CN101880820A - Steel-aluminum compound hot rolled steel with tensile strength of 310MPa and production method thereof - Google Patents

Abstract

The invention relates to hot rolled steel for radiators of central air conditioners. The hot rolled steel comprises the following components by weight percentage: 0.004-0.006% of C, less than 0.015% of Si, 0.25-0.35% of Mn, 0.0021-0.0030% of Al, not more than 0.022% of P, less than 0.006% of S, not more than 0.003% of O and the balance of Fe and inevitable impurities. The steps are as follows: carrying out desulfurization on molten iron; refining outside a furnace; carrying out continuous casting, and adopting a covering agent with 0.1% of C and argon for protecting pouring; heating a continuous casting slab to 1220-1238 DEG C; controlling the final rolling temperature of hot rolling to be 890-908 DEG C; and coiling and controlling the temperature to be 630-649 DEG C. The hot rolled steel can replace an aluminum alloy plate heat exchanger of the central air conditioner, 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 production method of 310MPa level

Technical field

The present invention relates to the heat exchanger steel, being particularly suited for the Ultra-low carbon of central air-conditioning, ultralow aluminium, ultralow oxygen characteristic tensile strength is that 310MPa, unit elongation reach the parts with high requirements on thermal conductivity hot-rolled steels such as heat exchanger more than 46%.

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, another side is that steel-aluminium-zinc is compound, also contain 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 above-mentioned deficiency, a kind of Ultra-low carbon, ultralow aluminium, ultralow oxygen characteristic are provided, having tensile strength is that 310MPa level, unit elongation reach more than 46%, 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 production method of 310MPa level.

Realize the technical measures of above-mentioned purpose:

Tensile strength is the steel-aluminum compound hot rolled steel of 310MPa level, its component and weight percent are: C:0.004～0.006%, Si:＜0.015%, Mn:0.25～0.35%, Al:0.0021～0.003%, P :≤0.022%, S:＜0.006%, O :≤0.003%, all the other are Fe and unavoidable impurities.

It is: the weight percent of C is 0.005～0.0055%.

It is: the weight percent of Mn is 0.28～0.33%.

Production tensile strength is the method for the steel-aluminum compound hot rolled steel of 310Mpa level, its step:

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

2) carry out external refining, the weight percent of control C is 0.004～0.006%, and the weight percent of Al is 0.0021～0.003%;

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 its argon gas is at 11-13NM ³/ hour;

4) continuously cast bloom is heated, heating and temperature control is at 1220～1238 ℃;

5) carry out hot rolling, controlling its finishing temperature is 890～908 ℃;

6) batch, coiling temperature is controlled at 630～649 ℃.

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 by the gap, but also reduce material plasticity simultaneously, the plasticity of compound material and intensity are so be controlled at 0.004～0.006% with it.

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＜0.0015%.

Mn: in the present invention, Mn is as effective element, in steel, improve the tensile strength of material by 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 310MPa according to tensile strength, and design Mn content is 0.25～0.35%.

Al: in the present invention, Al is as control element, and the Al content in the steel is low more good more; Because Al content is higher, 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 0.0021～0.0030% with it.

Beneficial effect of the present invention is as follows:

The present invention replaces traditional aluminium alloy plate to make the parts with high requirements on thermal conductivity such as heat exchanger of central air-conditioning, 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

Accompanying drawing is the metallographic structure figure of material of the present invention

Embodiment

Be described in detail below

As follows according to component of the present invention and weight percent: component and weight percent are as follows: C:0.004～0.006%, Si:＜0.015%, Mn:0.25～0.35%, Al:0.0021～0.0030%, P :≤0.022%, S:＜0.006%, O :≤0.003%, all the other are Fe and unavoidable impurities.And

Production 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 0.004～0.006%, and the weight percent of Al is 0.0021～0.003%;

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 its argon gas is at 11-13NM ³/ hour;

4) continuously cast bloom is heated, heating and temperature control is at 1220～1238 ℃;

5) carry out hot rolling, controlling its finishing temperature is 890～908 ℃;

6) batch, coiling temperature is controlled at 630～649 ℃.

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.

The chemical ingredients of table 1 various embodiments of the present invention (wt%)

Embodiment	??C	??Si	??Mn	??P	??S	??Al	??O
								??1	??0.0046	??0.013	??0.27	??0.021	??0.0044	??0.0023	??0.0018
??2	??0.0052	??0.010	??0.30	??0.022	??0.0035	??0.0028	??0.0015
								??3	??0.0040	??0.014	??0.25	??0.015	??0.0030	??0.0026	??0.0030
??4	??0.0050	??0.015	??0.35	??0.011	??0.0050	??0.0030	??0.0020
								??5	??0.0055	??0.009	??0.28	??0.009	??0.0044	??0.0026	??0.0023
??6	??0.0060	??0.012	??0.33	??0.013	??0.0060	??0.0021	??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)	??R m??(MPa)	??A 80mm??(％)
					??1	??4.0	??195	??310	??46
??2	??4.0	??215	??310	??48
					??3	??4.0	??220	??310	??47

The steel reel number	Thickness of slab mm	??R p0.2??(MPa)	??R m??(MPa)	??A 80mm??(％)
					??4	??4.0	??210	??310	??47
??5	??4.0	??220	??310	??48
					??6	??4.0	??200	??310	??47

As can be known from the table data, YIELD STRENGTH and tensile strength are respectively at 195～220MPa and 310MPa, and unit elongation has all reached the standard of material 46～48%, and especially unit elongation numerical value height has all satisfied user's requirement.

Claims (4)

1. tensile strength is the steel-aluminum compound hot rolled steel of 310MPa level, its component and weight percent are as follows: C:0.004～0.006%, Si:＜0.015%, Mn:0.25～0.35%, Al:0.0021～0.003%, P :≤0.022%, S:＜0.006%, O :≤0.003%, all the other are Fe and unavoidable impurities.

2. tensile strength as claimed in claim 1 is the steel-aluminum compound hot rolled steel of 310MPa level, it is characterized in that: the weight percent of C is 0.005～0.0055%.

3. tensile strength as claimed in claim 1 is the steel-aluminum compound hot rolled steel of 310MPa level, it is characterized in that: the weight percent of Mn is 0.28～0.33%.

4. the described tensile strength of production claim 1 is the method for the steel-aluminum compound hot rolled steel of 310MPa 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 0.004～0.006%, and the weight percent of Al is 0.0021～0.003%;

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 its argon gas is at 11-13NM ³/ hour;

4) continuously cast bloom is heated, heating and temperature control is at 1220～1238 ℃;

5) carry out hot rolling, controlling its finishing temperature is 890～908 ℃;

6) batch, coiling temperature is controlled at 630～649 ℃.