Study on Strength and Toughness Testing of 45 Steel Based on Continuous Ball Indentation Method

In order to study the testing and evaluation of material strength and toughness of in-service equipment, the continuous ball indentation method is used to obtain the yield strength, tensile strength and fracture toughness of 45 steel, which is commonly used in engineering. The reliability of the method was verified by comparing the results with those of the conventional mechanical property test. By studying the relationship between the plastic work produced by the downward pressure of the ball head and the impact crack initiation energy and fracture toughness, the impact toughness estimation method based on instrumented ball indentation test technology is established. The results show that the deviations between the yield strength and tensile strength obtained by the continuous ball indentation method and the actual results are less than 10%, and the deviation between the fracture toughness value and the experimental result is 12.3%. The calculated results are all within the acceptable deviations of experimental values. Based on the correlation formula between fracture toughness and impact toughness established by continuous ball indentation technique, the predicted impact toughness results are in good agreement with the values from the instrumented impact test. This provides an effective method for rapid evaluation of toughness of in-service equipment materials.