CN103173598A - Annealing-free medium-high carbon steel plate making technology - Google Patents

Abstract

The invention relates to an annealing-free medium-high carbon steel plate making technology, and belongs to the technical field of steel rolling technologies. A technical scheme adopted in the invention is characterized in that the technology comprises the operations of heating furnace heating, vertical roll rolling, roughing scale removal, roughing rolling, intermediate cooling, precision rolling scale removal, precision rolling, laminar cooling, reeler reeling and concentrated pile cooling, the intermediate cooling operation is carried out after the roughing rolling operation and before the precision rolling scale removal operation and is realized through cooling plate blanks by a cooling device, and the cooling capability of the cooling device makes the temperature of the plate blanks decrease to below 840DEG C. The technology has the following beneficial effects: the elongation rate after fracture of produced products obviously rises, the hardness of the products decreases by 7.2-21%, the proportion of ferrite in the structure of the products is above 60%, ferrite crystal grains are appropriately coarsened, the pearlite colony is small and dispersed, and the cementite sheet in pearlite is attenuated, fragmented and partially granulated. An annealing operation after rolling can be avoided because of the low hardness and high plasticity in order to reach an online softening purpose.

Description

A kind of annealing type medium high carbon steel plate manufacturing process of exempting from

Technical field

The present invention relates to a kind of annealing type medium high carbon steel plate manufacturing process of exempting from, belong to the steel rolling process technical field.

Background technology

Mainly for the manufacture of cutlery and hardware tools, in the product deep-processing process, material hardness generally appears too high due to the medium high carbon steel plate, deep processing distortion difficulty, the problem such as the processing units wearing and tearing are large.It is generally acknowledged that Spheroidizing Annealing is to reduce the best process means of medium and high carbon steel hardness, but incident is that production cost increases, the production cycle multiplication, and the problem such as difficult quality guarantee in heat treatment process, a kind of production technique that can exempt annealing operation and can make medium high carbon steel plate lower hardness is badly in need of in this area.

Summary of the invention

The object of the invention is to provide a kind of annealing type medium high carbon steel plate manufacturing process of exempting from, in its hot rolling production process, the medium high carbon steel plate is directly obtained softening, thereby save the annealing operation after hot rolling, avoid annealing operation to cause the surface decarburization of steel plate, be conducive to the stable article quality, but and save energy, reduce costs, environmental contamination reduction solves the problems referred to above that background technology exists.

Technical scheme of the present invention is: a kind of annealing type medium high carbon steel plate manufacturing process of exempting from, comprise that process furnace heating, roughing de-scaling, roughing are rolling, intercooling,--the finish rolling de-scaling, finish rolling is rolling, laminar flow is cooling, reeling machine batches and concentrate the cooling in heap operation, described intercooling operation, after slab carries out the roughing rolling process, advance--before finish rolling de-scaling operation, by refrigerating unit, slab is carried out coolingly, the cooling power of refrigerating unit is cooled to below 840 ℃ slab.

Described roughing rolling process: roughing mill possesses the high-power ability of depressing, and draft reaches more than 65%, thereby effectively reduces the rolling load of finishing mill, alleviates the pressure of finishing train; Described finish rolling rolling process: the finish rolling stage adopts the rolling even ferrite area of two-phase region rolling, rely on deformation induced Transformation Principle, increase on the one hand ferritic ratio in tissue, the refinement ferrite crystal grain, carbon concentration in supercooled austenite is improved, and dislocation and substructure density increase; Finishing mill possesses the ability of high speed tandem rolling, and the logical steel second flow of finish rolling end frame is not less than 20m ²/ s reduces temperature drop, completes rolling.

Each procedure technology parameter is as follows:

(1) process furnace heating process: heating of plate blank is followed heating-soaking-insulation system, and 1000～1150 ℃ of Heating temperatures are incubated 1 hour, guarantees that heating of plate blank is even, and without obvious blackspot, on elongated direction, base cross direction, the temperature difference is no more than 30 ℃;

(2) edge rolling, roughing de-scaling, roughing are rolling: drop into side guide and edge rolling, rolling load 50～100t before roughing; Before roughing, the de-scaling water pressure is greater than 30Mpa;

(3) finish rolling de-scaling, finish rolling are rolling: use PC plate shape to control convexity≤100 μ m, planeness≤50I; Finish rolling reduces temperature drop, guarantees roll speed, and finishing temperature is controlled at more than 740 ℃; Before finish rolling, the de-scaling water pressure is greater than 30MPa;

(4) laminar flow is cooling: enter the laminar flow cooling section after finish rolling, cooling rate is controlled at 10～15 ℃/s, and 5 meters of steel heads of band are not cooling, and the limit section of the cold roller-way of the capable layer of open side spirt purges;

(5) reeling machine batches: the cooling complete reeling machine that enters batches rolling, 650～700 ℃ of coiling temperatures;

(6) concentrate the cooling in heap operation: batch complete rear concentrated stacking, guarantee near the steel plate soaking time Ar1 temperature, make cemetite lamellae attenuation in the perlite after Cooling Austenite Transformation, become broken and part spheroidizing, realize the material on-lining soften.

Beneficial effect of the present invention: the product elongation after fracture of producing obviously rises, product hardness has reduced 7.2-21%, and in its tissue, ratio of ferrite accounts for more than 60%, the suitable alligatoring of ferrite crystal grain, pearlite colony is small and scattered, the cemetite lamellae attenuation in perlite, the broken and part spheroidizing of change.Owing to having lower hardness and higher plasticity, can exempt rolling annealing operation afterwards, reach the purpose of on-lining soften.

