abstract = "In this paper, machinability influences from the start
to end of final product production in a steel plant
were analyzed, including chemical composition,
deoxidizing agents and casting parameters, which
drastically influence the macrostructure and
segregation (i.e., chemical nonhomogeneity) of
continuously cast and subsequently rolled material. The
data (seven parameters from secondary metallurgy, four
parameters from the casting process and the content of
ten chemical elements) from the serial production of
calcium-treated steel grades (254 batches of 25
different steel grades from January 2018 to March 2020)
were used for predicting machinability. Machinability
was determined based on ISO 3685:1993, where the
machinability of each individual batch is represented
as the cutting speed and the tool is worn out within
fifteen minutes. For the prediction of these cutting
speeds, linear regression and genetic programming were
used. Out of 25 analyzed steel grades, 20MnV6 steel
grade was the most problematic and also the most often
produced. Out of 57 produced batches of 20MnVS6 steel,
23 batches had nonconforming machinability. Based on
the modeling results, the steel making process was
optimized. Consequently, 40 additional batches of
20MnV6 (from March 2020 to July 2020) were subsequently
produced based on an optimized steelmaking process. In
all 40 cases, the required machinability was achieved
without changing other properties required by the
customers.",
notes = "STORE STEEL, d.o.o., Research and Development, 3220
Store, Slovenia