CN102899564A

CN102899564A - Extra-deep drawing Ti+Nb-IF steel cold rolling and annealing process

Info

Publication number: CN102899564A
Application number: CN2012104639833A
Authority: CN
Inventors: 冯岩青; 张晓燕; 王勇; 张秀飞; 白雅琼
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd; Inner Mongolia Baotou Steel Union Co Ltd
Priority date: 2012-11-16
Filing date: 2012-11-16
Publication date: 2013-01-30

Abstract

The invention relates to an extra-deep drawing Ti+Nb-IF steel cold rolling and annealing process. A plate blank comprises the following chemical components according to weight percentages: less than or equal to 0.005% of C, less than or equal to 0.2% of Mn, less than or equal to 0.01% of P, less than or equal to 0.008% of S, greater than or equal to 0.015% of Alt, 0.02-0.06% of Ti, 0.018-0.041% of Nb, less than or equal to 0.006% of N and the balance of Fe and trace of impurities which cannot be detected. A cold rolling process adopts five-pass cold rolling, with the total rolling reduction of the five-pass cold rolling being 75%-82%; and an annealing treatment process comprises the following steps: two-stage heating, with the heating rate of 70-85 DEG C per hour and 30-45 DEG C per hour respectively, the annealing temperature of 700-735 DEG C, and the heat preservation time of 8-15 hours, then adopting three-stage cooling, with the cooling rate of 25-35 DEG C per hour, 35-45 DEG C per hour and 15-25 DEG C per hour respectively, and cooling to room temperature. The extra-deep drawing Ti+Nb-IF steel cold rolling and annealing process has the advantages that IF steel samples treated by the process has excellent deep drawability, with the longitudinal tensile strength of 280-325MPa, the yield strength of 120-175MPa, the elongation of 40-55%, n of 0.20-0.28, and r of 2.0-3.0; and with the transverse tensile strength of 290-330MPa, the yield strength of 120-180MPa, the elongation of 40-50%, n of 0.20-0.28, and r of 1.9-2.9.

Description

Cold rolling and the annealing process of a kind of super deep-draw Ti+Nb-IF steel

Technical field

The invention belongs to metallurgical technology field, relate to the cold rolling and annealing process of a kind of super deep-draw Ti+Nb-IF steel.

Background technology

The characteristics of Ultra-low carbon gapless atomic steel (IF steel) are that the carbon nitrogen content is very low, and add Ti and Nb in steel, form C, the N compound of Ti and Nb, carbon, nitrogen interstitial atom in the steel are eliminated, thereby had superior deep drawability.Form in the IF steel cold-rolled process { the 111} plane texture starts process through dislocation, makes that { storage power of 111} increases.Because dislocation storage speed is relevant with grain orientation, make it have higher deformation energy storage, in the annealing process, these subgrains (or crystal grain) are annexed thereafter the crystal grain of other orientation with preference return and forming core in position, make that { the 111} plane texture is further strengthened.The molten amount of grain-size, precipitate form and C, N interstitial atom and substitutional atom Ti, Nb, P, Si etc. also is to affect { the principal element that 111} texture forms in the annealing process in addition.

In order to improve IF steel deep drawability, formulate suitable cold rolling and annealing process is very necessary.Application number is that 201110450985.4 Chinese invention patent discloses a kind of advanced automobile with the IF steel and the annealing process that contain niobium and titanium, and the described annealing process of this patent is not suitable for large industrial mass manufacture, is only applicable to small sample and anneals to obtain excellent properties.

Summary of the invention

The purpose of this invention is to provide a kind ofly produce flexibly, construction investment is few, be fit to small-scale production in batches have a cold rolling and annealing process of super deep drawability Ti+Nb-IF steel.

Technical scheme of the present invention is as follows:

Steel of the present invention, the chemical composition of its slab and weight percent content should meet: C≤0.005%, Mn≤0.2%, P≤0.01%, S≤0.008%, Alt 〉=0.015%, Ti 0.02-0.06%, Nb 0.018-0.041%, N≤0.006%, all the other are Fe and the trace impurity that can't detect; Its cold-rolling process adopts five passages cold rolling, and the cold rolling total reduction of five passages is 75%-82%; Annealing treating process is: two stages heated up, heating rate is respectively 70-85 ℃/hour and 30-45 ℃/hour, annealing temperature is 700 ℃-735 ℃, soaking time is to adopt the cooling of three stages after 8-15 hour, rate of cooling is respectively 25-35 ℃/hour, 35-45 ℃/hour, 15-25 ℃/hour, is cooled to room temperature.

