SU1396024A1 - Method of radiographic testing of plasticity resource of martensite-ageing steels - Google Patents

Abstract

The invention relates to the field of physical materials science and can be used in determining the mechanical characteristics of steels in laboratory and factory conditions in various industrial fields. The goal is to improve the accuracy of plasticity resource control and determine the tensile strength of steels whose structure is formed during quenching from the intercritical temperature range. Due to the non-monotonous change in p (the parameters of martensite-aging steels and the magnitude of the maximum uniform plastic deformation depending on temperature, their unique mutual correlation cannot be used to find the plasticity resource. Therefore, to determine the plasticity resource and strength from the a series of standards are made of the controlled steel and the lattice period and the width of the interference for the matrix phase and austenite are measured on them, and then the same parameters and the amount of austenite - in a controlled sample. From the curves of the interrelationship of the half-width and the period of the matrix phase and austenite, the type of austenite is present (reverse-HbDi or residual), after which the plasticity resource of the steel and the ultimate strength are found from the corresponding curves of these values of the residual or reverse austeite, 5 il. 1 tab. S (L with with so of about about 4

Description

The invention relates to the physical science of materials and can be used in determining the mechanical characteristics of steel in laboratory and factory conditions in various industrial fields.

The purpose of the invention is to improve the accuracy of control of the ductility resource and to determine the tensile strength of steels whose structure is formed during quenching from the intercritical temperature range,

: FIG. 1 shows a graph of the change; the half-widths of the diffraction line of the matrix phase and plasticity resource maximum uniform plastic deformation ρ from the quenching temperature; in fig. 2 is a graph of the formation of the inverse and residual austenite in X12H10M1 martensitic-aging steel at temperatures Å l. Of transformation, as well as the change in the martensitic point Mts | C; FIG. 3 is a graph of the dependence of the plasticity resource rI of the predex strength 66 on the amount of reverse (-) and residual (, -) austenite of martensitic-aging steel H18K9M.5T; in fig. 4 and 5 - interrelation of structural parameters of the parameters (matrix phase and a, 4ij () for- trusts austenit in steel H18K9M5T in the case of inverse (-) and residual (). Autetenite.

The proposed method is based on the results of a detailed study of the structural changes in the martensitic-aging steels depending on the heat treatment conditions (Fig. 1), which showed that the reverse and residual austenite in accordance with the different formation mechanism is characterized by a different, but specific for each of them the width of the (l, l) and (/ 5d) X-ray interference with the lattice constant of the matrix phase (aj and austenite (a) formed during quenching).

The different interrelationships of Lf (fij and a. (F, (/ bd) for reverse and residual austenite (Figs 4 and 5) are due to the peculiarities of the formation of these phases. Reverse austedagt is formed in the structure of the overgrown martensite (left branch of the curve, fig. 2). As the amount of fd of inverse austenite increases, the width of the x-ray interference (; B,) and ((1) and the lattice constant

a, a, both martensite and reverse austenite (Fig. 4 and 5).

The residual austenite (right branch of the curve, Fig. 2) is retained during quenching in the structure of cooling martensite and, like cooling cooling, is characterized by a sharp increase in the level of variation of the width of the x-ray interference. At the same time, with an increase in the amount of residual austenite f4, its crystalline constant f

lattice a increases

and 5), and the lattice constant of martensite a decreases (Figs. 4 and 5). For martensite cooling, a weak dependence of / 3 „on Gd is characteristic. The logical nature of the connection (h) and hell i / j (p) for reverse and residual austenite is confirmed by electron microscopic analysis, revealing its different microstructure of austenite of various types.

In this connection, in order to separate the inverse and residual austenite, a joint analysis of the change in the width of the x-ray interference | 5 and the lattice parameters of (a) the matrix phase and austenite is necessary.

To improve the accuracy of determining the type of austenite, one should use the fbj interrelation at f ;, 20% and the interrelation a v, (with.

As an example of the method implementation, the results of monitoring the plasticity resource of sheet semi-finished products from martensitic aging steel H18K9M5J hardened from the intercritical temperature range are given. According to the proposed method, the amount of austenite in the samples was measured f. and structural parameters of the matrix phase of the p „a miirin x-ray interference and the lattice constant and austenite of the crystal lattice,%,. For a set of standards, the changes in the structural parameters of the studied steel were determined (f, (/ 1д) and а „tf / ibj for the case of inverse and residual austenite.

Of the 1 2 studied prefabricated, you found 4 with pairs of the same amount of austenite. The table for the identified amounts determines 1 and the numerical values of the corresponding parameters of martensite and austenite. When comparing them with staged values, it was established that in semi-finished products

1 and 3 type of austenite reverse, and in

2 and 4 - residual. Having determined the type of austenite found, they found the desired

steels are quenched from different temperatures from the critical range, obtaining a two-phase martensitic-austenitic structure with a reverse and / or initial value of the plasticity resource p (maximal austenite, measured by their maximum uniform plastic deformation of the material, when exceeded, loss of shape memory develops and the destruction of the product) strength 6g (4ig. 3) of the dependences of these parameters on the amount of reverse or residual austenite obtained for a set of standards from the steel under study ,.

sura plasticity fp and ultimate strength & g, the amount of reverse and / or residual

Q of austenite f, width / s of one of its diffraction lines, and period of austenite lattice hell and matrix phase of martensite) and then build dependencies p V, (ffl), 69) a lf // J),

15 - / m Rm) and inverse and residual austenite, the amount of austenite f for the sample from the controlled material, f, and structural parameters

15 - / m Rm) and inverse and residual austenite, the amount of austenite f for the sample from the controlled material, f, and structural parameters

Claims (1)

Invention Formula The method of radiographic monitoring of the plasticity resource of marketable and aging steels, including the austenite type: reverse or residual, The standard irradiation of the standards and the comparing-measured value of a with sample x-ray / reference values ja. obtained by registration of their diffraction patterns and of the dependence a (C (Pd Y for found the definition of the width of the x-ray values of p, and at fy, 20% of the matrix phase j от 25 D type of austenite, compared with those measured by with the values of hell, with its reference value of increasing the accuracy of plasticity resource control and determining the limits, obtained from the dependence of the found value of p ,, and determine the average and the reference dependencies of p (fy) and ,, ( f) for the type and amount of austenite found in Gd B sample, strength of steel, whose structure is formed during quenching from the intercritical temperature range (Asu., - AC}), standards from the controlled steels are quenched from different temperatures from the critical range, obtaining a two-phase martensitic-austenitic structure with reverse and / or reinforced plasticity fp and tensile strength & g, the amount of reverse and / or residual Q of austenite f, width / s of one of its diffraction lines, and period of austenite lattice hell and matrix phase of martensite) and then build dependencies p V, (ffl), 69) a lf // J), 15 - / m Rm) and inverse and residual austenite, the amount of austenite f for the sample from the controlled material, f, and structural parameters „Austenite type: reverse or residual hell, with its reference sign derived from the dependence of the found value of p ,, and determine Cp and B from the reference dependencies p (fy) and ,, (f) for the type and amount of austenite found in Gd B sample, Determination of the mechanical properties of steel 50G in 60 fiO 20 A, yuuu / I V ABOUT   5W 620 660 7yO G.S Fig 2 6/7,% ABOUT d / m g in M, OSP a / rrat / ff. 0 . "..- 6 g mffc 1900 nao 7500 GZOO Guo 2.867 W 1uIff2226 fie, so 0.% about, 3.595 J. 3.5fff fffn26-SO JSA -fO.pa Fig 5. -.u .... "