Brinell Hardness（HBS）and Rockwell hardness(HRC) are a typical reference standard for cast iron and ductile iron products.However,almost all customers prefer Brinell Hardness（HBS）as the inspection standard for casting hardness.

The reasons for the preferred Brinell Hardness（HBS） tester for casting hardness testing are as follows:

1. Castings usually has uneven inside structure and large crystal grain size,hardness is different on different tiny regions and different points.However,Brinell hardness tester has larger pressure head size and larger indentation area,Brinell hardness tester can measure the average hardness in the region,so using Brinell hardness tester has higher accuracy and authority.

2. Tensile strength is the main mechanical property of castings,almost all castings standards require tensile strength. However,the values of Brinell hardness and tensile strength of castings can be converted to each other. The formula is as follows:

σb=1.82（HB）1.85

Some American customers will choose ASTM A48-92 and ASTM A159-88 as a hardness test standard for Grey cast iron,ASTM A536-84 and ASTM A439-89 as a hardness test standard for Ductile iron.

Rockwell hardness tester is also mainly used for castings hardness testing,it is more suitable for castings with finer crystal grain and smaller area.However,our hardness testers should choose different areas as a measuring point,multiple measurements to take the average.

Rockwell hardness tester has the following advantages: fast, easy to test, small indentation areas, also can directly test the finished casting. Brinell hardness and Rockwell hardness conversion formula as follows:1 HRC≈1/10 HB.

If you have high requirements for casting hardness,our castings need the better abrasive resistance,before production in our foundry,we need add one hardness requirement for your products,so the foundry can adjust the chemical composition to increase the hardness.

The following list is for the typical Brinell Hardness range for the main grades of ductile iron and gray cast iron.

Reasonable range of Brinell hardness for Ductile iron castings:

Reasonable range of Brinell hardness for Gray iron castings:

This article is from our Dandong Iron Casting Group Foundry's  Gary Cast iron Brinell Hardness,Ductile iron Rockwell hardness and Cast Iron