Comparison of free-cutting hot rolled high strength steel for connecting rod

The foreign and domestic C70S6 steels were analyzed by metallographic examination and non-metallic inclusion comparison. The results show that the compactness of foreign materials was good, while the dendrite segregation of domestic materials was serious, and the banded structure was more serious than that of foreign materials. The sulfide morphology of foreign materials was mainly short rod spindle, which was beneficial to improve the cutting performance, while the sulfide of domestic materials was mainly elongated. Domestic materials contained larger particles of non-metallic inclusions, its molten steel purity was worse than foreign materials.