JPS60128242A - High manganese steel for nonmagnetic drill collar - Google Patents

Abstract

PURPOSE:To obtain a high Mn steel for a nonmagnetic drill collar with high strength, superior ductility and toughness by adding specified percentages of C, Si, Mn, S and V to Fe. CONSTITUTION:A high Mn steel consisting of, by weight, 0.01-0.50% C, <=3.0% Si, 18-35% Mn, <=0.20% S, 0.60-3.0% V and the balance Fe with inevitable impurities is prepd. To the steel may be added one or more among 0.5-7.0% Cr, 0.1-7.0% Ni, and 0.1-3.0% Cu and/or one or more among 0.01-1.50% each of Nb, Ti and Al and 0.05-3.0% each of Mo, W and Co. The high Mn steel has superior resistance to stress corrosion cracking and superior machinability besides said properties.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to steel for use in non-magnetic drill collars often used in oil extraction.

(Prior technology) During oil drilling, do you have to repeatedly go down the wire line and lower the detector to measure the inclination and orientation of the well? However, the drill collar, which is the lowering position of the tester, is required to be non-magnetic because the tester is fully equipped with a magnetic con/RS. In addition, in recent years, as oil fields have moved from land to the sea, the number of inclined drilling drills has increased.In these inclined drilling drills, a probe 5' is incorporated inside the non-magnetic drill collar to continuously transmit detailed information from the underground to the surface. The method of sending is being taken. In addition to being non-magnetic, the Mata Drill Collar has the ability to withstand various large external stresses during drilling, has high strength, excellent fc ductility and toughness, and is resistant to stress corrosion cracking in the drilling environment. required. Other drill colors are
Screw I71. ! It is also necessary to have good fx machinability since it is used for machining such as boring and boring.

JP-A-58-45 on steel for non-magnetic drill collars
There is one proposed in Publication No. 363. This invention contains C, NO, 01 to 0.5%, Si2 or less, Mn1
O-30%, Ni0.01-5%, Cr6.5
-15%, Mo0.01-3%, 80.2% or less,
Finished at a low temperature of 611-650 to 950℃ with the remainder made of iron and high! +5ti K (we are trying to add f.

However, it is generally difficult to impart uniform strength to a long piece of material when making a large cut during warm processing such as this, and the anisotropy of the material increases.

(Objective of the invention) The present invention solves these problems and achieves a relative magnetic permeability of 1.0.
Stable non-magnetic property of 20% or less, uniform material, yield strength of 60 kvA or more, tensile strength of 75% or more, and elongation of 20% or more! It has a ductility of 740% or more and a toughness with a Charpy impact absorption energy of 3.0 m or more at room temperature, and is also excellent against muddy water, which is a corrosive environment during excavation, and the Ct and H2S contained therein. A steel having high stress corrosion cracking resistance is provided mainly by appropriately blending components C and V.

(Structure and operation of the invention) The composition of the present invention is C0.01-0050 in weight%.

The basic components are Si3.0% or less, Mn1B-35%, SO, 20% or less.
-7.0%, one or more of Cu0.1-3.0%, and Nb and Ti.

One or more of At, Mo, W, and Co are substituted with Nb.

0.01 to 1.50% for Ti and At respectively9
0.05-3.0% for M02W and Co, respectively.
It is a steel containing all the ingredients in an appropriate combination.

The reason for limiting the component composition of the present invention as described above will be explained in detail below.

C is effective as an austenitizing element and is an essential component for forming vanadium carbide, which is effective for strengthening, and for this purpose it must be contained in an amount of 0.01% or more. However, excessive inclusion of C must be avoided. Figure 1 shows that various types of high Mn austenitic steels including C and V are melted and hot rolled into plates with a thickness of 20yan, which are then solution-treated at 1150°C and then heated to 60mm.
Effect of addition of C and ■ on the strength, ductility, and toughness of high Mn-based austenitic steel aged for 1 to 100 hours at 0 to 650°C Total 0.2% Result of investigation on the relationship between yield strength, reduction of area, and Charpy impact energy shows. In other words, to ensure the target strength, ductility, and toughness, the C content i must be 0.50% or less, and to obtain even better ductility and toughness, the V′i
It is desirable that the C content be 0.30 or less.

S! 1 is an effective component for increasing strength. Addition of a large amount of silica makes the austenite chord unstable and impairs non-magnetic properties, so the content was limited to 3.0% or less.

M n i't austenite is an extremely effective component for stabilizing non-magnetic properties, improving ductility, and improving stress corrosion cracking resistance in sulfide and chloride environments. Since the full effect is exhibited at 18% or more, the lower limit was set at 18%. However, if the amount exceeds 35%, the strength increases too much, leading to a decrease in ductility and toughness, so it is set to 35 or less.

S is inertly effective in improving the stiffness of high Mn austenitic steel, and is contained in an amount of 67 tons. However, since adding a large amount particularly reduces toughness, the content was set at 0.20%.

As already mentioned, (2) is an extremely effective element for increasing strength. 0 to obtain the target strength. It is necessary to add more than C0. However, since addition of more than 3.0% causes high toxicity and a total decrease in toughness, the upper limit was set at 3.0%.

Addition of Cr, Ni and CO is effective in stabilizing austenite-2 and improving non-magnetism and toughness, and the addition of these components alone or in combination increases the total strength. In order to obtain this effect, Cr must be 0°5 or more, N
Both i and Cu must be contained in an amount of 0.1% or more.

