CN1478614A

CN1478614A - Rolling method of seamless steel pipe

Info

Publication number: CN1478614A
Application number: CNA021472378A
Authority: CN
Inventors: 西川公介
Original assignee: Sanyo Special Steel Co Ltd
Current assignee: Sanyo Special Steel Co Ltd
Priority date: 2002-08-29
Filing date: 2002-10-18
Publication date: 2004-03-03
Also published as: JP2004082196A

Abstract

Provided is a method of rolling a seamless bearing steel tube which has no outside surface defects and which prevents the generation of fine wrinkles equivalent to surface wrinkle defects on the outer surface of the bearing steel tube. In the method of rolling the seamless bearing steel tube, the S content of bearing steel is adjusted to <= 0.015mass%, temperature before rolling with an Assel mill to 1,030 to 1,130[deg.]C, the draft to the outside diameter in stretch rolling with the Assel mill to 2.5 to 35.0% and the draft of thickness to 5.0 to 56.5%.

Description

The milling method of seamless steel pipe

Technical field

The invention relates to and make the manufacture method that outer surface does not have the seamless steel pipe of flaw.

Background technology

On the manufacturing process of seamless steel pipe, carry out the technology of tubing by the shaped steel steel billet and generally carry out according to following.That is to say, will in heating furnace, heat, on the punch shaped steel steel billet under the high temperature is being rolled perforation, be rolled stretching by A Ersai three-roller type pipe mill again as the shaped steel steel billet of seamless steel pipe raw material.Then, on reheating furnace, heat once more, on the fine finishining sizing mill, finish fixed size, on the rotation sizing mill, carry out the adjustment of external diameter again.In this technical process, in the rolling, drawing operation of being undertaken, on the steel pipe outside, can produce the tiny wrinkle that is equivalent to surperficial fold fault by A Ersai three-roller type pipe mill.Particularly the generation in high its this fault of bearing steel of S content is more remarkable.

As the countermeasure that solves above-mentioned fault, alleviate it when the stainless steel that discloses on the flat 7-308703 communique the stainless steel of martensite or 2 phases is rolled be created in the method that inner surface peels off fault on A Ersai three-roller type pipe mill as opening the spy.In this method,, be the external diameter compression ratio that is controlled on the mandrel contact position being that stainless steel hollow pipe below 0.25 carries out under the situation of rolling, drawing on the tube rolling in rotation with wall thickness/external diameter.

And, open the spy and to disclose the rolling method of Cr-Mo perforating steel pipe on the clear 64-75107 communique.In this method, when making the Cr-Mo steel pipe by drilling/rolling, the content of S in the steel is controlled at below 0.008%, and the corresponding heating-up temperature of determining punch when perforation steel billet, and the beginning temperature of punch perforation is located at more than 1050 ℃ with the content of S in the steel.

But, it is to prevent from that stainless steel inner surface in martensitic stainless steel or 2 phases from producing to peel off fault that above-mentioned spy opens disclosed content on the flat 7-308703 communique, rather than be object, and do not consider the countermeasure that prevents for the fault of outer surface to be subjected to the S content very big bearing steel that influences.And, it is object that the spy opens the Cr-Mo steel pipe that clear 64-75107 communique discloses with drilling/rolling on the punch, prevent that it from producing countermeasures such as peeling, interlayer, but be not the countermeasure that prevents of the trickle wrinkle that is equivalent to surface blemish that on the outer surface of bearing steel, produces.

Summary of the invention

Present inventors, here, can by the content of S in the restriction bearing steel constitution and on A Ersai three-roller type pipe mill restriction external diameter and wall thickness compression ratio, effectively prevent to be equivalent to the generation of the fine cracks of bearing steel outer face surface flaw.That is to say and to make the seamless steel pipe that outer surface does not have flaw.

Therefore, the objective of the invention is to make the seamless steel pipe that outer surface does not have flaw, can obtain fabulous industrial effects such as best in quality, that yield rate is high, and flaw is little thus.

The method of making seamless steel pipe of the present invention is:

Be ready to the bearing steel of S content below 0.015 quality %, this bearing steel is heated to after 1030～1130 ℃, be 2.5～35.0% in this bearing steel external diameter compression ratio, the wall thickness compression ratio is under 5.0～56.5% the condition, is rolled the operation of stretching by A Ersai three-roller type pipe mill.

And the best operating position of the present invention is, above-mentioned external diameter compression ratio is 7.0～25.0%, the wall thickness compression ratio is 12.5～48.0%.

Description of drawings

Figure 1A be whole skeleton diagram, the Figure 1A about A Ersai three-roller type pipe mill be oblique view,

Figure 1B is a profile.

Fig. 2 is the graph of a relation of expression external diameter compression ratio and wall thickness compression ratio.

The specific embodiment

Describe the present invention in detail according to appended drawings below.

