CN102560243A

CN102560243A - Rolling method for Q345 steel plate with thickness of 50-100mm

Info

Publication number: CN102560243A
Application number: CN2011103933172A
Authority: CN
Inventors: 余泽金
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: 2011-12-02
Filing date: 2011-12-02
Publication date: 2012-07-11

Abstract

The invention relates to a rolling process for a Q345 steel plate with thickness of 50-100mm, which belongs to the technical field of moulding. The Q345 steel plate with thickness of 50-100mm is rolled on a heavy and medium plate rolling mill with double racks by an ingot blank with thickness of 200-230mm and the hot rolling state of the steel plate meets the GB1591-2008 standard requirements. The rolling process is as follows: (1) heating the ingot blank to 1200-1240 DEG C and keeping temperature for 1.5-2.5 hours; (2) after temperature keeping, conducting hot rolling and controlling the initial rolling temperature at 1100-1180 DEG C; (3) controlling the initial rolling temperature in a second stage at 880-950 DEG C, enabling the accumulative rolling reduction in the second stage to be greater then or equal to 25% and controlling the final rolling temperature at 850-930 DEG C; and (4) conducting cooling at the cooling speed of 10-30 DEG C/S in a first stage after rolling, wherein the temperature after cooling is 650-680 DEG C. The steel plate has the mechanical properties as follows: 320-340 MPa of yield strength, 490-525 MPa of tensile strength, 25.5-34% of elongation, 110-160 J of impacting energy (normal temperature) AKV (transverse) and cold bending (transverse) 180-degree d=3a.

Description

A kind of thickness is the rolling method of 50～100mm Q345 steel plate

Technical field

The invention belongs to field shaping technique, relating to thickness is the hot-rolling method of the Q345 steel plate of 50～100mm.

Background technology

The Q345 steel is good because of its comprehensive mechanical property; Low-temperature performance also can; Plasticity and weldableness are good; Be used as live load bearing structures such as mesolow force container, oil tank, vehicle, lifting machine, mining machinery, power station, bridge, component of machine, building structure, common metal structural part etc. in a large number, be applicable to that hot rolling, controlled rolling, normalizing, normalizing add the engineering steel of tempering and as-quenched condition supply and general structure is not less than 3mm with thickness steel plate, steel band.At present, domestic production thickness generally all need carry out normalizing greater than the Q345 steel plate of 40mm or normalizing adds thermal treatment process such as tempering or quenching, can satisfy standard and user's requirement to guarantee steel plate.

The Q345 steel plate that the present invention relates to thickness 50～100mm adopts plate mill production, need not heat-treat technology and can satisfy the GB1591-2008 standard to its performance requriements, can supply customer demand.So the Q345 steel that the present invention relates to greatly reduces the production cost of steel, has shortened the production cycle.

Summary of the invention

The objective of the invention is to adopt the hot rolling production technique to produce the Q345 steel plate that thickness is 50～100mm.

Technical solution: through to the adjustment of Q345 steel chemical composition and controlled rolling and technology for controlled cooling, adopting the thick strand of 200～230mm to produce thickness is the Q345 steel plate of 50～100mm.

Technical scheme of the present invention is achieved in that

Q345 steel provided by the invention, its chemical ingredients by mass percent is: C:0.15～0.18%, Si:0.3～0.5%; Mn:1.30～1.50%; P :≤0.03, S :≤0.05, Al:0.015～0.030%; Nb:0.02～0.04%, all the other for matrix Fe with can't detect for impurity element.

The present invention's employing has above-mentioned chemical ingredients and thickness is the strand of 200～230mm; Rolling thickness is the Q345 steel plate of 50～100mm on the plate mill of two-shipper frame; The full GB1591-2008 standard-required of hot-rolled steel plate attitude, concrete Rolling Production is carried out according to the following steps:

(1) steel billet is heated to 1200～1240 ℃, is incubated 1.5～2.5 hours;

(2) carry out hot rolling after the insulation, the control start rolling temperature is 1100～1180 ℃;

(3) the two-stage start rolling temperature is controlled at 880～950 ℃, two-stage accumulative total draught >=25%, and finishing temperature is controlled at 850～930 ℃;

(4) roll the back fs with the cooling of 10～30 ℃/S speed of cooling, cooled temperature is 650～680 ℃.Subordinate phase arrives room temperature with the steel plate air cooling.

Description of drawings

Fig. 1 is that the thick Q345B steel plate of 60mm is horizontal 1/4th, the metallographic structure at thickness 1/4th places;

Fig. 2 is that the thick Q345B steel plate of 80mm is horizontal 1/4th, the metallographic structure at thickness 1/4th places;

Fig. 3 is that the thick Q345B steel plate of 100mm is horizontal 1/4th, the metallographic structure at thickness 1/4th places.

Embodiment

Below in conjunction with embodiment the present invention is further described.

Embodiment 1

Selecting thickness is the strand of 200～230mm; On the plate mill of two-shipper frame, being rolled into thickness is the Q345 steel plate of 50～100mm; The hot-rolled steel plate attitude satisfies the GB1591-2008 standard-required, and is listed in its chemical ingredients and weight percent content such as the table 1, is rolled according to following rolling technology:

(1) steel billet is heated to 1220 ℃, is incubated 2 hours;

(2) carry out hot rolling after the insulation, start rolling temperature is 1150 ℃;

(3) the two-stage start rolling temperature is 950 ℃, two-stage accumulative total draught 30%, 890 ℃ of finishing temperatures;

(4) be cooled to 680 ℃ with 20 ℃/S speed of cooling after the rolling completion and carry out heat and rectify, air cooling is to room temperature then.

Table 1 Q345B steel chemical composition control (mass percent %)

The mechanical property of the billet size that adopts, rolled sheet material thickness, steel plate is seen table 2.

Table 2 Q345B steel plate mechanical property

Fig. 1～3 are seen in the metallographic structure of steel plate.

Claims

1. the rolling technology of the thickness Q345 steel plate that is 50～100mm, its chemical ingredients by mass percent is: C:0.15～0.18%, Si:0.3～0.5%; Mn:1.30～1.50%, P :≤0.03, S :≤0.05; Al:0.015～0.030%, Nb:0.02～0.04%, all the other are matrix Fe and the micro impurity element that can't detect; It is characterized in that the strand that 200～230mm of above-mentioned chemical ingredients and content is thick, being rolled into thickness is the Q345 steel plate of 50～100mm.

2. the rolling technology of the Q345 steel plate that a kind of thickness as claimed in claim 1 is 50～100mm is characterized in that

(1) steel billet is heated to 1200～1240 ℃, is incubated 1.5～2.5 hours;

(4) roll the back fs with the cooling of 10～30 ℃/S speed of cooling, cooled temperature is 650～680 ℃; Subordinate phase arrives room temperature with the steel plate air cooling.

3. the rolling technology of the Q345 steel plate that a kind of thickness as claimed in claim 1 is 50～100mm; It is characterized in that having following mechanical property: ys 320～340Mpa; Tensile strength 490～525Mpa; Unit elongation 25.5～34%, ballistic work (normal temperature) AKV (horizontal stroke) 110～160J, 180 ° of d=3a of clod wash (horizontal stroke).