Magnetic Anisotropy of Hard Milled Surfaces

Abstract

Grinding operations are sometimes replaced with hard turning or milling cycles. Mechanism of chip separation during grinding and the corresponding surface integrity remarkably differs from hard turning or milling. For this reason, this paper deals with application of Barkhausen noise for evaluation of surface anisotropy after hard milling. Experiments were carried out on bearing steel 100CrMn6 hardened on 45, 55, 62 HRC and one series without heat treatment. The analysis contains comparison of RMS values for the different hardness and tool wear after hard milling and also discusses the specific mechanism of BW motion in the case of cyclic magnetization.

Non homogeneity of surface integrity after hard milling of high tempered bearing steel

“…It is also worth to mention that character of WL initiated by hard milling and grinding is different. Thin WL after hard milling increases BN due to preferential orientation of matrix and corresponding BWs alignment into the direction of measurement [9]. As soon as thickness of WL after hard milling increases (along with more developed VB) BN decreases due to increasing volume of retained austenite as a non ferromagnetic feature strongly hindering BWs motion.…”

“…It is also worth to mention that the ratio between WL and HAZ thickness after hard machining is much higher as opposed to grinding [5,7,8]. Hard milling surfaces were already investigated and reported [5,7,8,9]. However significant aspect associated with non homogenity due to missing full contact between milling cutter and sample has not been discussed yet.…”