SU985087A1 - Method of producing articles from construction steels - Google Patents

Description

(54) METHOD OF MANUFACTURING HARDENING FROM STRUCTURAL STEELS

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The image refers to ferrous metallurgy and can be used to make responsible high-strength products.

; A known method of making rolled profiles, including hot rolling, quenching in the process of forming by bending C13.

The disadvantages of this method are as follows: 1 and the complexity of the technological process, cracking of the product during quenching, and, moreover, a tendency to brittle fracture.

A known method of manufacturing bimetal-} 5 Pieces, including heating the workpiece to the temperature of plastic deformation of the cladding layer, pre-stamping, cooling to tektera-, tours of the relative stability of the austenite of the cladding layer, final stamping, tempering from the stamping temperature and tempering Base Metal02 .J.

The disadvantage of this method is to immediately give the product its final shape and final properties, which is unacceptable in a number of cases, since it is necessary to carry out mechanical processing.

A known method of manufacturing products from metals and alloys of high strength, which involves heating to the austenization temperature, holding and forming a scientific research institute by bending with this tetrapure, quenching and tapping f 3 J.

However, in the existing method, heating to the austenitic region is aimed solely at reducing the deformation resistance. The method does not increase the strength characteristics (limits of strength and fluidity) of the product. The main disadvantages of heat treatment of high-strength steels with quenching on martensite, with simultaneous shaping are stresses, injected during shaping, cooling, and structural transformations, which, at 3.98, lead to the formation of cracks and clumps of products. In a number of cases, treatment according to a known method is accompanied by the formation in the zone of maximum bend of germ micro cracks, which cause brittle fracture of products during subsequent operation. In addition, the disadvantage of this method is not high enough strength and ductility of products, which reduces their operational durability. The purpose of the invention is to increase the strength and reduce the cracking. This goal is achieved by the fact that in the known method of manufacturing products from structural steels, including heating the sheet preform to the austenization temperature, aging, shaping by bending, quenching and tempering. high-temperature thermomechanical treatment was preliminarily performed with tempering at 4OO-6QOC, the wire was bent at 600-650 ° C, and the quenching was conducted with air from the temperature above the beginning of the martensitic strip. A new technological process of manufacturing products includes high-temperature thermomechanical treatment (HTMT of the workpiece, which leads to a simultaneous increase in strength and resistance to crack propagation {fracture toughness), which greatly increases the operational durability of products. However, after this treatment, the hardness will remain relatively high, hgb makes machining difficult (for example, drilling holes, milling grooves). To eliminate this difficulty, it is necessary to carry out intermediate leave (for example, at 4OO-6OO ° C). Tempering at temperatures in the specified range reduces the hardness for machining, after which heating is carried out to the austenization temperature, with a short exposure at this temperature, which limits the development of austenite recrystallization, which eliminates the polygonized substructure and accordingly removes hardening from the preceding HTMO. In addition to this purely technological purpose of the softening tempering operation, it also plays an important role in stabilizing the substructure created at HTMO, increasing the effect of inheriting the increased complex of mechanical properties during regular quenching. Thus, this release is consistent with the ultimate goal of the invention, the achievement of high, strength and triadic resistance of parts. Cooling from austenizst temperature to temperatures. 20–3O G above the mara of the tenate point conducts at a rate exceeding the critical quenching rate, and then, after some holding, the product is released into the air. The use of such staggered cooling prevents the development of pearlite and intermediate transformations, while at martensitic it reduces quenching stresses that can lead to the formation of cracks. The choice of cooling mode is assigned from the C-diagram analysis for the given steel, taking into account the hereditary effect of the preliminary HTVO on the foundations of supercooled austenite. The choice of the forming temperature is due to the fact that both cutting (higher than ASZ) and low (slightly higher than M and) the forming temperature can lead to marriage (due to cracks). In the first case, shaping in combination with high temperature leads to recrystallization of austenite, i.e., the polygonized substructure created as a result of preliminary HTMT is eliminated, its beneficial effect on the properties of the finished product is removed. In the second case, shaping at a lower temperature, in addition to the need to use the power of the equipment, causes a sharp increase in the density of dislocations in martensite; this reduces the viscosity of the fracture. Shaping in the region of relative stability of supercooled austenite (6OO-650 C) retains the effect of strengthening and increasing the fracture toughness, since on the one hand these recrystallization temperatures, and on the other, austenite in this temperature range is quite plastic, and when it is loaded. (shaping) does not arise powerful clusters of dislocations. Example. Manufacturing of products (e.g., a shelf type) of steel grade 25XHM is carried out according to known and proposed methods. The known method of manufacture includes heating the sheet stock up to 940 + i 40 ° C, deformation with immediate quenching tempering at heating up to 870 ° + 10 ° C, cooling to,.

shaping by bending in the range of 600-650 ° С, subsequent cooling with air and tempering at 180 t 1О C.

985087

The table shows the properties of products that are wrinkled with lime and proposed by cnocj36aM.

Claims (3)

As can be seen from the table, an increase in strength and absence of cracks is possible only after processing by the proposed method. The use of the proposed method of manufacturing products from structural medium-carbon alloyed steels ensures complete elimination of tracein, which leads to 1OO% product yield, increase in strength, and significantly improves the quality of products, their durability and reliability. The invention The method of manufacturing products from structural steels, including heating of the billet to the austenization temperature, latching, shaping by bending, quenching and tempering, characterized in that, in order to increase strength and reduce cracking, high-temperature thermomechanical treatment with tempering at 40 ° -6OO ° C, bending is carried out at 6OO-65 ° C, and quenching is carried out with air cooling from temperatures of 2 ° -30 ° C above the beginning of the martensitic transformation. Sources of information taken into account in the examination. 1. USSR author's certificate number ZO8076, cl. C 21 D 1 / O2, 1969. 2. USSR Author's Certificate No. 5О1О87, cl. C 21 D 8 / GS, 1974. 3.BOLKHOVITINOV N.F. Metallography and thermal processing. M., Mechanical Engineering, 1965, p. 341-342.