CN101139683A

CN101139683A - Air corrosion resistant steel

Info

Publication number: CN101139683A
Application number: CNA2007101216376A
Authority: CN
Inventors: 王向东; 刘清友; 杨红梅; 陈小平; 汪兵; 贾书君
Original assignee: Central Iron and Steel Research Institute
Current assignee: Central Iron and Steel Research Institute
Priority date: 2007-09-12
Filing date: 2007-09-12
Publication date: 2008-03-12
Anticipated expiration: 2027-09-12
Also published as: CN100480413C

Abstract

The invention belongs to the field of low-alloy steel, in particular relates to a steel resistant to atmospheric corrosion. The chemical components (wt per cent) of the steel are that: C is of no more than 0.08 per cent, Si is of 0.10 to 0.30 per cent, Mn is of 0.40 to 0.60 per cent, S is of no more than 0.01 per cent, P is of 0.03 to 0.13 per cent, Nb is of 0.02 to 0.03 per cent and RE is of 0.02 to 0.15 per cent, the remainder are iron and unavoidable foreign matters. Compared with the prior art, the alloy has simple elements, low cost, excellent anti-corrosion performance, high strength and better low-temperature impact toughness.

Description

Weather resisting steel

Technical field

The invention belongs to the low alloy steel field, particularly a kind of weather resisting steel.

Background technology

Usually, carbon steel and low alloy steel with good mechanical property and lower price are the structured materials of using always, but these steel are easy to generate metallic corrosion in atmospheric environment, have not only caused metal loss, and have increased the workload of making processing and maintain and replace.

At present, in order to improve the erosion resistance of carbon steel and low alloy steel, generally adopt the method for in steel, adding the different-alloy element to improve the atmospheric corrosion resistance of steel.It is generally acknowledged that Cu, P are the optimal alloying elements of weathering steel, add the COR-TEN A series of nickel, chromium and based on the serial weather resisting steel of the COR-TEN B of Cr, Mn, Cu as high phosphorus, the copper of U.S. development, and the 09CuPTiRE class weathering steel of China Wuhan Iron and Steel Company development etc., all without exception be main adding elements with Cu, P.

" atmospheric corrosion resistance and high temperature resistance crackle steel (the Weatherand high temp cracking resistant steel) " that Japanese Patent (18.09.80) J51071-817C22C38/42 introduces, its chemical ingredients (wt%) is C≤0.08%, Si≤0.75%, Mn:10～20%, P:0.05～0.15%, Cu:0.15～0.60%, Cr:0.10～0.15%, Ni:0.15～1.0%, Al＜0.10%, and surplus is Fe and unavoidable impurities.

China Patent No. 85108118A has introduced a kind of Weather-resistant low alloy steel, its chemical ingredients is C≤0.12%, Si:0.20～0.75%, Mn:0.20～0.70%, P:0.06～0.15%, Cu:0.20～0.50%, V:0.02～0.12%, Xt≤0.20%, S≤0.04%, and surplus is Fe and unavoidable impurities.

U.S. USS standard C or-Ten " B " regulation weathering steel composition (%) is: C:0.10～0.19, Si:0.15～0.30, Mn:0.90～1.25, S≤0.05, P≤0.04, Cu:0.25～0.40, Cr:0.40～0.65, V:0.02～0.10, surplus are Fe and unavoidable impurities.

Above-mentioned steel grade because phosphorus, copper content are higher in the composition, and contains chromium, nickel alloy element, improved the ability of the atmospheric corrosion resistance of steel, but high phosphorus has also brought low temperature brittleness simultaneously, and high-copper has brought hot rolling be full of cracks and bending cracks etc., and promptly plasticity and toughness descend; In addition, because alloy total amount height, phosphorus content and carbon content are low, and the price of steel is improved.

Summary of the invention

The object of the present invention is to provide a kind of alloying element simple, cost is low, and has excellent anti-corrosion performance, and intensity is higher, good low-temperature impelling strength weather resisting steel.

