Use of the Superplasticity Phenomenon of Steel for "Internal" Magnetic Correcting a Product

Abstract

The results of the course of martensite transformation in steel under the action of the magnetic field are presented. These results indicate that the formation of stress-assisted martensite in the temperature interval Md-Ms (where superplasticity was observed) is possible. It was found that during hardening of steel products in magnetic field, martensite can be formed not only below Ms, but higher than this point (in the temperature range). The significant structural transformations and steel properties improvement under thermal treatment in a magnetic field depend on the catalytic effect of a field on the transformation development. This effect occurs when the initial phase is paramagnetic, and the product of the transformation is ferromagnetic. Stress-assisted martensite and cooling-induced martensite are formed in the superplastic temperature range of the austenite. This makes it possible for the undeformation hardening of steel products in a magnetic field. The undeformation hardening is caused by a magnetic field holding the product and the formation of martensitic structure oriented predominantly towards the magnetic field vector.

The Technology of Distortion-Free Quenching in a Magnetic Field of Thin-Walled Details of the Ring Form

“…Exposure to a magnetic field allows, to some extent, to control phase transformations during heat treatment [6][7][8][9][10][11]. Methods and devices for thermal processing in a magnetic field (HTMF) have industrial introduction and are described in a number of works [12,13]. For example, we considered a device for reducing distortion when quenching thin rods in a magnetic field [13].…”

“…The possibilities of heat treatment in a magnetic field are due to the fact that austenite microvolumes with a near spin order [14,16] perceive the energy of an external magnetic field through magnetostriction. Under conditions of superplastic austenite [9,12], magnetostriction stresses can change the fields of elastic forces in the microvolumes of the atomic lattice and thereby reduce the energy barrier for the formation of a germinal center of critical size [7,17,18]. Structural stresses are the result of phase hardening during the martensitic transformation due to the difference in the specific volumes of martensite ∆V and austenite, with ∆V = VМ -VА > 0.…”

“…The device was used for heat treatment of disk cutters made of HS6-5-2 steel with a diameter up to 280 mm and was a double coaxial electromagnet for exciting a permanent magnetic field with a strength of 1600 kA/m. The impact of the magnetic field allowed the deformation-free hardening of products due to the "internal" straightening [12] of the product and the reduction of the level of structural stresses due to the decomposition of martensite during the quenching cooling. As a result, it was found that this measure is economically feasible, since the use of magnetic hardening eliminates the need for hardening under pressure, increases the operational durability of the cutters by 1.6÷1.8 times and reduces the cutter consumption by 1000 machined parts from 0.12 to 0.081 pieces.…”

Практика Омагничивания В Постоянном Магнитном Поле Термически Обработанных Быстрорежущих Сталей

“…Также известен ряд работ, показывающих влияние магнитных полей на протекание фазовых превращений в сталях и сплавах [3][4][5][6][7][8][9][10].…”

Распад Остаточного Аустенита В Стали У12 При Обработке В Магнитном Поле

“…Отпуск -это процесс, который в конечном итоге влияет на структуру и свойства закаленной стали. Влияние внешнего воздействия магнитного поля на протекание различных фазовых превращений проявляется в изменении фазового состава, структуры и свойств конечного продукта превращения [1][2][3][4][5][6][7][8][9]. Необходимо учитывать изменения в структуре закаленной стали, вызванные действием магнитного поля во время охлаждения и отпуска, поскольку они во многом определяют результаты термообработки, которая представляет собой комбинацию закалки в магнитном поле с отпуском без поля и в поле.…”