Quantitative relationship between the cast matrix structure grain size, martensite dispersity, and strength of hardened cast iron

Conclusions

• 1. The dimensions of the cast matrix structure grain and of the graphite globules have the governing influence on the thicknesses of the hardened layer and of the transition zone, and also on the degree of dispersion of the martensite, and, consequently, on the mechanical properties of the iron.

• 2. We have established a quantitative connection between the dimension of the cast structure grain, the dimension of the graphite globules, the degree of dispersion of the martensite, and the strength (σ_u).

• 3. We have obtained regression equations that make it possible to evaluate the influence of the dimensions of the grain of the cast structure of the iron and the dimensions of the graphite globules, and the degree of dispersion of the martensite on the strength of iron parts that are inductively hardened. The accuracy of the prediction using these equations is 1.5–2.0 times higher than the accuracy obtained using the average value from the tests for the entire lot of specimens.