Embodiment

The present invention will be further described by the following examples.

Embodiment 1: the qualified molten steel of steel mill's refining, and continuous casting becomes the 72*1500mm slab, and chemical composition is C:0.48%, Si:0.22%, Mn:0.70%, P:0.012%, S:0.007%, Als:0.020%, surplus is Fe; Continuously cast bloom adds thermal recovery 230m tunnel heating, 1080 ℃ of Heating temperatures, steel billet is come out of the stove and is entered 2 roughing mills by the roughing de-scaling, roughing total reduction 65%, roughing is cooled to 830 ℃ by intercooling, enters 5 finishing mills and be rolled after the finish rolling de-scaling, finished product thickness 5.0mm, enter immediately the laminar flow cooling section after finish rolling is completed and be cooled to 680 ± 20 ℃ and batch, cooling in heap after rolling.Chemical composition is listed in table 1, and processing parameter is listed in table 2, and finished product mechanical property and hardness see Table 3.

Embodiment 2: the qualified molten steel of steel mill's refining, and continuous casting becomes the 72*1250mm slab, and chemical composition is C:0.49%, Si:0.20%, Mn:0.72%, P:0.010%, S:0.006%, Als:0.022%, surplus is Fe; Continuously cast bloom adds thermal recovery 230m tunnel heating, 1090 ℃ of Heating temperatures, steel billet is come out of the stove and is entered 2 roughing mills by the roughing de-scaling, roughing total reduction 65%, roughing is cooled to 840 ℃ by intercooling, enters 5 finishing mills and be rolled after the finish rolling de-scaling, finished product thickness 5.0mm, enter immediately the laminar flow cooling section after finish rolling is completed and be cooled to 680 ± 20 ℃ and batch, cooling in heap after rolling.Chemical composition is listed in table 1, and processing parameter is listed in table 2, and finished product mechanical property and hardness see Table 3.

Embodiment 3: the qualified molten steel of steel mill's refining, and continuous casting becomes the 72*1500mm slab, and chemical composition is C:0.51%, Si:0.25%, Mn:0.72%, P:0.010%, S:0.008%, Als:0.024%, surplus is Fe; Continuously cast bloom adds thermal recovery 230m tunnel heating, 1070 ℃ of Heating temperatures, steel billet is come out of the stove and is entered 2 roughing mills by the roughing de-scaling, roughing total reduction 65%, roughing is cooled to 810 ℃ by intercooling, enters 5 finishing mills and be rolled after the finish rolling de-scaling, finished product thickness 4.5mm, enter immediately the laminar flow cooling section after finish rolling is completed and be cooled to 680 ± 20 ℃ and batch, cooling in heap after rolling.Chemical composition is listed in table 1, and processing parameter is listed in table 2, and finished product mechanical property and hardness see Table 3.

Table 1

Table 2

Table 3

By the medium high carbon steel plate that the rolling technology of exempting to anneal is produced, in tissue, cementite has been realized the part spheroidizing, and steel plate hardness drops to 80-85HRB by the 93-105HRB of pair rolling.Fall reaches 7.2-21%.

Claims (3)

1. exempt from annealing type medium high carbon steel plate manufacturing process for one kind, it is characterized in that: comprise that process furnace heating, edge rolling, roughing de-scaling, roughing are rolling, intercooling,--the finish rolling de-scaling, finish rolling is rolling, laminar flow is cooling, reeling machine batches and concentrate the cooling in heap operation, described intercooling operation, after slab carries out the roughing rolling process, advance--before finish rolling de-scaling operation, by refrigerating unit, slab is carried out coolingly, the cooling power of refrigerating unit is cooled to below 840 ℃ slab.

2. a kind of annealing type medium high carbon steel plate manufacturing process of exempting from according to claim 1, it is characterized in that: described roughing rolling process: the roughing mill draft reaches more than 65%; Described finish rolling rolling process: finish rolling stage employing two-phase region is rolling or ferrite area is rolling, and finishing mill possesses the ability of high speed tandem rolling, and the logical steel second flow of finish rolling end frame is not less than 20m ²/ s.

3. a kind of annealing type medium high carbon steel plate manufacturing process of exempting from according to claim 1 and 2 is characterized in that:

(1) process furnace heating process: heating of plate blank is followed heating-soaking-insulation system, and 1000～1150 ℃ of Heating temperatures are incubated 1 hour, guarantees that heating of plate blank is even, and without obvious blackspot, on elongated direction, base cross direction, the temperature difference is no more than 30 ℃;

(2) edge rolling, roughing de-scaling, roughing are rolling: drop into side guide and edge rolling, rolling load 50～100t before roughing; Before roughing, the de-scaling water pressure is greater than 30Mpa;

(3) finish rolling de-scaling, finish rolling are rolling: use PC plate shape to control convexity≤100 μ m, planeness≤50I; Finish rolling reduces temperature drop, guarantees roll speed, and finishing temperature is controlled at more than 740 ℃; Before finish rolling, the de-scaling water pressure is greater than 30MPa;

(4) laminar flow is cooling: enter the laminar flow cooling section after finish rolling, cooling rate is controlled at 10～15 ℃/s, and 5 meters of steel heads of band are not cooling, and the limit section of the cold roller-way of the capable layer of open side spirt purges;

(5) reeling machine batches: the cooling complete reeling machine that enters batches rolling, 650～700 ℃ of coiling temperatures;

(6) concentrate the cooling in heap operation: batch complete rear concentrated stacking, guarantee near the steel plate soaking time Ar1 temperature, realize the material on-lining soften.