RU1795916C - Method for rolling cylindrical ingots - Google Patents

Abstract

Usage: rolling cylindrical ingots of titanium on crimping mills. The purpose of the invention is to increase the yield of metal by reducing the end trim when rolling blooms from cylindrical ingots of titanium and titanium alloys on crimping reversing mills. SUMMARY OF THE INVENTION: A cylindrical titanium ingot is successively crimped with rolls with a pitching roll. Rolling is carried out with a ratio of the length 1D of the deformation zone to the average roll height hcp equal to 0.45-0.80 in each pass, and at least one pass during compression in thickness is carried out with a ratio of 1 d / hcp of 0.71-0, 80. 1 C.p. f-crystals, 1 ill., 3 tab. ate with

Description

FIELD OF THE INVENTION The invention relates to rolling production and can be used in the rolling of ingots in billet mills.

Known methods of rolling blooms from cylindrical ingots, including sequential compression of the metal rolls with a pitching roll. Rolling is carried out under conditions of uneven deformation along the strip height, which is indicated by the factor of the shape of the deformation zone — the ratio of the length of the deformation zone 1D. to average hcp roll height. At 1D / hCp .0.20-0.42 or 0.25-0.43, the non-uniformity of deformation (the lower the d / hcp, the greater the non-uniformity) inevitably leads to the development of deep tension at the ends of the roll, which determines the increase in the trim. which reduces the yield.

There is also a known method of rolling blooms from cylindrical ingots, comprising sequential compression of the metal rolls with a pitching roll.

The disadvantage of this method is also the low yield. When rolling with U / hcp 0.27-0.61 due to uneven deformation along the strip height, the drawing mainly produces surface layers of metal, especially in the first passes, which leads to the development of iron at the ends of the roll. In the last passes, the unevenness of the deformation decreases (1D / hcp increases to 0.61), however, in this case, too, the strand develops with each pass, which determines the weight of the cut-off, which is 65-70 kg / t good.

sl

h

(I Yu

 Gj

The purpose of the invention is to increase the yield during rolling of titanium alloys by reducing the end trim.

The goal is achieved in that the rolling is carried out at 1d / HCP 0.45-0.80 in each pass. In addition, at least one pass during compression in thickness is performed with 1 d / hep 0.71-0.80.

Dependence of weights D | from d / MSr when rolling cylindrical ingots is of a complex non-monotonic nature (see drawing, curves 1-3 - rolling of cylindrical ingots with a diameter of 730-750 mm from titanium alloys of the type VT-1-0, OT 4-0, VT 20, respectively, on the crimp camp 1250).

For all titanium alloys, when passing through Gd / hcp 0.43-0.44, the intensity of the function is D | f (1D / hcp) changes dramatically. Indeed, at 1d / G1avr 0.43, the contraction to a greater degree depends on the shape factor of the deformation zone than at 1D / hep 0.44. For example, when d / hcp changes from 0.4 to 0.3 (by 0.1), the iron increases by 25-35 mm. At d / hcp 0.44, the intensity of the function D1 - f (1D / hcp) drops sharply, for example, when d / psr changes by the same amount (0.1), the weight increases (decreases) by 5-10 mm:

The inflection in the function graph is explained by the fact that the absolute compression and the length of the deformation zone have a constant value along the width of the deformation zone.

At 1d / НСр 0.69-0.70, no contraction is formed, i.e. a transition to almost uniform deformation along the height of the deformation zone is observed. At d / hcp 0.70, the iron has a negative value, i.e. at the ends of the roll, a bulge appears in the central part, since the central layers receive a larger stretch than the surface.

Thus, a rolling is inevitably formed during rolling with A / hCp 0.69, and the rolling mode in this case should correspond to the task of minimizing the rolling,:.

. For Ifl / hcp 0.45 and more, not only the absolute value of the iron in each pass is less than that for 1d / g1Sr 0.43, but the total (accumulated) iron is close to minimum due to a sharp decrease in the intensity of the function Д | f (1d / hcp).

When a cylindrical ingot is compressed in two mutually perpendicular directions, the total tensile is greater in the plane along which the total compression is greater, i.e. by the thickness of the roll. Therefore, to minimize end trim

due to the alignment of the values of the iron during compression in thickness and width of the strip, it is necessary to carry out rolling with compression in thickness at (d / hcp 0.70. In this case, the accumulated iron is compensated by a larger stretch of the central layers than surface ones. Naturally, more than 1 d / g | cf, the greater the compensation of the iron, however, on crimping mills 1d / bCp 0.8 is the limit,

Thus, an increase in the yield by reducing the end trim is achieved if the rolling of cylindrical ingots from titanium alloys BOB is carried out at d / psr 0.45-0.80. In addition, in order to compensate for the greater trimming along the thickness, at least one passage with compression in thickness is carried out at d / hcp 0.71-0.80, i.e. above critical

the magnitude of the transition to uniform deformation ..

The method is carried out as follows.

At the mill 1250 cylindrical ingots

with a diameter of 730-750 mm and a mass of 6.0 tons are rolled according to various compression modes into blooms with a cross section of 305x450 mm. The trim value corresponding to the complete removal of the iron is weighed, and the value of the iron

measure up.

Tables 1 and 2 show the results obtained for ingots with a diameter of 750 and 730 mm, respectively. The weight of the trim is 15-20 kg / t suitable.

From table 1 it follows that within the crimp regime I / hcp 0.45-0.74, and in the third pass when compressing in thickness U / hcp 0.74, In the fifth and seventh passes, smoothing passes

to remove broadening, preventing overflow of gauge. In the ninth pass - thickness control.

From the table. 2 it follows that within the compression mode d / hcp 0.46-0.80, and in the second pass when compressing through the thickness Ifl / hcp 0.80. In the fourth and sixth passes, smoothing passes are made.

 The existing compression mode is shown in table. 3 (diameter 750 mm).

Under the existing regime, only in two out of eight passes d / hcp 0.44.3 d 0.70 is not achieved in any pass. In the sixth, eighth, tenth and twelfth pass, ironing is carried out to remove broadening and control the thickness of the roll.

Claims (2)

SUMMARY OF THE INVENTION 1. A method for rolling cylindrical ingots, comprising sequentially compressing metal with rolls with a pitch of a roll, characterized in that, in order to increase the yield when rolling titanium alloys by reducing the end edge, rolling in each pass is carried out with a ratio of the length of the deformation zone to the average roll height d / hep 0,45- -0,80 in each pass, 2. The rolling method according to claim 1, with the exception that both at least one pass during compression in thickness is carried out with a ratio d / psr of 0.71-0.80,  Tilting in the 90s  90 ° tilting. Table t table 2  Tilting in the 90s Table 3