According to above-mentioned purpose, overall technical architecture of the present invention is that (carbon structural steel chemical ingredients (wt%) is: P＜0.045% on the basis of carbon structural steel chemical ingredients, S＜0.045%, Cu＜0.3%, Si:0.12～0.30%, Mn:0.30～0.60%), the upper limit of reduction S content, improve the lower limit of P content, and add rare earth elements RE.

The principle of work of above-mentioned overall technical architecture is:

Result of study shows that phosphorus and rare earth are the very outstanding alloying elements of solidity to corrosion effect, and under the condition of atomospheric corrosion, the phosphorus in the steel is the anode depolarizer, and rare earth element is a cathode deposition type inhibiter.Alloying element P and RE can promote the formation of steel surface-stable corrosion product after adding, rusty scale densification more in making, thereby the corrosion resistance nature of raising steel.

In addition, phosphorus plays the effect of solution strengthening in steel, improves the intensity of steel.But in steel, add the form of rare earth cleaning molten steel and control inclusion, make it nodularization, thereby improve the plasticity and the corrosion resisting property of steel.The adding of alloying element P and RE is improved the over-all properties of steel.

Principle of work according to above-mentioned purpose and whole technical scheme: concrete technical scheme of the present invention is: the chemical composition of this steel (wt%) is: C≤0.08%, Si 0.10～0.30%, Mn 0.40～0.60%, S≤0.01%, P 0.03～0.13%, Nb 0.02～0.03% and RE 0.02～0.15%, surplus is the Fe unavoidable impurities.

The effect of above-mentioned each element and proportioning are according to as follows:

C is very important element to the intensity of steel of the present invention, but C content too much has detrimentally affect to corrosion resisting property, is the upper limit of C content so limit 0.08%.

Si is the element that adds for steel is carried out deoxidation, the oxygen level that reduces in the steel can play the effect that purifies steel, an amount of adding Si element can also improve the intensity of steel simultaneously, so its content should reach more than 0.10%, but the Si too high levels also has disadvantageous effect to corrosion resisting property, stipulates that high-content is 0.30%.

Mn is limited to 0.30% being indispensable element aspect the toughness of guaranteeing steel and the intensity under it; But Mn content too much easily with steel in S formation MnS be mingled with solidity to corrosion unfavorablely, be limited to 0.50% on the Mn of Guangdong.

S is very big to the corrosion resisting property influence of steel, and the existence that the Sization thing in the steel is mingled with makes between ferrous materials and the Sization thing and forms potential difference, brings out the corrosion of steel in corrosive environment, so the content of S is controlled at below 0.01%.

P is the favourable element of antagonism atomospheric corrosion performance, P is the anode depolarizer, can promote the uniform dissolution of steel in the steel behind the adding P, helps to form uniform alpha-feooh rusty scale on the steel surface, but too high P content has infringement to the toughness of steel, so the P upper content limit is controlled at 0.13%.

Nb has stronger refined crystalline strengthening effect and precipitation strength effect, and Nb content is crossed low or too high all undesirable to Effect on Performance, so Nb is controlled between the 0.02-0.03% scope.

RE: rare earth element has inclusion modification and purifies the effect of steel, inclusion after the sex change, particularly hydrolysis takes place in rare-earth sulfide in corrosion process, changes steel surface microcell pH value, corrosion there is restraining effect, content of rare earth surpasses certain value just effect, so its content should reach more than 0.10%, but the too high meeting of content of rare earth rolls up second phase amount in the steel, mechanical property there is detrimentally affect, so the content of rare earth upper limit is controlled at 0.15%.

Employing of the present invention and prior art be preparation method like the institute mutually:

The invention steel adopts 50 kilograms of vacuum ovens to smelt, and prepares burden and all adds rare earth to guarantee the rare earth recovery rate when watering ingot, adopts cooling controlling and rolling controlling process to obtain fine grain structure to improve mechanical property.

The present invention compared with prior art alloying element is simple, and cost is low, and has excellent anti-corrosion performance, and intensity is higher, the advantage of good low-temperature impelling strength.Above-mentioned advantage is specific as follows:

(1) chemical ingredients of the present invention is simple, so technology is easy to stablize, its cost only is the straight carbon steel level, but its atmospheric corrosion resistance is far superior to straight carbon steel.

