Selective generation of local ferromagnetism in austenitic stainless steel using nanoindentation

Abstract

Periodic arrays of magnetic structures with micrometrer and submicrometer lateral sizes have been prepared at the surface of an austenitic stainless steel by means of local deformation using a nanoindenter. This method takes advantage of the phase transformation (from nonmagnetic fcc austenite to ferromagnetic bct martensite) which occurs in this material upon plastic deformation. The local character of the induced ferromagnetism is confirmed by magneto-optical Kerr effect measurements together with magnetic force microscopy imaging. The generated ferromagnetism can be subsequently erased by subjecting the deformed steel to annealing processes at temperatures above the reverse, martensite-to-austenite, phase transformation temperature.

Effect of Hydrogen and Strain-Induced Martensite on Mechanical Properties of AISI 304 Stainless Steel

“…After calibrating the feritscope using the standard sample, the average amount of the formed SIM was measured either ex situ within 1 mm of the fracture surface five times, or in situ at the center of the gauge section during tensile testing. For the sample deformed to the same strain, the volume fraction and distribution of SIM on the surface were measured using the MFM by applying the distinct magnetic properties of nonmagnetic austenite (γ) and ferromagnetic α 1 [17][18][19]. Images of MFM and atomic force microscope (AFM, Park systems, Suwon, Korea) were obtained in air using a scanning probe microscope (Nanoscope IIIa) in the tapping/lift mode with a lift height of 100 nm.…”

Martensitic transformation in SUS 316LN austenitic stainless steel at RT

“…This is because alloying elements like Ni, Mn, N and Cu considerably stabilize the austenite structure while the Cr promotes α ′ structure. There are few studies on the deformation induced α ′ in 316 stainless steel [15][16][17][18][19][20]. For instance, tensile testing [15] and selective generation of local ferromagnetism by nanoindentation [19] have been reported for the type 316 stainless steel.…”

Tuneable magnetic patterning of paramagnetic Fe60Al40 (at. %) by consecutive ion irradiation through pre-lithographed shadow masks

“…depend on the amount of structural disorder. In turn, paramagnetic austenitic stainless steel transforms to FM martensite or FM expanded austenite under the action of mechanical stress 25 or N ion irradiation, 26,27 respectively. It has been recently shown that focused ion beam (FIB) and ion irradiation through prelithographed poly(methyl methacrylate) (PMMA) masks can cause the necessary atomic disorder to induce ferromagnetism in the Fe 60 Al 40 alloy.…”

“…This occurs in some intermetallic alloys and austenitic stainless steels, which undergo structural transformations (from nonmagnetic to FM phases) when they become structurally disordered. [16][17][18][19][20][21][22][23][24][25][26][27] Disorder-induced magnetism has been actually reported in a number of transition-metal (TM) 21 CoAl, 22 or CoGa. 23 In these systems, the magnetism can be understood in terms of the local environment model, where the magnetic moment of a given TM atom depends on the number of nearest neighbor TM atoms.…”