SU1381191A1 - Steel - Google Patents

Abstract

The invention relates to the field of metallurgy, in particular, to the manufacture of an oil country tubing, for example tubing of strength group K according to GOST 632-80. The purpose of the invention is to increase the ductility of steel. The goal is achieved by additional doping of steel with calcium and limiting the titanium content. Steel has the following chemical composition, ias.%: Carbon 0.36-0.42; silicon is 0.2-0.4; manganese 1.0-1.27; titanium 0.03-0.045; aluminum 0.01-0.035; calcium 0.005-0.01; iron - the rest. The proposed composition provides for carrying out the smelting process without preliminary deoxidation, which is due to the weakness in the regulation of the pipe rolling process. In order to obtain a more uniform pipe structure, it is advisable to finish rolling by deformation of austenite in a non-two-phase region at a temperature not lower. 3 tab. i L

Description

GARDEN 00

This invention relates to metallurgy, in particular to the manufacture of pipes.

oil mix, for example, pump-compressor by strength group K according to GOST 632-80.

The purpose of the invention is to increase the ductility of steel.

The proposed steel is produced without prior oxidation. At the beginning, the crucified amount of aluminum is placed in the ladle, and then all deoxidizing agents and alloying elements together, thereby reducing crane operations.

A1 to p 0.010% (the upper limit of the content of acid-soluble aluminum is limited by the steel casting process, an increase in A1 cf 0.035% severely worsens the casting) during deoxidation, the formation of predominantly fine AljOj particles (they affect the inner surface of the pipes with less

In addition to aluminosilicates - ZMPO Al,; Oj 3510 ,, SFeO - AljOj 3SiO,) promotes the use of titanium as g of the curing element (titanium in this composition up to 0.025% acts as a modifier, and above - a micro-regulating element, the upper limit of Ti 7, 0.045 % limited by deterioration of ductility and toughness).

When the percentage content of titanium Ti is 0.045%, under other equal conditions, the strain hardening coefficient (D) sharply increases, and the ductility decreases. Under these conditions, cold cutting (the ground) of the metal becomes impossible.

Calcium in this steel is used as a modifier necessary for the refining of the hot rolled metal (for example, to reduce anisotropy, facilitate the process

metal cutting, etc.).

The lower level of the total grade composition of the proposed steel is limited by the possibility of achieving a yield point in hot rolled coals.

811912

6 to 50 kg / mm, and the top to obtain a high-quality surface when cutting tubular billet. The cutting process is greatly impaired if

% Mp

C 3, g 7 / 0,64% (C

ten

15

20

25

30 5 40

45 Carbon Silicon

eq C -. -----) or sG 15%, W 50%.

In order to obtain a more uniform pipe structure, it is advisable to finish the rolling by deforming austenite in a non-two-phase region at a temperature not lower (critical temperature at the onset of the phase transformation of the proposed steel).

Chemical compositions and indicators of the mechanical properties of the proposed steel are given in table. 1 and 2, data on the density - in the table. 3. S - 6,

D ---.

where D is the strain hardening coefficient;

 true stress strain;

e - true elongation;

 yield strength.

As follows from Table 3, the proposed steel, in comparison with the known one, has a higher ductility, which makes it possible to cold-cut it, excluding the hot cutting of the tubular billet.

Claims (1)

Invention Formula Steel containing carbon, silicon, manganese, titanium, aluminum and iron, characterized in that, in order to increase the ppasticity, it additionally contains calcium in the following ratio of components, wt.%: 0.36 - 0.42 0.20 - 0.40 1.0 - 1.27 0.03 - 0.45 0.010-0.035 0.005-0.01 Else Table 1 10.36 0,201,00,03 0,005 0,010 20.39 0.30 1.13 0.037 0.007 0.022 30, A2 0.401.27 0, OA5 0.010.035 Table 3 The effect of Ti percentage on indicators and. (f, tv steel