SU1752466A1 - Method of making sized rods, mainly of structural carbon and alloyed steels for producing articles by cold upsetting - Google Patents

Abstract

SUMMARY OF THE INVENTION: The method includes hot rolling a billet, heat treatment, turning to a depth of (0.03 .., 0.04) d and cold drawing with a degree of deformation equal to 0.0036-0.0038 -d-100%. where d is the diameter of the cool bar. 3 tab.

Description

The invention relates to metallurgy and can be used to produce high-quality long products from structural carbon and alloyed steels, intended for the manufacture of products by cold heading.

A known method for the production of long products for cold heading, including the smelting of metal in a furnace, pouring it into molds weighing 8.35-15.5 tons, heating ingots to the optimum plasticity temperature, rolling them first on a squeeze, then in the cages of the blank mill to obtain cutting a workpiece with a section of 60x60 + 150x150 mm, cleaning surface defects, reheating and rolling the workpieces on a continuous mill mill with minimum tension until the varietal profiles of the required sections are obtained,

The disadvantage of this method of producing long products is the increased contamination of the metal with non-metallic inclusion, its gas saturation. In addition, laminated rods are characterized by low surface quality, ovality profile. During cold reverse extrusion of cup-type products, macrostructure defects are not completely stamped and in some cases can lead to unacceptable leakage of the bottom of the products.

The closest in technical terms to the proposed method is the production of calibrated long products, including hot rolling, heat treatment, cold drawing.

The disadvantage of this method in the production of intermediate billets of calibrated long products for cold-heading products is that the round profile of intermediate size is cold drawn unprepared for this operation due to significant internal stresses in the metal resulting from uneven cooling after hot rolling. In addition, due to the lack of scientifically based regimes, you often produce hot-rolled rod drawing;} if unfavorable | SL Yu

stress profile with the prevailing action of tensile stresses leading to a decrease in the metal and, consequently, to the formation of surface defects. This leads to the fact that even the smallest surface defects under the influence of residual tensile stresses gain their development during cold landing, contributing to increased rejection of finished products.

The aim of the invention is to increase the yield by increasing the plastic properties of the metal prior to cold slugging.

The goal is achieved in that according to the method of producing a calibrated rod, mainly from structural carbon and alloyed steels, intended to produce products by cold heading, including hot rolling, heat treatment, turning and cold drawing of the workpiece, according to the proposal, turning the rod is carried out before drawing to a depth of 0.03–0.04 in the diameter of a cold-drawn bar, and cold-drawing of the turned bar is carried out with a degree of deformation equal to (0, QQ36-0.0038) d100%, where d is the diameter of coldness chick bar.

For any bar size in the range of their changes from 6.5 to 34 mm, the optimal (critical) degree of deformation during drawing was determined, which ensures the maximum ductility of the metal before a cold landing.

The method is carried out as follows.

In the melting unit, steel is produced with low sulfur content, phosphorus and residual elements (nickel, chromium, copper), with minimal contamination of nonmetallic inclusions and homogeneous chemical composition, for which steel is deoxidized in the ladle by silicocalcium and aluminum. The melted liquid steel is subjected to out-of-furnace treatment with inert gases and poured into molds weighing 8.35-15.5 tons siphon from below.

The ingots were rolled on a blooming mill with a 90 ° roll-over through the first two passes, followed by blooming blooms in the process stream using a fire stripping machine and rolling on a continuous-billet mill to obtain blanks of the required sections, for example, 60x60-150x150 mm. You can use the above sections, spilled on UN PC. To remove surface defects formed during rolling on the billet mill or after

casting on UN PC, blanks are subjected to continuous stripping on machine tools, for example, on the Heinrich Pay machine, heated to the optimum plasticity temperature, usually 1050-1180 ° C, and rolled on a section or wire mill to obtain a round profile of intermediate size, defined from the ratio

Dnp d + (0.03-0.04) cL Ah, where d is the diameter of the cold-drawn bar, required by request, before disembarking, mm, the range of variation in the sizes of rods produced in the USSR for cold heading is 6.5-34 mm ;

(G,) d - depth of turning of the rolled-rolled mountain, mm;

Ah- absolute compression when drawing mm.

The resulting mountain chiseled round profile of intermediate size is turned. The depth of turning is selected from specific conditions. With a significant depth of surface defects, the thickness of the layer to be removed during turning is selected on the basis of 0, Q4ci, with an insignificant damage to the bar by surface defects, the thickness of the layer to be removed during turning is 0.03d.

The final stage of making a cold-drawn bar is that drawing has a number of features based on the results of an experimental study.

