What Are the Standards and Methods for Iron Foundry to Accept and Control the Hardness of Gray Cast Iron Castings

The mechanical properties of cast iron are related to the structure of the matrix and the morphology of graphite, and the matrix structure has a certain influence on the mechanical properties of gray cast iron. For cast iron foundries, gray iron castings have many benefits such as good casting performance, shock absorption, wear resistance and cutting performance, as well as low notch sensitivity.

Gray iron castings have certain acceptance criteria after pouring, and its acceptance criteria are mainly based on the requirements of customers, generally the following acceptance criteria:

1. Cast iron casting manufacturers should test whether the chemical composition of the castings is standard;

2. Whether the mechanical properties of the casting are standard, tensile strength and hardness, etc.;

3. Whether the metallographic of the casting is standard, such as the content of carbide, the content of pearlite, the length of graphite, etc.;

4. Size requirements of castings;

5. Performance requirements of castings, such as leakage and suppression, etc.;

Sometimes the gray iron castings cast by cast iron foundries are relatively hard, and there are several reasons for this:

1. If the carbon content is low, then the manufacturer needs to appropriately increase the carbon content to improve;

2. The proportion of scrap steel in the bottom material is high, and the cast iron casting manufacturer can solve the problem by increasing the proportion of pig iron or return material;

3. Whether the alloying elements are too high, such as manganese and chromium, in the case that the strength meets the process and there is a large margin, the cast iron casting manufacturer can appropriately reduce the content of alloying elements;

4. Is the amount of inoculant too small, if it is too little, it will make the thin wall not get good gestation and appear hard or even white.Cast iron casting manufacturers pay attention to the above problems, then the hardness of gray iron castings will be very well controlled.