Effect of MnS Inclusions on Fracture Layering of Low Alloy Steel
ZHU Haoxue
Abstract：Analyze the fracture delamination problem in the room-temperature transverse tensile test of 420 MPa grade low-alloy steel plates,paper adopts multi-dimensional technologies such as fracture morphology observation,non-metallic inclusion detection,metallographic structure analysis,scanning electron microscope(SEM)inspection,and energy dispersive spectroscopy(EDS)inspection to systematically explore the macro-morphology and microstructural characteristics of the samples,and clarify the causes of delamination and key influencing factors.The results show that the pearlite composition segregation and type A MnS strip inclusions in the core of the steel plate are the core causes of delamination.The composition segregation forms a mechanical weak zone in the core,and the MnS inclusions split the matrix and cause local stress concentration.Under the tensile load,cracks initiate and propagate in the stress concentration area,leading to delamination.The chemical composition and overall mechanical properties of all samples meet the GB/T 1591-2018 standard,and delamination is caused by local defects.In view of causes,measures such as improving purity of molten steel,optimizing continuous casting process with low superheat pouring,and adjusting controlled rolling and controlled cooling parameters are proposed,which can effectively reduce the occurrence rate of delamination defects.
Keywords：high-strength low-alloy steeltensile fracture delaminationcomposition segregationMnS inclusionprocess optimization
Publication Date：2025-08-20
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：4( 26-29 )