CN101880821B - Steel-aluminum compound hot rolled steel with tensile strength of 280MPa and production method thereof - Google Patents

Abstract

The invention relates to hot rolled steel for heat exchangers of automobiles and small air conditioners. The hot rolled steel comprises the following components by weight percentage: less than 0.0025% of C, less than 0.008% of Si, 0.18-0.23% of Mn, 0.0031-0.0046% of Al, not more than 0.014% of P, less than 0.06% of S, not more than 0.0025% of O and the balance of Fe and inevitable impurities. The production steps are as follows: carrying out desulfurization on molten iron; refining outside a furnace; carrying out continuous casting, and using a covering agent with 0.1% of C and argon for protecting pouring; heating a continuous casting slab to 1240-1260 DEG C; controlling the final rolling temperature of hot rolling to be 910-930 DEG C; and coiling and controlling the temperature to be 650-670 DEG C. The hot rolled steel can replace parts with high requirements on thermal conductivity, such as the heat exchangers of aluminum plates and the like used by the automobiles and the small air conditioners, the production cost is low, and the hot rolled steel can lead the rigidity of the heat exchanger to be high and ensure the stability of the shape and the size of the heat exchanger.

Description

Tensile strength is the steel-aluminum compound hot rolled steel and the working method of 280MPa level

Technical field

The present invention relates to heat exchanger and use steel, being particularly suited for the Ultra-low carbon of automobile and minitype air conditioner, ultralow aluminium, ultralow oxygen characteristic tensile strength is that the heat exchanger that 280MPa, unit elongation reach more than 56% is used HRS.

Background technology

Traditional steel-aluminium is compound with soft steel or ultra low-carbon steel, mainly has problems such as aluminium content height, oxygen level height, thereby causes steel-aluminium composite performance low, influences the normal use of material.

In the prior art, have and added the noble metal nickel element, steel-aluminium condensation material is also arranged, but its base steel select for use for high manganese or high copper content, deficiency is that cost is all higher, and production technique is comparatively complicated.

The patent No. is the Japanese documentation of JP 2005161383; It discloses a kind of sheet material is two-sided compound summary of the invention; Wherein the one side of sheet material is that steel-aluminium is compound, and another side is that steel-aluminium-zinc is compound, also contains zirconium or magnesium, nickel in its base steel; It is not enough, and the interpolation alloying element is more, and production cost is higher.

Summary of the invention

The objective of the invention is to overcome the higher deficiency of foregoing invention cost; A kind of Ultra-low carbon, ultralow aluminium, ultralow oxygen characteristic are provided; Having tensile strength is that 280MPa level, unit elongation reach more than 56%; And have high-ductility and good composite performance, cost reduces significantly, and can guarantee that the tensile strength of processing stability of the shape and size of heat exchanger is the steel-aluminum compound hot rolled steel and the working method of 280MPa level.

Realize the technical measures of above-mentioned purpose:

Tensile strength is the steel-aluminum compound hot rolled steel of 280MPa level, and its component and weight percent are following: C:＜0.0025%, and Si:＜0.008%; Mn:0.18～0.23%; Al:0.0031～0.0046%, P :≤0.014%, S:＜0.006%; O :≤0.0025%, all the other are Fe and unavoidable impurities.

It is: the weight percent of C is≤0.0018%.

Tensile strength is the working method of the steel-aluminum compound hot rolled steel of 280MPa level, its step:

1) molten iron is carried out desulfurization, the weight percent of control S is＜0.006%;

2) carry out external refining, control: the weight percent of C is＜0.0025%, and the weight percent of Al is 0.0031～0.0046%;

3) carry out continuous casting, in casting process, employing C weight percent is 0.1% insulating covering agent, and adopts argon for protecting pouring, and the flow control of its argon gas is at 11-13NM ³/ hour;

4) continuously cast bloom is heated, heating and temperature control is at 1240～1260 ℃;

5) carry out hot rolling, controlling its finishing temperature is 910～930 ℃;

6) batch, coiling temperature is controlled at 650～670 ℃.

The effect of each element and mechanism among the present invention

C: in the present invention, C is as control element, and its content is low more good more; Because the C atom is strengthened the tensile strength that significantly improves material through the gap, but also reduce material plasticity simultaneously, so C content is low more, the plasticity of material is high more, so it is controlled at＜0.0025%.

Si: in the present invention, Si is as control element, and its content is low more good more; Because Si forms SiO in steel ₂Deng non-metallic inclusion, reduce the plasticity of material, so Si content is low more, the plasticity of material is high more, so it is controlled at＜0.008%.

Mn: in the present invention, Mn is as effective element, in steel, improves the tensile strength of material through solution strengthening; Simultaneously, Mn can crystal grain thinning, reaches the refined crystalline strengthening effect; Gap strengthening phase ratio with the C atom; Refined crystalline strengthening is less to the plasticity influence of material, is the requirement of 280MPa according to tensile strength, and design Mn content is 0.18～0.23%.