Fig. 1 is the whole skeleton diagram about three-roller type pipe mill of the present invention, and Figure 1A is an oblique view, and Figure 1B is a profile.Shown in this Figure 1A and Figure 1B, the hollow pipe 2 that has inserted plug 1 rotates and transfers by 3 rollers 3 that lug boss is installed.And, will insert under plug 1 state hollow pipe 2 by these rollers 3 by continuously in the shape of a spiral shape ground its external diameter and wall thickness are compressed, and the wall thickness of the hollow pipe 2 between roller 3 and the plug 1 is reduced.

But, with above-mentioned bearing steel with rolling processing hot-working character difference the time, can produce the blind crack that is equivalent to fold on the outer surface.Present inventors, occurrence cause with regard to wrinkle on the surface outside, when A Ersai three-roller type pipe mill carries out drawing/rolling, made clear reason that wrinkle produces and the S amount in the steel grade composition, heating-up temperature and external diameter compression ratio and wall thickness compression ratio between relation.Particularly C, Cr and the high steel pipe of Mo content in bearing steel because compare with other steel alloy because be easy to generate overheatedly, are to be rolled under the high temperature more than 1200 ℃ as the general game that prevents chill mark.In the present invention, consider that the S content in the steel of wrinkle and the relation of furnace temp take place on the surface, the temperature with A Ersai three-roller type pipe mill before rolling is controlled at below 1030～1130 ℃, the S amount of bearing steel is controlled at below 0.015%.

The reason below 0.015% that S content is controlled at quality is to consider like this.Bearing steel and carbon steel tubing etc. are compared and are easy to generate the flaw point, when particularly being rolled by A Ersai three-roller type pipe mill, the temperature of its A Ersai three-roller type pipe mill before rolling surpasses 0.015% o'clock of quality at 1030～1130 ℃, S content will produce the chill mark fault.Therefore, S content is defined as below 0.015% of quality.That is to say that the bearing steel steel billet for preventing that the content that fault reduces S from being effectively, obtain this effect and with regard to being necessary the content of S is controlled at below 0.015% when carrying out drawing/rolling with A Ersai three-roller type tube rolling.Though considered that as the one of the main reasons that fault takes place hot-working character is poor, this is the former thereby rapid reduction of FeS because the content increase of S makes hot-working character.

The temperature of A Ersai three-roller type pipe mill before rolling is controlled at 1030～1130 ℃ reason to be had and followingly can see.The temperature of A Ersai three-roller type pipe mill before rolling produces the outer surface fault greatly because of the thermal deformation resistance during less than 1030 ℃, therefore, and be with 1030 ℃ as lower limit.And the temperature before rolling is if surpass 1130 ℃ because in the bearing steel content of C many can produce in crystalline phase circle overheated.Therefore, its scope is decided to be 1030～1130 ℃.Also can be 1050～1110 ℃.

In the method for the invention since the drawing/rolling of A Ersai three-roller type pipe mill be 2.5～35.0% in the external diameter compression ratio, the wall thickness compression ratio is to carry out under 5.0～56.5% the condition.Its reason is appreciated that with reference to Fig. 2.Fig. 2 is the graph of a relation between external diameter compression ratio and the wall thickness compression ratio.As shown in Figure 2, the external diameter compression ratio surpasses at 35.0% o'clock and can sharply produce the outside fault, therefore, will on be defined as 35.0%.And though less than not producing the outside fault at 2.5% o'clock, it is bad and can not be rolled to produce engagement between three rollers.Also have, if the wall thickness compression ratio surpass 56.5% can because the processing heating produce overheated, therefore, will on be defined as 56.5%.And less than though the outside fault did not take place in 5.0% o'clock, it is bad and make rolling can not carrying out to produce engagement between three rollers.Therefore, the external diameter compression ratio is controlled at 2.5～35.0%, the wall thickness compression ratio is controlled at 5.0～56.5% scope.

Embodiment

Below, specify the present invention according to embodiment.

Be ready to bearing steel SUJ (JIS G4805 (1990)), diameter is the steel billet of φ 140mm.This SUF4 steel is the steel that C:0.95～1.10%, Si:0.15～0.35%, Cr:1.30～1.60%, Mo:0.10～0.25% and remainder Fe and any composition (Mn, P, S) are formed by content.Use this steel billet, the external diameter after will boring a hole is rolled on A Ersai three-roller type pipe mill as the pipe of φ 140mm.When this as-rolled condition, the relation of external diameter compression ratio and wall thickness compression ratio and the outside fault state that produces under this kind situation are represented with table 1.As shown in table 1, No1～10th, example of the present invention, No11～18th, comparative example.From this table 1, can see comparative example No11 and produce the outside fault because of external diameter compression ratio height.It is overheated that comparative example No12 produces because the wall thickness compression ratio is high.Comparative example No13～15 produce because external diameter and wall thickness compression ratio are all low that engagement between three rollers is bad to make rolling can not carrying out.Although comparative example No16～18 are because many being rolled also under suitable processing conditions of the content of S can produce wrinkle.The corresponding fault that in example of the present invention, does not all produce the outside in No1～10.

