CN103614624B

CN103614624B - One kind low-alloy high-strength steel plate band of precipitated phase containing high density and rolling mill practice

Info

Publication number: CN103614624B
Application number: CN201310624648.1A
Authority: CN
Inventors: 高志国; 乔林锁; 王健; 王志温; 程德富; 乔团结; 张辉; 王海明; 康利明; 王小平; 郑永春
Original assignee: Baotou Iron and Steel Group Co Ltd
Current assignee: Baotou Iron and Steel Group Co Ltd
Priority date: 2013-11-27
Filing date: 2013-11-27
Publication date: 2018-09-04
Anticipated expiration: 2033-11-27
Also published as: CN103614624A

Abstract

One kind low-alloy high-strength steel plate band of precipitated phase containing high density and its rolling mill practice, chemical composition and content (weight percent) are：C0.05% 0.12%, Si≤0.50%, Mn1.20% 2.00%, P≤0.020%, S≤0.010%, Alt >=0.030%, Nb0.060% 0.080%, V0.051% 0.070%, Ti0.11% 0.15%, Mo0.24% 0.44%, Nb+V+Ti ＞ 0.23%, surplus are Fe and inevitable impurity.Hot rolling technology is：1,190 1260 DEG C of the heating temperature of steel ingot, soaking time 15 hours, 1,150 1200 DEG C of roughing temperature, 950 990 DEG C of final rolling temperature, 850 900 DEG C of finishing temperature, two sections of rolling overall reduction >=80%, slab wait for that temperature thickness is not less than 12mm.Average on-line cooling rate is more than 30 DEG C/s, and finished plate thickness is 4 10mm.Thus there is the steel plate of process excellent mechanical property, tensile strength to be more than 820MPa, and yield strength is more than 720MPa, and elongation percentage is more than 10%.Charp impact value (v-notch specimen size under normal temperature condition：5mmx10mm × 55mm) it is not less than 40J, it is not less than 20J under the conditions of 40 DEG C.

Description

One kind low-alloy high-strength steel plate band of precipitated phase containing high density and rolling mill practice

Technical field

The invention belongs to field of iron and steel, are related to one kind low-alloy high-strength steel plate band of precipitated phase containing high density and its roll Technique processed.

Background technology

Currently, low-alloy high-strength steel plate band is strengthened by tiny polygonal ferrite+a small amount of bainite mostly.Analysis It is less to go out phase amount, distribution is more local.For example, Zhou Qianxue et al. is with the larger precipitated phase (Nb, Ti) that size is 40~100nm (C, N) and size are that the tiny precipitated phase ε-Cu of 5~30nm are prepared for Ultra-low carbon high-strength weathering steel as main hardening constituent.So And the addition of copper certainly will cause copper on furnace wall to be enriched with, and increase and smelt prepurging process cost.In fact, by adding Entering the Nb of high-content, Ti elements and the low-alloy high-strength steel plate band illustration that C element formation compound is mutually strengthened are relatively fewer, this Patent discloses a kind of precipitated phase low-alloy high-strength steel plate band containing high density (Nb, Ti) C, mainly passes through strengthened nano precipitated phase Obtain high-strength high-plasticity strip of steel plate.It fully utilizes Nb, the advantages of Ti elements, obtains a kind of tensile strength and be up to 800MPa or more contains high density (Nb, Ti) C precipitated phase low-alloy high-strength steel plate bands and rolling mill practice.

Invention content

The object of the present invention is to provide a kind of low-alloy high-strength steel plate band of precipitated phase containing high density and its rolling mill practices.

