I tried to understand your explanation from the mill but it seems hard to visualize.
And we still do not understand why induction hardening is carried out on medium
carbon steel like AISI 4140 and AISI 4340. These grades are easily quenched in liquid
medium (usually oil or polymer) to achieve good martensite structure; then tempered
to reduce brittleness and stresses, and to achieve the strength and toughness.
Does induction hardening give such tempered micro structure?
Induction hardening is a case-hardening process or surface hardening. It is done after
the bars have gone through the Q &T process to achieve the said structure.
Can you send us a picture of this “bar crash head to end of roller bench .. “?
Even if these bars are guarantee the mechanical properties, how much do we need to
cut off to make sure that the balance bars have no internal crack?
We apologies for such lengthy discussion as we do not have such experience in our history
of dealing with Q&T bars. Hope we can have a satisfactory answer.