Table 1

?No	Composition is formed (mass%)				Temperature before three-roll pipe mill is rolling (℃)	External diameter compression ratio (%)	Wall thickness compression ratio (%)	Outside fault situation	Whether take place overheated	Remarks
	Composition is formed (mass%)										????S	????Si	????Cr	????Mo
	????1	??1.01	??0.012	??1.40							????S	????Si	????Cr	????Mo	??0.11	??1032	????2.9	????5.3	????○	????○	Example of the present invention
????2	????1	??1.01	??0.012	??1.40	??0.99	??0.011	??1.39	??0.11	??1055	????5.2	????50.0	????○	????○		??0.11	??1032	????2.9	????5.3	????○	????○
????2	????3	??1.01	??0.013	??1.40	??0.99	??0.011	??1.39	??0.11	??1055	????5.2	????50.0	????○	????○	??0.18	??1050	????7.8	????11.0	????○	????○
????4	????3	??1.01	??0.013	??1.40	??0.99	??0.011	??1.43	??0.13	??1080	????10.2	????44.7	????○	????○	??0.18	??1050	????7.8	????11.0	????○	????○
????4	????5	??0.98	??0.012	??1.40	??0.99	??0.011	??1.43	??0.13	??1080	????10.2	????44.7	????○	????○	??0.13	??1100	????13.6	????54.7	????○	????○
????6	????5	??0.98	??0.012	??1.40	??0.98	??0.010	??1.39	??0.19	??1115	????18.2	????9.3	????○	????○	??0.13	??1100	????13.6	????54.7	????○	????○
????6	????7	??0.99	??0.012	??1.39	??0.98	??0.010	??1.39	??0.19	??1115	????18.2	????9.3	????○	????○	??0.17	??1052	????20.3	????24.7	????○	????○
????8	????7	??0.99	??0.012	??1.39	??0.98	??0.014	??1.40	??0.13	??1048	????25.0	????8.0	????○	????○	??0.17	??1052	????20.3	????24.7	????○	????○
????8	????9	??1.00	??0.011	??1.41	??0.98	??0.014	??1.40	??0.13	??1048	????25.0	????8.0	????○	????○	??0.12	??1040	????30.1	????49.3	????○	????○
????10	????9	??1.00	??0.011	??1.41	??1.01	??0.008	??1.38	??0.13	??1100	????34.4	????20.7	????○	????○	??0.12	??1040	????30.1	????49.3	????○	????○
????10	????11	??0.99	??0.010	??1.37	??1.01	??0.008	??1.38	??0.13	??1100	????34.4	????20.7	????○	????○	??0.12	??1096	????2.0	????35.6	Can not be rolling	????-	Comparative example
????12	????11	??0.99	??0.010	??1.37	??1.10	??0.013	??1.40	??0.14	??1082	????42.2	????38.0	????×	????○	??0.12	??1096	????2.0	????35.6	Can not be rolling	????-
????12	????13	??0.98	??0.009	??1.38	??1.10	??0.013	??1.40	??0.14	??1082	????42.2	????38.0	????×	????○	??0.13	??1062	????36.4	????58.0	????×	????×
????14	????13	??0.98	??0.009	??1.38	??1.01	??0.012	??1.38	??0.12	??1073	????20.0	????62.7	????○	????×	??0.13	??1062	????36.4	????58.0	????×	????×
????14	????15	??1.00	??0.010	??1.40	??1.01	??0.012	??1.38	??0.12	??1073	????20.0	????62.7	????○	????×	??0.10	??1053	????28.6	????4.2	Can not be rolling	????-
????16	????15	??1.00	??0.010	??1.40	??1.01	??0.020	??1.37	??0.10	??1068	????14.3	????26.7	????×	????○	??0.10	??1053	????28.6	????4.2	Can not be rolling	????-
????16	????17	??0.99	??0.025	??1.40	??1.01	??0.020	??1.37	??0.10	??1068	????14.3	????26.7	????×	????○	??0.14	??1102	????20.7	????40.0	????×	????○
????18	????17	??0.99	??0.025	??1.40	??0.99	??0.018	??1.41	??0.13	??1095	????25.7	????38.7	????×	????○	??0.14	??1102	????20.7	????40.0	????×	????○

As mentioned above, limit the content of S in the bearing steel constitution in the present invention, and be limited in the compression ratio of its external diameter and wall thickness when being rolled on the three-roller type pipe mill, thus, can be reduced in the fine cracks that is equivalent to chill mark that takes place on the outer surface of bearing steel significantly, the industrial production such as generation that improve quality of item, raising job efficiency, minimizing fault are effectively had excellent effect.

Claims

1, a kind of milling method of seamless steel pipe is characterized in that, comprising:

Prepare the bearing steel of S content below 0.015 quality %,

After this bearing steel is heated to 1030～1130 ℃,

To this bearing steel make that it is 2.5～35.0% in the external diameter compression ratio, the wall thickness compression ratio is under 5.0～56.5% the condition, the operation that is rolled by the three-roller type pipe mill.

2, the milling method of seamless steel pipe as claimed in claim 1 is characterized in that described external diameter compression ratio is 7.0～25.0%, and described wall thickness compression ratio is 12.5～48.0%.