Now with the prevalence of covers, however in the market, it's more and more types, cast iron covers, ductile iron covers, composite covers, concrete covers. Which cast iron covers and ductile iron covers are very similar to the appearance, just from the surface point of view can not be identified, in fact, different materials expressed between the effect is not the same, then this requires us to be able to clear on the purchase Point important to identify matters, we specifically to understand the specific.

(1) percussion covers: ductile iron covers issued sound like a knock on the sound of carbon steel. The percussion sound of the gray iron cover sounds boring.

(2) from the fracture point of view: the former fracture grain is very small, dark gray. And gray iron cover at the fracture of the grain is relatively large, gray.

(3) from the refining method: ductile iron covers are in the refining of iron in the iron in the inoculant and the nodularizer to disperse the graphite flocculent into a spherical shape, to reduce the ferrite fragmentation , Increase the strength, improve performance to achieve.

(4) gray iron cover in the treatment of refining without adding any auxiliary materials, directly to the iron into the molten iron, and then cast into a well cover. The former in the rule of time to join the ball agent, rare earth magnesium and other metal alloy.

(5) Ductile iron covers have high strength and toughness, so it is about 30% lighter than similar gray iron covers.

(6) is also a ductile iron products, different rate of ball, the quality is different, the price is also very different.