Grey cast iron: HT250,EN-GJL-250, CAST IRON GG25

HT250 is a high material grade of grey cast iron in China standard, it is also named as Europe standard EN-GJL-250 EN 1561, GG25 in standard DIN 1691 by Germany and Austria. 

Chemical Composition

The normal chemical composition should be C = 2.8-3.3, Si = 1.2-1.7, Mn = 0.8-1.2, P ≤ 0.15, S ≤ 0.12.

Please notice, the chemical composition can not be taken as material quality inspection standard. In all standards, the chemical composition is just for reference. The grey iron foundries could adjust their composition according to their own production condition and experience, as long as they could guarantee to meet the mechanical properties, which is the only inspection standard.

However, if the iron castings need to meet special application, so will require the specific chemical composition, then the buyers should denote this requirement clearly, and the grey iron foundries should take it as the quality standard.

Mechanical Properties

Tensile Strength ≥ 250 Mpa
Yield Strength: No Requirement.
Hardness Range: 190 to 240 BH

Only the tensile strength is the quality inspection standard. Other mechanical properties are only for reference unless the buyers have particular requirements.

HT250, EN-GJL-250, GG25 Grey Iron Castings

This grade has comparatively high tensile strength, and will not need additional heat treatment, so its production cost is kept low. However, its hardness is comparatively high, so as for the castings parts with thin wall thickness, the hardness for some positions will be very high, over 200 HB, therefore, will cause difficulty to machining, especially to drilling and milling. 

Moreover, will cause the casting parts more crispy. So, if the lower tensile strength could meet your use, better to choose lower grade HT200, EN-GJL-200, GG20 or HT150....

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