JPS63282241A - Tool material for borine on high cr seamless steel pipe - Google Patents

Abstract

PURPOSE:To provide excellent seizing resistance and wear resistance to the titled tool material by molding the tool material by a cast alloy incorporated with specific ratios of C, Si, Mn, Cr, Mo, W and Nb into Fe and subjecting the surface thereof to an oxidized scale sticking treatment. CONSTITUTION:The tool material is molded from the cast alloy contg., by weight, 0.10-0.40% C, 0.10-1.00% Si, 0.20-2.00% Mn, <=0.95% Cr, 0.50-3.50% Mo, 0.50-3.50% W, 0.10-1.00% Nb and the balance consisting of Fe with inevitable impurities. Said tool material is then retained for about 1-24 hour in the temp. range of about 900-1,050 deg.C in an oxidizing atm. and is applied to the oxidized scale sticking treatment. In this way,the titled material having excellent wear resistance, by which no seizing is generated in the material to be rolled and having long service life is obtd.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to tool materials for seamless steel pipe manufacturing, and in particular,
The present invention relates to a material for a plug for a piercer or elongator that exhibits excellent seizure resistance and wear resistance when drilling steel.

<Prior art> A method for producing seamless steel pipes is to create a hollow material by drilling round or square steel pieces using the Mannesmann method or press method, and then elongate this hollow material using a mandrel mill, an elongator and a plug mill, etc. It is the best.

In each step of manufacturing this seamless steel pipe, the forming plug and guide shoe are exposed to severe abrasion conditions at high temperatures. Therefore, producing tools with excellent wear resistance at high temperatures and extending the tool life is one of the important issues in the production of seamless steel pipes using the above method. Its importance becomes even greater when high-alloy steel pipes are desired.

Conventional techniques regarding materials for perforation and elongator plugs include C:
0.1-0.25%, Cr: 1-3%, Ni: 1-9
%.

Any one of Mo and W or the total of the two is 0.3 to 3
% is an essential component, and an alloy material for a core metal having a Ni/Cr value of 1 to 3 has been proposed. Further, Japanese Patent Application Laid-Open No. 59-9154 filed by the present applicant contains a suitable amount of Mo, Nb or Mo in addition to the chemical composition C-3i Mn-Ni-Cr contained in a conventional drilling plug.

In addition to Nb, appropriate amounts of Mo, Nb, and even Al.

One or more of Zr, V, Co, and W are added, and in the case of drilling 13Cr stainless steel, the life is significantly extended.

However, recently S U, which has traditionally been difficult to manufacture using Mannesmann mandrel mills or plug mills,
1 such as 5304.316L, 321.347 austenitic stainless steel or austenitic-ferritic duplex stainless steel containing 22-25% Cr.
Steel materials containing 6% or more of Cr have come to be manufactured in large quantities. For this reason, even if alloy steel plugs such as those disclosed in the three inventions above are used, wear such as gouges and seizure of the rolled material to the plug will occur, resulting in an increase in the unit consumption due to the short life of the plug. Not only that, but it was also the cause of frequent internal defects in the pipe.

<Problems to be solved by the invention> The present invention has been made in view of the above, and is
6L, 321.347.22Cr and 25Cr
The purpose of the present invention is to provide a long-life plug that causes little wear and tear during drilling or elongation of duplex stainless steel and does not seize the rolled material.

Means for Solving the Problems> The present invention has the following weight ratio: C: 0.10 to 0.40%, Si: 0
．． 10~1.00%Mn: 0.2'O~2.00%
, Cr: 0.95% or less Mo: 0.50 to 3.5
0%, W: 0.50-3.50% Nb:
This is a tool material for drilling seamless high Cr steel pipes, which is formed from a cast alloy containing 0.10 to 1.00%, with the remainder consisting of Fe and unavoidable impurities, and the surface of which has been subjected to oxide scale adhesion treatment. In addition, in terms of weight ratio, C: 0.10 to 0.40%, Si: 0.1
0-1.00%Mn: 0.20'2.00%, C
r: 0.95% or less Mo: 0.50 to 3.50%
, W: 0.50 to 3.50%Nb: 0.1
Contains 0 to 1.00%, furthermore Ni: 0.50 to 3.50%, Co:
Contains one or more selected from 0.50 to 3.50% v 1.10 to 1.00%, and the remainder is formed from a cast alloy consisting of Fe and inevitable impurities, and its surface This is a tool material for drilling high Cr seamless steel pipes that has been subjected to oxide scale adhesion treatment.