Grade-calibrated steel of different sections is characterized by axial and radial texture. The ductility of the metal increases with increasing intensity of the orientation of the crystallites along the rolling axis, especially the orientations 220, 222 and 420, while the density of the indicated orientations in the radial directions is lower. Crystallographic orientations of the grains have an additional protective effect on the properties of the steel. The component composition of the axial and radial textures of finished rolled products, in addition to the chemical composition of the steel, is influenced by the degree of deformation during cold drawing.

Analysis of the experimental data presented in Table. 1 shows that, at certain degrees of deformation, when drawing, there is an increased density of the above orientations along the axis of the calibrated rolled material and a reduced density of these texture components in the radial direction.

Cold drawing with a degree of deformation that is different from the optimum leads to a change in the component composition of the texture: the relative intensity of reflection in the axial decreases and, on the contrary, there is an increase in texture density in the radial direction, which leads to a decrease in ductility of the metal during a cold landing, and as a result, increased rejection of finished products.

With an increase in the diameter of the upsetting rod, the optimum degree of deformation during drawing increases in direct proportion from 2.4% for a 6.5 mm diameter to 12.6% for a 34 mm diameter rod.

Numerous experiments to determine the effect of the degree of deformation during drawing on the quality indicators of finished products have established that the smallest amount of defects in the manufacture of products by increasing the plastic properties of the metal before disembarking is achieved with a degree of deformation during drawing determined from the ratio (0 , 0036-0.0038) d-100%, where d is the diameter of the cold-coated rod.

In tab. Table 2 presents the results of experimental studies on the effect of the relative reduction during drawing on the mechanical and plastic properties of the metal before a cold landing. For all the tested cold-drawn rods, there preceded the turning of Hot-rolled rods by the value of 0.04 times the diameter of the cold-drawn rod.

The obtained research results indicate that when drawing rods of various sections with an optimal degree of deformation, the plasticity of the metal increases by 6.5-9.0%, which has a positive effect on the rejection of finished products.

Tests of 15FФA steel samples of various sections at different degrees of deformation on the draft by 0.5; 0.66 and 0.75 of the original height of the sample (50-70 samples per point) proved the effectiveness of the application of the turning operation not after drawing, as in the prototype, but before drawing and drawing with optimal degrees of deformation (Table 3).

A known method is taken as the base object for calculating the expected effect.

Claims (1)

Invention Formula A method of producing a calibrated rod, mainly structural carbon and alloyed steels, intended for cold-heading products, including hot rolling, heat treatment, turning and cold drawing of the workpiece, characterized in that in order to increase the yield by increasing the plastic properties, turning blanks are carried out to a depth of (0.03-0.04) d, and cold drawing is carried out with a degree of deformation equal to (0.0036-0.0038) d-100%, where d is the diameter of a cold drawn rod, mm. Upper Bounding (0, OAd) Value of Turning VALUE Table 1 Table Upper boundary 10,04 (value of the turning) x x rt h & x 6.5 23 23 34 6.5 6.5 23 23 and h |, 0,00355 0,0085 0,0039 0.00361 0,0065 0,0037 0.00375 0,0038 oh ozz 0,0035 0,0039 0,0041 0.0036 0.0037 0.0038 0.0031 0.0034 0.0039 0.0043 0,0036 0.0037 0.0038 0,0034 0,0035 G.004G 0.0036 0.0037 0.0033 0,0032 0,0055 0,0039 Oh, OOI 0.0036 0.0037 0.0038 0, 0.0039 0.0043 0.0036 0.0037 0.0038 3 50 34 37 40 44 47 5 0 9 5 4 5 7 , 6 , 6 3, 5 , 1, 6, 9 2 g 6 35 40 45 4 0 9 5 four 5 7 5, 4, 6 , 1, 5, 9 671 663 675 6.9 623 618 624 647 645 649 65 603 605 600 643 644 635 639 590 593 53 / 670 670 674 618 621 619 649 651 657 64С 601 605 602 644 633 638 591 592 586 5DS 605 607 562 560 56 And h 561 597 595 598 605 551,554,553 587 592 591 594 542 538 540 599 HOSA 604 563 561 564 597 603 604 599 551,554,552 592,587,531 541 539 541 57.4 56.5 56.9 62.0 62.3 61.9 62.2 61.8 59.3 58.5 58.9 59.0 64.1 64.6 64.3 59.8 59.9 60.4 60.9 65.0 65.2 65.5 57.3 5v, 7 56.3 63.0 62.0 62.2 59.2 53.3 59.6 -56,6 64.1 64.5 64.3 588 60.3 60,8 65.1 65.3 65.6 182,184,178 150 159 160 157,152 177 184 181 179 160 162,159 191 183 188 185 166 169 158 181 188 179 1S1 158 157 182 183 184 176 160 162 160 189 185 187 165 168 159