Many important complex parts in mechanical equipment often use casting of steel as they are solid and durable. The rough castings need to be accepted according to the requirements of the steel technical terms and conditions. Mechanical performance is one of the major projects for acceptance of the casting of steel quality. General casting of steel need to check the tensile strength. They can’t get into the next procedure to be processed if they are not qualified.

During tensile test, there are conditions that worker can not measure the tensile strength due to the defects of samples. In these conditions the rough casting parts can not turn in time sequence which will affect the production efficiency. In order to solve this problem, it is necessary to research the conversion relationship between the strength and hardness of casting of steel. Although there are national standards for the casting of steel, in the practical application, the error between the hardness and strength of the standard conversion and the actual value in the real production process is not small. So in the casting production, it is significant to make the modification by related test and to meet the needs of the industrial and mining enterprises for actual production.