Al: in the present invention, Al is as control element, and the Al content in the steel is low more good more; Because higher like Al content, the compound interface at steel and aluminium forms steel-aluminium frangible compounds easily, reduces the intensity of steel-aluminium composite bed; So Al content is low more good more, but Al content can not be low excessively, as deoxidant element; If Al content is low excessively, cause in the steel deoxidation insufficient easily, form Al ₂O ₃Nonmetal inclusion, the plasticity of reduction material is so be controlled at 0.0031～0.0046% with it.

Beneficial effect of the present invention is following:

The present invention replaces traditional aluminium alloy plate to make parts with high requirements on thermal conductivity such as heat exchanger, can significantly reduce product cost, improves the rigidity of heat exchanger, and can guarantee the stability of the shape and size of heat exchanger.

Description of drawings

Fig. 1 is a low power continuous casting billet structure of the present invention (photo)

The non-metallic inclusion of Fig. 2 material of the present invention (photo)

The metallographic structure of Fig. 3 material of the present invention (photo)

Embodiment

Be described in detail below

According to component of the present invention and weight percent: C:＜0.0025%, Si:＜0.008%, Mn:0.18～0.23%; Al:0.0031～0.0046%, P :≤0.014%, S:＜0.006%; O :≤0.0025%, all the other are Fe and unavoidable impurities, and

Working method:

1) molten iron is carried out desulfurization, the weight percent of control S is＜0.006%;

2) carry out external refining, control: the weight percent of C is＜0.0025%, and the weight percent of Al is 0.0031～0.0046%;

3) carry out continuous casting, in casting process, employing C weight percent is 0.1% insulating covering agent, and adopts argon for protecting pouring, and the flow control of its argon gas is at 11-13NM ³/ hour;

4) continuously cast bloom is heated, heating and temperature control is at 1240～1260 ℃;

5) carry out hot rolling, controlling its finishing temperature is 910～930 ℃;

6) batch, coiling temperature is controlled at 650～670 ℃.

Specifically describe with the tabulation mode:

Table 1 is component and the weight percent that each embodiment got;

Table 2 is the processing parameter of each embodiment;

Table 3 is the performance test results of each embodiment.

Table 1 various embodiments of the present invention chemical composition and wt%

Embodiment	C	Si	Mn	P	S	Al	O
								1	0.0011	0.0079	0.195	0.009	0.0044	0.0038	0.0018
2	0.0013	0.0065	0.200	0.014	0.0035	0.0040	0.0015
								3	0.0010	0.0050	0.180	0.012	0.0030	0.0034	0.0025
4	0.0017	0.0070	0.230	0.011	0.0050	0.0046	0.0020
								5	0.0018	0.0055	0.197	0.011	0.0044	0.0042	0.0023
6	0.0025	0.0030	0.187	0.013	0.0059	0.0031	0.0010

Table 2 is the processing parameter of each embodiment

The mechanical property of table 3 various embodiments of the present invention

The steel reel number	Thickness of slab mm	R p0.2 (MPa)	Rm (MPa)	A 80mm (％)
					1	4.0	190	280	56
2	4.0	180	280	56
					3	4.0	175	285	57
4	4.0	185	285	57
					5	4.0	180	285	59
6	4.0	185	285	56

Data can know that YIELD STRENGTH and tensile strength are respectively at 175～190MPa and 280～285MPa from table, and unit elongation has all reached the standard of material 56～59%, and especially unit elongation numerical value is high, has all satisfied user's requirement.

Claims (2)

1. tensile strength is the steel-aluminum compound hot rolled steel of 280MPa level, and its component and weight percent are: C:＜0.0025%, and Si:＜0.008%; Mn:0.195～0.23%; Al:0.0031～0.0046%, P :≤0.014%, S:＜0.006%; O :≤0.0025%, all the other are Fe and unavoidable impurities.

2. the described tensile strength of production claim 1 is the method for the steel-aluminum compound hot rolled steel of 280MPa level, its step:

1) molten iron is carried out desulfurization, and the weight percent of control S is＜0.006%;

2) carry out external refining, and control: the weight percent of C is＜0.0025%, and the weight percent of Al is 0.0031～0.0046%;

3) carry out continuous casting, in casting process, the weight percent that adopts C is 0.1% insulating covering agent, and adopts argon for protecting pouring, and the flow control of argon gas is at 11-13NM ³/ hour;

4) continuously cast bloom is heated, heating and temperature control is at 1240～1260 ℃;

5) carry out hot rolling, controlling its finishing temperature is 915～930 ℃;

6) batch, coiling temperature is controlled at 655～670 ℃.

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