodules and is specified with elongation as well.
Gray iron: flake graphite
Ductile iron: spheroidal (nodular) graphite
Which grade to choose
| If the part needs… | Usually start with | Why |
|---|---|---|
| Covers, bases and lightly loaded housings | HT200 / EN-GJL-200 / Class 30 | Easiest to cast and machine |
| Machine housings, bearing housings and gearbox parts | HT250 / EN-GJL-250 / Class 35 | Common general-engineering grade |
| Higher strength or wear resistance | HT300 / EN-GJL-300 / Class 40 | Higher strength, harder to machine |
| Elongation, impact strength or shock loads | Ductile iron instead of gray iron | Gray iron has no elongation requirement |
These are starting points, not design rules. The final grade depends on loads, section thickness and the inspection the drawing requires.
What to put on the drawing or RFQ
- The full designation and the standard, for example “EN-GJL-250 per EN 1561”, “HT250 GB/T 9439” or “ASTM A48 Class 35B”. “Cast iron” on its own is not enough to quote against.
- How strength is verified: a tensile test on a separately cast bar, a cast-on bar or a sample cut from the casting. For ASTM A48, give the bar letter.
- A hardness range, if machining or wear matters. EN 1561 and GB/T 9439 also have grades defined by hardness instead of tensile strength.
- Inspection documents: for example an EN 10204 3.1 material certificate with the chemical composition and test results.
- Whether equivalents are acceptable. If your drawing uses ASTM and you will accept HT250 or EN-GJL-250, say so in writing.
How JK Casting supplies gray iron
JK Casting makes gray iron castings to customer drawings in Gaomi, Shandong, China. Regular gray iron grades are HT200, HT250 and HT300 and their GG, EN-GJL and ASTM A48 equivalents. Gray iron parts are produced by sand casting and supplied raw or CNC-machined to the drawing: turning, milling, boring and drilling. The drawing’s standard governs, and material records such as EN 10204 3.1 certificates are provided when agreed for the order.
Related pages: Gray and ductile iron castings · Ductile iron grades chart · Material selection · Send a drawing for quotation
Frequently asked questions
Is HT250 the same as ASTM A48 Class 35?
They are close but not identical. HT250 requires 250 MPa minimum tensile strength on a 30 mm bar; Class 35 requires 35 ksi (241 MPa) on a bar chosen by wall thickness. If the part needs 250 MPa, keep that standard on the drawing or state the minimum.
What is GG25 today?
GG25 is the former German DIN designation. Its current European name is EN-GJL-250. The Chinese, Russian and Japanese grades with the same 250 MPa minimum are HT250, СЧ25 and FC250.
Does gray iron have an elongation requirement?
No. Gray iron grades are set by minimum tensile strength, or by hardness for hardness grades. If the part needs elongation or impact strength, ductile iron is usually the better choice.
What is the Russian equivalent of HT200?
ГОСТ 1412 СЧ20 has the same 200 MPa minimum tensile strength. Both standards test it on a separately cast bar.