Advantage of the present invention is: the IF steel sample after the art breading has excellent deep drawability thus, and endwise tensile strength reaches 280-325MPa, yield strength 120-175MPa, and unit elongation 40-55%, n 0.20～0.28, and r 2.0～3.0; Transverse tensile strength reaches 290-330MPa, yield strength 120-180MPa, and unit elongation 40-50%, n 0.20～0.28, and r 1.9～2.9.

Description of drawings

Fig. 1 is 700 ℃ of annealing process curve figure;

Fig. 2 is annealing sample metallographic structure figure;

Fig. 3 observes precipitate FeTiP+Ti (Al) N and precipitate energy spectrogram for the SEM of annealing sample;

Fig. 4 is tem observation precipitate TiN, TiC and TiS and the precipitate energy spectrogram of annealing sample;

Fig. 5 is 700 ℃ of annealing sample Texture α orientation line orientation density profiles.

Embodiment

The invention will be further described below in conjunction with embodiment:

Embodiment 1

Put into process furnace with intending rolling slab, the chemical composition of slab and weight percentage are: C 0.0035%, and Mn 0.15%, P0.008%, and S 0.004%, and Ti 0.042%, and Nb 0.021%, N0.004%, all the other are Fe and the trace impurity that can't detect.

The cold rolling total reduction of five passages is 80%, and draught per pass is respectively 34.6%, 36.3%, 32.2%, 26.6%, 4.8%, sees Table 1.Annealing treating process is: two stages heated up, be 7.0 hours heat-up time fs, heating rate is 80 ℃/hour, be warming up to 580 ℃, subordinate phase heat-up time is 3.5 hours, and heating rate is 35 ℃/hour, be warming up to 700 ℃, soaking time is 11 hours, then adopts three stages coolings, rate of cooling to be respectively 30 ℃/hour, 40 ℃/hour, 20 ℃/hour.According to the mechanical property detected value of the IF steel sample after the above-mentioned art breading see Table 2, table 3, table 4, heating curve such as Fig. 1, texture curve such as Fig. 4, in the sample so that { 111} texture is as main.

Table 1 cold roling reduction

The vertical mechanical property of table 2 and n, r value

R _P0.2/MPa	Rm/MPa	R _P0.2/Rm	A%	n	r
						125	295	0.42	44	0.26	2.1
145	300	0.48	43	0.268	2.3
						135	305	0.44	44	0.27	2.2

Table 3 transverse mechanical performance and n, r value performance

R _P0.2/MPa	Rm/MPa	R _P0.2/Rm	A%	n	r
						149	315	0.47	43	0.26	2.2
138	325	0.42	42.5	0.25	2.3
						142	315	0.45	44	0.24	2.0

[0023]45 ° of direction mechanical properties of table 4 and n, r value performance

R _P0.2/MPa	Rm/MPa	R _P0.2/Rm	A%	n	r
						151	315	0.48	42	0.25	2.4
137	305	0.45	44	0.25	2.0
						145	315	0.46	44	0.25	2.4

[0025]?

Claims

1. the cold rolling and annealing process of a super deep-draw Ti+Nb-IF steel, it is characterized in that: chemical composition and the weight percent content of plate slab meet: C≤0.005%, Mn≤0.2%, P≤0.01%, S≤0.008%, Alt 〉=0.015%, Ti 0.02-0.06%, Nb 0.018-0.041%, N≤0.006%, all the other are Fe and the trace impurity that can't detect; Its cold-rolling process adopts five passages cold rolling, and the cold rolling total reduction of five passages is 75%-82%; Annealing treating process is: two stages heated up, and heating rate is respectively 70-85 ℃/hour and 30-45 ℃/hour, and annealing temperature is 700 ℃-735 ℃, and soaking time is 8-15 hour.

2. the cold rolling and annealing process of super deep-draw Ti+Nb-IF steel according to claim 1 is characterized in that: adopt the cooling of three stages after the annealing, rate of cooling is respectively 25-35 ℃/hour, 35-45 ℃/hour, 15-25 ℃/hour and is cooled to room temperature.