However, if the addition of Cr exceeds 7.0%, it causes deterioration of ductility and toughness, so it must be 7.0% or less. Although it is better to add a large amount of Ni, adding a large amount of Ni to the surface will increase the cost, so it is set to 7.0% or less. Also, Cu
Containing a large amount of Moamashi increases hot cracking and surface flaws1
Rice content was reduced to 3.0% or less.

Nb, Ti, At, Mo, W are effective components for increasing the strength of the steel.
AtVi 0.01% or more each, Mo, W, Co1
Must contain 0.05% or more. However, too much Nb content impairs ductility and toughness.
, Ti, and At are each 1.50% or less,'
For Mo, W, and Co, the content must be 3.0% or less.

In addition, 0.0% is used to improve hot workability and increase stiffness.
001 to 0.020% of Cai may be contained.

The steel of the present invention is produced, for example, according to the steps described below. In other words, a melting furnace such as a converter or an electric furnace is used, and if necessary, a vacuum degassing method, a ladle refining method,
A molten steel with a specified composition is obtained by remelting all phases, such as remelting, and after making it into a steel ingot, it is heated at 1100 to 1250℃.
It is made into steel billets by heating to a temperature and blooming and rolling, or by continuous casting. After the steel billet is reheated to 1100 to 1250 DEG C. by the same method, or immediately after the steel billet is produced, it is rolled or forged at 500 DEG C. or higher to form a predetermined shape. Furthermore, in order to obtain stable high strength, it is desirable to perform an aging treatment for 10 to 600 minutes at a temperature of 500° C. to 80° F. after rolling by water cooling or air cooling.

It is more effective if solution heat treatment is performed at 900-1200°C before this aging treatment. In addition, during the prescription process, 9
Processing may be performed once or more at a temperature of 00° C. or less and a processing rate of 30% or less. Furthermore, in the aging treatment temperature range, especially 67
Real winding below 0°C gives the steel better ductility than real winding above that temperature.

(Example) Next, an example of the steel of the present invention will be described. Table 1 shows the chemical composition and heat treatment conditions of the comparative steel made from the steel of the present invention. Table 2 shows the mechanical properties of drill collars cast under the conditions in Table 1,
Shows stress corrosion cracking resistance due to sulfides and chlorides. The manufacturing process for these drill collars consists of steel ingots melted in an electric furnace.
The outer diameter is 90~2 by heating to 100℃ and rolling or forging.
Make a round bar of 80 gourds, heat treat it and then add as needed)
Finished by cutting and cutting, such as cutting and boring.

The drill collars of Steel Ugly 1 to 10 have the composition range of the present invention and satisfy the target mechanical properties t' such as strength, ductility and toughness, and the results of the sulfide stress corrosion cracking test in the NACEO environment It can be seen that the Kl sec dimension is 62 kg/1 tnn" or more, which is very excellent, and the chloride stress corrosion cracking resistance is also excellent. In addition, these inventive steels were subjected to 20% cold working strain. '(The relative permeability in the case is 1.o o
It was stable non-magnetic with i~1.010.

Steel N [111 to 13 are comparative steels. N11ll and 12
The C content of this steel deviates from the present invention, or because of this, the elongation and drawing do not reach the target values.

Since the N[Li2 steel has a low Mn content and deviates from the present invention, the austenite phase is unstable, and therefore the sulfide stress corrosion cracking resistance is poor.

(Effect of the invention) It has the effect of being excellent in force corrosion cracking resistance.

[Brief explanation of the drawings] Figure 1 shows the progress made in the strength, toughness, and ductility of manganese steel.
and ■Graph showing the influence of ingredients. Agent: Patent attorney Masamitsu Akizawa and 2 others

Claims (1)

[Claims] (1) C0.01 to 0.50% by weight. 8i3.0chi or less, Mn18-35%. High manganese steel for non-magnetic drill collars containing 80.20% or less, V 0.60-3.0%, and the balance consisting of iron and inevitable impurities - (2) wt%, co, o i ~ 0.50%. Si 3.0% or less, Mn 113-35%. 80.20% or less, V 0.60-3.0%, and Cr 0.5-7.0%. Ni 0.1-7.0%. Cu0.1' 3.0% Ngan steel. (3) In the weight department, c o, o i ~ 0.50 chi. Si 3.0% or less, Mn 18-35%. 80.20 or less, V 0.60 to 3.0%, and further contains one or more of Nb, Ti, At, Mo, W, and Co, and 0 for Nb, Ti, and At, respectively. High manganese #l for non-magnetic drill collars, containing .01-1.50% and 0.05-3.0% for Mo, W, and Co, respectively, and the remainder consisting of iron and inevitable impurities.
l. (4) In weight percent, co, o i ~ 0.50%. Si 3.0% or less, Mn 18-35%. 80.20% or less, V 0.6 0-3.0%, and Cr 0.5-7.0%. N i 0.1-7.0%. All units include one or more of Cu0.1-3.0%, and Nb, T
One or more of i, At, Mo, W, and Co, and 0.01 to 0.01 or more for Nb, Ti, and At, respectively.
1.50%, 0.0 each for Mo, W, Co
A high manganese steel for non-magnetic drill collars, which contains 5-3.0 g and the balance is iron and unavoidable impurities.