CN100476007C - CSP production process of steel for automobile crossbeam - Google Patents

Abstract

The production process of SCP for automobile crossbeam includes the steps of converter smelting, LF refining, continuous casting and rolling, coiling and product inspection. The steel of SCP for automobile crossbeam consists of C 0.16-0.20 wt%, Si 0.3-0.5 wt%, Mn 1.3-1.5 wt%, P not more than 0.015 wt%, S not more than 0.010 wt%, Ti 0.01-0.03 wt%, Als 0.020-0.035 wt%, N not more than 65 PPm. Compared with available technology, the present invention has the advantages of relatively low alloy content in the steel, easy control of the chemical comprise, short production process and low production cost.

Description

The CSP production technique of beam steel

Technical field:

The invention belongs to this technical field of CSP explained hereafter Hi-Stren steel, belong to this technical field of CSP production technique of hot rolling automotive frame steel especially.

Background technology:

Beam steel as the making of automotive frame, is a very important safe appliance on the automobile mainly.Automotive frame generally adopts the big beam slab impact briquetting of hot rolling.Because automotive type difference, rammed automotive frame are also different, and each factory's pressing equipment is different with technology, the crossbeam on the different automobile types requires also different to the mechanical property of big beam slab with punching performance like this.For example at present Chongqing red rock automobile is used for the 510MPa level crossbeam steel of punching press crossbeam, use hot-rolled sheet without the direct punching press crossbeam of anneal: all ftracture with the 16ML punching press, big beam slab of 09SiVL and the big beam slab stamping cracking of Baosteel B510L rate that usefulness is climbed steel are 4/11.Big beam slab of 09SiVL and the big beam slab of Baosteel B510L solve the stamping cracking problem substantially after anneal, but find phenomenon of rupture in use to be arranged and increased production cost.Now Chongqing red rock automobile factory crossbeam adopting process be through with 09SiVL and B510L annealing back impact briquetting, but the yield strength σ 0.2 of annealing afterwards drops to 325MPa by 370MPa; σ b drops to 480MPa by 520MPa, and processability improves palette intensity and reduces, and safety performance also reduces.

Big beam slab surface treatment and press tool lubricating condition when a principal element that influences beam steel impact briquetting performance is punching press, because each automobile factory's equipment is different with processing condition, for adapting to punching press condition separately, the processing of automobile factory before to the auto truck beam punching press is also different.At present main methods mainly contains before the beam steel punching press: 1, shot blasting on surface, 2, cleanup acid treatment 3, surface do not handle three kinds of direct band iron scale punching presses (group company of domestic only JAC adopts this technology).Surface friction condition difference during punching press under the different treatment condition, it is unusual difficulty that a kind of beam steel sheet material is satisfied punching press requirement under the different condition simultaneously.The particularly cold stamping shaped plasticity of this mechanical property to hot rolling beam steel sheet material itself proposes very high request.The big beam slab of each trade mark of 510MPa level of domestic existing market supply can not satisfy 3 punching press requirements under the condition simultaneously.

The production technique of present domestic Beam Steel Plate is to adopt the heavy slab hot rolling technology of traditional process, plate shape is good during for the plate shape that guarantees big beam slab and automobile factory's cutting stock, do not produce the warpage defective, the auto truck beam that factory such as Baosteel and Wuhan Iron and Steel Plant produces all adopts after the hot rolling rolling by once with the secondary equipment for straightening big beam slab being carried out straightening processing on the crosscut unit again, though satisfied big beam slab plate shape and dimension precision requirement, because the existence of aligning internal stress, in the use during blanking of automobile factory's slitting, small powder behind the slitting that has still has the lateral bending defective to exist, and has influenced material material rate of utilization.

Summary of the invention:

Technical problem to be solved by this invention provides a kind of steel for automobile crossbeam technology with excellent mechanical performances.

The technical scheme of technical solution problem of the present invention is: the CSP production technique of beam steel comprises converter operation, LF refining procedure, CSP continuous casting and rolling operation, coiling process, inspection after construction operation; The chemical weight Composition Control of beam steel is as follows: C:0.16～0.20%, Si:0.3～0.5%, Mn:1.3～1.5%, P: S≤0.015% :≤0.010%, Ti:0.01～0.03%, Als:0.020～0.035%, N≤65PPm.

Described CSP continuous casting and rolling operation CSP is: the CSP slab thickness is 70mm, pulling rate is 4.0-4.5m/min, Heating temperature is 1100～1150 ℃, de-scaling high pressure water pressure is 200/360bar, finishing temperature is 800～820 ℃, roll postcooling and adopt cooling+front end laminar flow refrigerative two ends controlled chilling pattern fast, cooling termination temperature is 720 ℃ fast, and laminar flow cooling back coiling temperature is 600～620 ℃.The rolling employing of CSP CVC ⁺With plate shape and the dimensional precision of PCFC control techniques with the card finished product.

This technology by the cold zone controlled rolling and the quick cooling after rolling that material product is organized is tiny and even, can reduce the banded structure rank in the steel simultaneously.Material has good plasticity when satisfying requirement of strength, be very beneficial for the punching press distortion of beam steel.The beam steel performance that adopts this explained hereafter is that yield strength is: 405～415MPa, and tensile strength is: 540～560MPa, unit elongation is: 30～32%, yield tensile ratio is: 0.74～0.76; M510L coiled sheet thickness and precision is: ± 0.10mm.

