Research on the generation mechanism of short rod-shaped magnetic traces in the new generation of aviation gear steel 15Cr14Co12Mo5Ni
LIU Chunjiang
WANG Gengjie
JIANG Tao
LIU Changkui
LIU Mingyue
WANG Rongchao
ZHANG Hongbin
Abstract：[Objective]15Cr14Co12Mo5Ni alloy is a new type of low-carbon high-alloy steel featuring high strength,high temperature resistance and excellent wear resistance,which is widely adopted in high-end fields such as aerospace and automotive transmissions.Magnetic particle inspection plays a vital role in quality inspection of components made from this alloy.However,the occurrence of short rod-shaped magnetic traces frequently interferes with inspection results.Investigating the formation mechanism of short rod-shaped magnetic traces and analyzing their correlations with the internal microstructure,carbide distribution and forging process of the alloy can provide basis for optimizing forging procedures,controlling grain size,restraining excessive development of dislocation slip bands and reducing interference from magnetic traces.[Methods]Specimens with and without magnetic traces on the shaft bore of alloy gears were selected.Combined with magnetic particle inspection,scanning electron microscopy,metallographic observation and energy dispersive spectroscopy analysis,comparative research on morphological characteristics of magnetic traces,carbide compositions and grain structure differences was carried out from both macroscopic and microscopic perspectives.[Results]Macroscopic and microscopic analyses reveal that the formation of short rod-shaped magnetic traces is closely associated with the clustered distribution of Cr-Mo carbides inside the alloy.Such carbides generate magnetic leakage fields by altering local magnetic permeability,leading to the accumulation of magnetic particles.Further research clarifies the microstructure evolution chain for short rod-shaped magnetic traces,which can be summarized as:coarse grains → dislocation slip bands → Cr/Mo enrichment → directional precipitation along interfaces →carbide banding → magnetic permeability gradient → short rod-shaped magnetic traces.
Keywords：Short rod-shaped magnetic traceMagnetic permeability gradientCr-Mo based carbideDislocation slip bandMicrostructure evolution chainForging process
Publication Date：2026-08-15
Online Publishing Date：2026-09-12(First online date of this platform, not the publication date of the document)
Pages：7( 185-191 )