CN1069526A

CN1069526A - Hot-boring cold-draw two-phase seamless steel tube

Info

Publication number: CN1069526A
Application number: CN 91105601
Authority: CN
Inventors: 魏风宝; 董鑫业; 李承基; 周健舒; 贾伯衡; 李顺中; 崔伍伦
Original assignee: TIANJIN CITY STEEL PIPE WORKS; Central Iron and Steel Research Institute; University of Science and Technology Beijing USTB
Current assignee: TIANJIN CITY STEEL PIPE WORKS; Central Iron and Steel Research Institute; University of Science and Technology Beijing USTB
Priority date: 1991-08-12
Filing date: 1991-08-12
Publication date: 1993-03-03

Abstract

A kind of two-phase seamless steel tube, it belongs to low-carbon (LC), low alloy steel and application thereof.Characteristics of the present invention be with C≤0.12%, Si=0.60～1.40%, Mn=1.25～1.70%, S.P≤0.035% be raw material through the tubulation base, hot piercing, cold-drawn are carried out finished products at last and are obtained a small amount of B microstructure of F+M+.The tensile strength of the pipe of producing with this method is greater than 392MPa, and unit elongation is greater than 26%.

Description

Hot-boring cold-draw two-phase seamless steel tube

The invention belongs to low alloy steel and application thereof.

Dual phase steel with ferrite (F)+martensite (M) or bainite (B) microstructure, as one of new steel grade of high-strength low-alloy steel, it is the new steel grade of developing in recent years with applied research, has cold-forming property preferably, also have solidity to corrosion preferably, therefore be widely used on various punching presses and non-punching press zero member.

At present, the production of colddrawing seamless pipe all needs repeatedly intermediate softening annealing to guarantee the recovery of cold-drawn performance, and the good cold deformation performance of dual phase steel is applied to produce colddrawing seamless pipe, can reduce the process annealing number of times, simplify production process, shorten Production Flow Chart, thereby reduce production costs, also can improve the quality of products simultaneously.

The present invention overcomes to produce weldless steel tube with soft steel and need to cause the shortcoming of complex process through intermediate softening anneal repeatedly, invent a kind of processing method that adopts low-carbon (LC), low-alloy dual phase steel production weldless steel tube.

The Chemical Composition of low-carbon (LC) of the present invention, low-alloy dual phase steel as shown in Table 1.

C	Si	Mn	S	P
					≤0.12	0.60～1.40	1.25～1.70	≤0.035	≤0.035

(wherein: Mn+Si=2.25～2.85)

Adopt the composition of this low-carbon (LC), low alloy steel, mainly consider the alloying principle of dual phase steel.In order to obtain duplex structure when reaching, should contain alloying elements such as a certain amount of silicon, manganese in the alloy at finished products in hot rolling, perforation back.Silicon is to promote proeutectoid ferrite to separate out effectively, but the cheap element little to the perlitic transformation kinetic effect.Manganese is to postpone the cheap element that perlite forms effectively.Enough manganese content is arranged, could guarantee that austenitic transformation forms martensite or bainite when cooling, and not change perlite into.

Manufacture method of the present invention is to be that raw material is realized through operations such as tubulation base, cold-drawn and finished product processing with above-mentioned low-carbon (LC), low alloy steel.Concrete technology is as follows.

1. tubulation base: with square billet through rolling or forge into circular pipe blank.

2. hot piercing: to 1200-1250 ℃, through 30-60 minute laggard eleven punch 11, after the perforation, air cooling quenched after second through 200-240 to room temperature or air cooling to 500 ℃, can obtain the microstructure of F+B with continuous furnace heating pipe.

3. cold-drawn: the operation according to hollow forging → cold-drawn (I) → cold-drawn → (II) process annealing → cold-drawn (III) → cold-drawn (IV) is carried out; " hollow forging ", " annealing " operation comprise operations such as corresponding pickling, cleaning, phosphatization, saponification, 740～900 ℃ of process annealing temperature, and be 10-20 minute total heat-up time in stove, air-cooled or air cooling, its microstructure is F+(12-16%) a small amount of B of M+.

4. finished products: annealing temperature 720-850 ℃, in stove, kept 10-20 minute.

As producing the seamless tube raw material, its composition is controlled to be as follows with 07 Mn Si steel:

C	Mn	Si	S	P
					0.07	1.65	0.66	0.015	0.010

Air cooling is to room temperature after the hot piercing, 800～900 ℃ of Cold Drawing Process process annealing temperature, and kept 15 minutes.800～850 ℃ of finished products kept 15 minutes in stove.Its microstructure is F+(12-14%) a small amount of B of island M+.

As producing the seamless tube raw material, its composition is controlled to be as follows with 08 Mn Si steel:

C	Si	Mn	S	P
					0.08	1.04	1.28	0.011	0.002

After the hot piercing, quench behind about 200～240 seconds to 500 ℃ of the air cooling, Cold Drawing Process process annealing temperature keeps air cooling after 12 minutes for 780-820 ℃.740-780 ℃ of finished products temperature.Its microstructure F+(13-15%) a small amount of M of B+.

As producing the seamless tube raw material, its composition is controlled to be as follows with 06 Mn Si steel:

C	Si	Mn	S	P
					0.06	1.39	1.40	0.009	0.003

Air cooling is to room temperature after the hot piercing.770～820 ℃ of Cold Drawing Process process annealing temperature also kept 12 fens, then air cooling.750～790 ℃ of finished products temperature; In stove, kept 17 minutes.The a small amount of M of its microstructure F+B+.

Two-way weldless steel tube specification limit of the present invention is 10～40 * 1.5～3.5 millimeters of ∮.Its product tensile strength is not less than 392MPa, and unit elongation is greater than 26%, and dimensional precision, mechanical property all meet or exceed the international common level of GB3087-82I() requirement.(is example with a kind of specification) as shown in Table 1

Project	GB 3087-82 requirement	Actual reaching
			External diameter	24.60～25.40	25.20-24.90
Wall thickness	2.25-2.87	2.40～2.57
			Tensile strength	390-590	500-525
Yield strength	245	320-360
			Extend	20	33-40

06 its annual corrosion speed VRY and 20 of Mn Si steel of the present invention ^#Steel is compared situation as shown in the figure.

Claims

1, a kind of two-phase steel pipe is characterized in that alloy ingredient C≤0.12% (weight), Si=0.60～1.40% (weight), Mn=1.25～1.70% (weight), S≤0.035% (weight), P≤0.0035% (weight) are realized through technologies such as tubulation base, hot piercing, cold-drawn and finished product processing for raw material, and is specific as follows:

1. tubulation base: with square billet through rolling or forge into circular pipe blank;

2. hot piercing: ℃ through 30-60 minute laggard eleven punch 11, perforation back air cooling quenches after second through 200-240 to room temperature or air cooling to 500 ℃ with continuous furnace heating pipe to 1200～1250

3. cold-drawn: according to the operation of hollow forging → cold-drawn I → cold-drawn II → process annealing → cold-drawn III → cold-drawn IV, 740～900 ℃ of process annealing temperature, at stove internal heating total time 10-20 minute, air-cooled or air cooling.

4. finished products: temperature keeps the 10-20 branches for 720～850 ℃ in stove, air-cooled.