It is described to realize that technical scheme is as follows, steel billet chemical composition is：C0.05%-0.12%, Si≤ 0.50%, Mn1.20%-2.00%, P≤0.020%, S≤0.010%, Alt >=0.030%, Nb0.060%-0.080%, V0.051%-0.070%, Ti0.11%-0.15%, Mo0.24%-0.44%, surplus be Fe and inevitable impurity, Middle Nb+V+Ti ＞ 0.23%.Steel billet containing chemical composition as above is put into heating furnace, 1190-1260 DEG C of heating temperature, heat preservation Time 1-5 hour.1150-1200 DEG C of roughing temperature, 950-990 DEG C of final rolling temperature, 850-900 DEG C of finishing temperature, two sections of rollings Overall reduction >=80%, steel billet wait for that temperature thickness is not less than 12mm.Averagely cooling rate is more than 30 DEG C/s online.Strip performance is excellent Different, tensile strength is more than 820MPa, and yield strength is more than 710MPa, and elongation percentage is more than 10%.Charpy impact under normal temperature condition It is worth (v-notch specimen size：5mm × 10mm × 55mm) it is not less than 40J, it is not less than 20J under the conditions of -40 DEG C.

Outstanding advantages of the present invention are that high density (Nb, Ti) C precipitated phases are rich in strip, main hardening constituent be it is a large amount of (Nb, Ti) C and a small amount of bainite are suitable for producing width 800-2000mm, thickness 3-10mm, and length is not more than the strip of steel plate of 12m.

Description of the drawings

Fig. 1 is microstructure photo under transmission electron microscope STEM patterns.

Specific implementation mode

The present invention is explained in detail with reference to embodiments.

Embodiment 1

The chemical composition and content (weight percent) of steel plate be：C0.079%, Si0.329%, Mn2.00%, P0.015%, S0.004%, Alt0.044%, Nb0.060%, V0.062%, Ti0.13%, Mo0.25%, surplus be Fe and Inevitable impurity.

Its rolling mill practice system is：1250 DEG C of billet heating temperature, soaking time 2.5 hours, 1200 DEG C of roughing temperature, essence 970 DEG C of temperature is rolled, 880 DEG C of finishing temperature, two sections of rolling overall reduction >=80%, slab waits for that temperature thickness is not less than 12mm, average 40 DEG C/s of on-line cooling rate.Sample detection, mechanical property danger measured value are shown in Table 1：

1 mechanics properties testing value of table

Microstructure photo is as shown in Figure 1.As seen from the figure, there are a large amount of high density (Nb, Ti) C precipitated phases in tissue.

Claims

1. a kind of low-alloy high-strength steel plate band of precipitated phase containing high density, it is characterised in that its chemical composition by weight percentage And content is：C0.05%-0.12%, Si≤0.50%, Mn1.20%-2.00%, P≤0.020%, S≤0.010%, Alt >=0.030%, Nb0.060%-0.080%, V0.051%-0.070%, Ti0.11%-0.15%, Mo0.24%-0.44%, Surplus is Fe and inevitable impurity；Nb+V+Ti ＞ 0.23%；The steel plate bandwidth 800-2000mm, thickness 3-10mm, Length is not more than 12m.

2. one kind low-alloy high-strength steel plate band of precipitated phase containing high density as described in claim 1, it is characterised in that its tension Intensity is more than 820MPa, and yield strength is more than 710MPa, and elongation percentage is more than 10%, v-notch half-size scale sample under normal temperature condition Charp impact value is not less than 40J, is not less than 20J under the conditions of -40 DEG C.

3. one kind low-alloy high-strength steel plate band of precipitated phase containing high density as described in claim 1, it is characterised in that precipitated phase For a large amount of (Nb, Ti) C precipitated phases.

4. a kind of rolling mill practice of the low-alloy high-strength steel plate of precipitated phase containing high density band of feature as described in claim 1, It is characterized in that 1190-1260 DEG C of the heating temperature of steel ingot, soaking time 1-5 hours, 1150-1200 DEG C of roughing temperature, finish rolling temperature 950-990 DEG C of degree, 850-900 DEG C of finishing temperature, two sections of rolling overall reduction >=80%, slab wait for that temperature thickness is not less than 12mm, Average on-line cooling rate is more than 30 DEG C/s.