Effect> The present inventors have repeatedly conducted experiments and studies in order to improve the life of a plug for drilling or elongating a material containing 16% or more of Cr. As disclosed in the above three inventions, all conventional drilling plugs contain Cr of 1% or more.
Attempts have been made to improve the service life by increasing the high-temperature strength due to Cr carbides and by forming oxide scales with excellent adhesion to the base iron due to the formation of Cr oxides.

The present inventors found that a conventional plug containing 1% or more of Cr
When drilling or elongating materials containing 6% or more Cr, oxide scale containing oxides of Cr may cause high Cr content during drilling.
It tends to adhere to the material to be drilled, and the oxidized scale on the plug side is scraped off by the material to be drilled, causing the insulation and lubrication effects to disappear, causing the plug to gouge or the material to be drilled to seize, significantly shortening its life. I discovered that.

Next, the experiments that formed the basis of the present invention will be explained.

Figure 1 shows (A) C: 0.50%, Si: 0.35%
.

Mn: 0.55%, Mo: 1.48%.

W 72.92%, Nb: 0.31%CB)
C: 0.29%, St: 0.33%.

Mn: 0.54%, 'Mo = 1.02%
.

W: 2.07%, Nb: 0.25%.

After being cast into a predetermined shape from a steel material with a base composition of Ni: 1.42%, Co: 1.01% and varying the Cr content, it is subjected to oxide scale adhesion treatment at 970°C for 4 hours in an oxidizing atmosphere. Using a plug made of: ・C: 0.015%, St: 0.35%, Mn: 1.5
3%.

Ni: 5.92%, Cr/22.6%,
Mo: 3.12%.

N: Outer diameter of duplex stainless steel containing 0.16% 20
A 7 m billet is drilled with an outer diameter of 192 m and a wall thickness of 13.
The lifespan when 51 hollows are manufactured continuously is C: o
, 31%, Si: 0.35%, Mn: 0.5
5%.

It was molded from a steel material containing Ni: 1.05% and Cr: 3.04%, and was heated for 950"CX 4 h in the above atmosphere.
It is expressed as a ratio to the life when the above-mentioned billet is continuously drilled into the above-mentioned hollow using a plug subjected to scale adhesion treatment, and is plotted against the Cr content of the plug.

It can be seen from FIG. 1 that when the Cr content exceeds 0.95%, the life of the plug decreases rapidly.

Based on this knowledge, the inventors found that 'C
By reducing the r content and applying a suitable high-temperature oxide scale adhesion treatment on the plug surface, the scale near the interface with the base iron is not scraped off by the drilled material containing 16% or more Cr during drilling, but rather the plug The composition consists mainly of FeO so that it is firmly welded to the surface, and also contains appropriate amounts of Mo, W,
Nb, Ni.

By adding Co and V to improve high-temperature strength and adhesion of surface oxide scale to the base steel, it is possible to obtain a long-life plug material for drilling and drawing of stainless steel containing 16% or more Cr. did it.

Next, the reason for limiting the chemical components in the present invention will be described. All component compositions herein are in percent by weight.

C: C is added to increase high-temperature strength, but if it is less than 0.10%, it has no effect, and if it exceeds 0.40%, cracks are likely to occur during use, significantly shortening the life of the plug.

Si: St is added for deoxidation, but if it is less than 0.10%, its effect will be small, and if it exceeds 1.00%, the amount of oxide scale attached will decrease and the life will be shortened.

Mn: 0.20% Mn is added to increase high temperature strength
If it is less than 2.00%, the effect is small, and if it exceeds 2.00%, thermal fatigue cracking is likely to occur due to the thermal history during drilling, reducing the service life.

Cr: Cr is added to form a scale on the surface that has good adhesion to the base metal alloy and has good heat insulation properties, and to increase high temperature strength by forming carbides of Cr, but it is added in an amount exceeding 0.95%. The scale composition near the interface between F e C
r z Oa , and when drilling a material containing 16% or more of Cr, the scale on the plug side is scraped off by the rolled material, resulting in a shortened life.

MO: Mo is added to increase high temperature strength, but 0.50
If it is less than 3.5%, the effect will be small, and if it exceeds 3.5%, the amount of oxide scale generated will decrease and the life will be significantly shortened.

W: W is added to increase high temperature strength, but 0.50%
If it is less than 3.5%, the effect will be small, and if it exceeds 3.5%, the amount of oxide scale produced will decrease and the life will be significantly shortened.

Nb: Nb is added to increase high temperature strength, but 0.05
If it is less than 1.0%, the effect is small, and if it exceeds 1.0%, cracks are likely to occur during drilling, reducing the lifespan.