The present invention compared with prior art, the STEELMAKING PRODUCTION cost of alloy is lower, the stable easily control of chemical ingredients, adopt and omit the required traverse aligning operation in rolling back in the conventional heavy slab flow process in CSP abbreviated system and the production technique, have the low advantage of manufacturing cost, can satisfy the punching press requirement under the different automobile factorys different surface treatment.

Embodiment:

Non-limiting examples is as follows:

The used equipment of present embodiment is: 120 tons of converters, 120 tons of LF refinings, 2 stream CSP continuous castings, 7 frame tandem rollings.

The present invention detects with the hot-rolled steel sheet standard by the GB-3272 automotive frame.

Embodiment 1:

With blank process converter operation, the LF refining procedure, in the steel chemical weight Composition Control as follows: C:0.17%, Si:0.41%, Mn:1.38%, P:0.014%, S:0.0020%, Ti:0.015%, Als:0.020%, N:34.2PPm, slab thickness is 70mm, pulling rate is 4.2m/min, Heating temperature is 1150 ℃, de-scaling high pressure water pressure is 200/360bar, 820 ℃ of finishing temperatures, roll postcooling and adopt cooling+front end laminar flow refrigerative two ends controlled chilling pattern fast, sheet material after rolling is batched, its temperature is 620 ℃, the rolling employing of CSP CVC ⁺Control with PCFC.

The mechanical property of embodiment is as shown in table 1:

Table 1:

	Yield strength (MPa)	Tensile strength (MPa)	Unit elongation (%)	Yield tensile ratio	Thickness and precision (mm)
						Embodiment 1	415	560	30	0.75	6.0±0.04

Embodiment 2:

With blank process converter operation, the LF refining procedure, in the steel chemical weight Composition Control as follows: C:0.18%, Si:0.38%, Mn:1.36%, P:0.010%, S:0.0009%, Ti:0.018%, Als:0.032%, N:44PPm, slab thickness is 70mm, pulling rate is 4.3m/s, Heating temperature is 1130 ℃, de-scaling high pressure water pressure is 280/360bar, 800 ℃ of finishing temperatures, roll postcooling and adopt cooling+front end laminar flow refrigerative two ends controlled chilling pattern fast, sheet material after rolling is batched, its temperature is 620 ℃, CSP rolling employing CVC+ and PCFC control.

The mechanical property of embodiment 2 is as shown in table 1:

Table 2:

	Yield strength (MPa)	Tensile strength (MPa)	Unit elongation (%)	Yield tensile ratio	Thickness and precision (mm)
						Embodiment 2	405	550	32	0.74	8.0±0.05

Embodiment 3:

With blank process converter operation, the LF refining procedure, make in the steel chemical weight Composition Control as follows: C:0.20%, Si:0.5%, Mn:1.5%, P:0.011%, S:0.0013%, Ti:0.02%, Als:0.030%, N:0.0062PPm, slab thickness is 70mm, pulling rate is 4.5m/s, Heating temperature is 1140 ℃, de-scaling high pressure water pressure is 200/360bar, 810 ℃ of finishing temperatures, roll postcooling and adopt cooling+front end laminar flow refrigerative two ends controlled chilling pattern fast, sheet material after rolling is batched, its temperature is 610 ℃, CSP rolling employing CVC+ and PCFC control.

The mechanical property of embodiment 3 is as shown in table 1:

Table 3:

	Yield strength (MPa)	Tensile strength (MPa)	Unit elongation (%)	Yield tensile ratio	Thickness and precision (mm)
						Embodiment 2	410	540	31	0.76	6.0±0.04

Embodiment 1 is adopted in Chongqing red rock automobile factory: shot blasting on surface+omission annealing process punching engine crossbeam is all qualified, omits the preceding annealing process of conventional M510 beam steel punching press;

Embodiment 2 is used in Anhui China water chestnut automobile group: surface acid-washing+oiling punching press transport mixer longeron is all qualified;

Embodiment 3 is used usefulness in Anhui group of JAC: band iron scale punching press light truck longeron is all qualified.

Claims (1)

1, the CSP production technique of beam steel comprises converter operation, LF refining procedure, CSP continuous casting and rolling operation, coiling process, inspection after construction operation; It is characterized in that: the chemical weight Composition Control of beam steel is as follows: C:0.16～0.20%, Si:0.3～0.5%, Mn:1.3～1.5%, P :≤0.015%, S :≤0.010%, Ti:0.01～0.03%, Als:0.020～0.035%, N≤65PPm, CSP continuous casting and rolling operation CSP is: the CSP slab thickness is 70mm, pulling rate is 4.0-4.5m/s, Heating temperature is 1100～1150 ℃, de-scaling high pressure water pressure is 200/360bar, 800 ℃-820 ℃ of finishing temperatures, roll postcooling and adopt cooling+front end laminar flow refrigerative two ends controlled chilling pattern fast, cooling back temperature is 720 ℃ fast, 600～620 ℃ of coiling temperatures; CSP rolling employing CVC+ and PCFC control.