(2) the present invention adopts on the high phosphorus basis and adds rare earth, and when obtaining preferably erosion resistance, its intensity is higher, and has good low-temperature impelling strength, its R _EL〉=300MPa, A _Kv2/ J (40 ℃) 〉=30J.

Description of drawings

Accompanying drawing 1 is the metallographic structure figure of atmospheric corrosion resistance three stove steel of the present invention.

Accompanying drawing 2 is the comparison diagram of steel of the present invention and compared steel simulation atmospheric corrosion test.

In above-mentioned accompanying drawing 2, X-coordinate is a test period, and unit is h; Ordinate zou is a corrosion rate, and unit is g/m ²H.

Embodiment

According to chemical ingredients scope of the present invention, three these corrosion-resistant steels of stove have been smelted altogether.Concrete chemical ingredients is as shown in table 1.Three stove steel are through casting, and the sampling of rolling back, and Fig. 1 is seen in steel metallographic structure of the present invention.Carry out mechanicl test according to GB GB/T229-1994, test-results is listed in table 2.Simultaneously three stove steel have been carried out the laboratory simulation atmospheric corrosion test, in order to contrast, the sample that also will contrast grade of steel SS400 carbon steel and phosphorous 0.12% carbon steel has carried out the simulation atmospheric corrosion test under the same terms of laboratory.Test-results is seen accompanying drawing 2.In above-mentioned tabulation, 1-3# is the embodiment of the invention, and 4-5# is prior art compared steel SS400 carbon steel and phosphorous 0.12% carbon steel.By accompanying drawing 2 as seen, in the Total Test process, the corrosion rate of steel of the present invention is well below compared steel, and therefore, the present invention has excellent atmospheric corrosion resistance.By accompanying drawing 2 visible another feature, promptly all to simulate in the atomospheric corrosion process, the increase of the erosion resistance content of rare earth of steel of the present invention slightly improves.

Table 1 embodiment of the invention is compared with the prior art steel chemical composition contrast table (wt%)

Sequence number	Grade of steel	C	Si	Mn	P	S	Nb	Re
Sequence number	Grade of steel	C	Si	Mn	P	S	Nb	Re	1	91-3	0.071	0.12	0.42	0.031	0.0066	0.021	0.026
2	84-3	0.053	0.22	0.53	0.078	0.0096	0.023	0.096	1	91-3	0.071	0.12	0.42	0.031	0.0066	0.021	0.026
2	84-3	0.053	0.22	0.53	0.078	0.0096	0.023	0.096	3	84-1	0.053	0.29	0.60	0.13	0.0096	0.020	0.150
4	The SS400 carbon steel	O.133	0.211	0.342	0.012	0.0056	-	-	3	84-1	0.053	0.29	0.60	0.13	0.0096	0.020	0.150
4	The SS400 carbon steel	O.133	0.211	0.342	0.012	0.0056	-	-	5	Phosphorous 0.12 % carbon steel	0.122	0.210	1.050	0.122	0.0155	-	-

Table 2 embodiment of the invention is compared with the prior art the mechanical property contrast table of steel

Sequence number	Grade of steel	R _eL/MPa	R _m/MPa	A/％	A _kv2/J(-40℃)
Sequence number	Grade of steel	R _eL/MPa	R _m/MPa	A/％	A _kv2/J(-40℃)	1	91-3	335	467	36.3	31.5
2	84-3	295	432	34.2	35.5	1	91-3	335	467	36.3	31.5
2	84-3	295	432	34.2	35.5	3	84-1	308	413	31.3	32.5
4	The SS400 carbon steel	235	398	27.3	21	3	84-1	308	413	31.3	32.5
4	The SS400 carbon steel	235	398	27.3	21	5	Phosphorous 0.12% carbon steel	292	479	31.4	3

Claims

1. weather resisting steel, the chemical composition (wt%) that it is characterized in that steel is: C≤0.08%, Si 0.10～0.30%, Mn 0.40～0.60%, S≤0.01%, P 0.03～0.13%, Nb 0.02～0.03% and RE 0.02～0.15%, surplus is iron and unavoidable impurities.