Each of the above-mentioned limited amounts of C, Si, Mn, Cr, Mo, W, and Nb are essential components of the plug material for drilling or stretching of the present invention, and Ni, Co, and V are further added in the following limited amounts to 1 The object of the present invention can be achieved by having one or more species.

Ni: Ni promotes selective oxidation during heating in an oxidizing atmosphere and makes the scale at the interface look like roots, increasing adhesion and extending plug life, but if it is less than 0.50%,
The effect is small, and if it exceeds 3.0%, the amount of scale produced decreases and the life span is significantly deteriorated.

CO: Co increases high-temperature strength, promotes selective oxidation during heating in an oxidizing atmosphere, and generates many metal particles in the spools near the interface of the steel base, improving the adhesion between the scale and the steel base. Although it significantly increases the plug life and extends the life of the plug, it is 0.5
If it is less than 0%, the effect will be small, and if it exceeds 3.5%, the amount of scale generated will decrease and the life will deteriorate.

■: ■ is added to increase high temperature strength, but 0.05%
If it is less than i, o%, the effect will be small, and if it exceeds i,o%, plug cracking will easily occur during drilling, and the life will be significantly shortened.

In addition, the temperature during the scale deposition treatment in an oxidizing atmosphere was set in the range of 900 to 1050°C.When the temperature is below 900°C, the amount of scale generated is small, and when it exceeds 1050°C, there are many voids in the scale. In either case, the life of the plug is significantly shortened due to decreased adhesion.

If the holding time in the above temperature range is less than 1 hour, the amount of scale generated will be small and the life of the plug will be shortened.
The production amount reaches saturation within 3 hours, and it is meaningless to hold it any longer because it will only reduce productivity and increase the heating unit consumption.

<Example> The inventive materials and comparative materials whose chemical compositions are shown in Table 1 were heat-treated in an oxidizing atmosphere to remove oxide scale under the conditions shown in Table 2, and the chemical compositions were determined using these plugs. C: 0.015%, Si: 0.35%, Mn
: 1.53%, Ni: 5.92%, Cr:
22.6%, Mo: 3.12%, N: 0.1
Table 1, Table 2 shows the lifespan of comparative materials when a billet of duplex stainless steel with an outer diameter of 207mm containing 6% is continuously manufactured into a hollow with an outer diameter of 192mm and a wall thickness of 13.5mm+. is 1, and those of the present invention material are expressed as multiples thereof, and the second
Shown in the table.

As is clear from the plug life ratios in Table 2, all the materials of the present invention have excellent lifespans.

<Effects of the Invention> As is clear from the above examples, the present invention limits the chemical composition of the tool material for seamless steel pipe production, and at the same time, it
By applying an oxide scale adhesion treatment that is maintained for 4 hours, we produce a tool material with excellent wear resistance and a long life that prevents the rolled material from burning when drilling or stretching stainless steel containing 16% or more Cr. It made it possible to do so.

As a result, it is possible to improve the wear and tear of the plugs for drilling or drawing, which is the biggest problem when manufacturing high-alloy seamless steel pipes containing 16% or more of Cr using Mannesmann mills. In view of the increasing demand for high-alloy steel pipes in the field of seamless steel pipes, their industrial value is significant.

[Brief explanation of drawings]

Figure 1 shows CSt Mn Mo-W-Nb or CSt
-3i-Mn-Mo-W-Nb-C-3i- over the life of a drilling plug containing 3i- within the limited range of the present invention
It is a figure showing the influence of content.

Claims (2)

[Claims] (1) Weight ratio: C: 0.10-0.40%, Si: 0.10-1.00
%Mn: 0.20-2.00%, Cr: 0.95% or less Mo: 0.50-3.50%, W: 0.50-3.50
%Nb: 0.10 to 1.00%, with the remainder being Fe and unavoidable impurities. A tool material for drilling seamless high Cr steel pipes, which is formed from a cast alloy and has its surface treated with oxide scale adhesion. . (2) Weight ratio: C: 0.10-0.40%, Si: 0.10-1.00
%Mn: 0.20-2.00%, Cr: 0.95% or less Mo: 0.50-3.50%, W: 0.50-3.50
%Nb: 0.10-1.00%, further Ni: 0.50-3.50%, Co: 0.50-3.5
0% V: Contains one or more selected from 0.10 to 1.00%, and the rest is formed from a cast alloy consisting of Fe and inevitable impurities, and its surface is treated with oxide scale adhesion. High Cr seamless steel pipe drilling tool material.