Abstract��During the mechanical property testing of the hot rolled round steel of SCM420H alloy steel produced in a steel mill�� it was found that there were big differences in the elongation and shrinkage of two tensile samples. The macro and micro analysis of the tensile fracture of SCM420H alloy steel were studied by means of electron microscope and optical microscope. It��s a typical cup cone-shaped fracture and the crack source was near the center position. A large-sized calcium aluminate inclusion surrounded by many small particles was found at the source of the crack. The experimental results showed that the calcium aluminate nonmetallic inclusions at the crack source of the tensile sample were the main reasons for the lower elongation and the lower shrinkage of the SCM420H tensile sample.
2018, Vol. 36 
