Influence of microstructural parameters of indefinite chill alloys on flexural strength and Young's modulus

The investigated indefinite chill materials are designed for highest wear
resistances for surface-critical applications in hot strip mills. The microstructure
consists of tempered martensite together with cementite and
MC carbides as well as a certain amount of graphite in different morphologies.
These alloys have very high hardness values and a poor
toughness which makes it rather difficult to measure the mechanical
properties with standard testing methods. These materials were successfully
tested with the 4-point bending method and reliable and comprehensible
values for the flexural strength and the Young’s modulus
were generated. A clear correlation between those values and the total
amount of carbides and graphite was found. Also, both values are dependent
from the shape of the graphite precipitations. The investigations
prove that the 4-point bending test is a feasible method to test the
mechanical properties of indefinite chill alloys.