CN1869270A - Superhigh strength steel of atmospheric corrosion resisting and its manufacturing method - Google Patents

Abstract

The invention relates to super high intension anti atmospheric corrosion steel casting in air. The yield strength is over 230000psi, tensile strength is over 250000psi, and the tensile stretch is about 6%. It contains at least one constituent from V, W, N and the mixture. In another optimized selecting project, the content of C is 0.16-0.23wt%, Si content is 0.2-1.5wt%, Cr content is 2-5wt%, Cu content is 0.2-2wt%, Mo content is 0.8-3wt%, Ni content is 7-12wt%, Co content is 13-17wt%, and the rest is Fe.

Description

Superhigh strength steel of atmospheric corrosion resisting and manufacture method thereof

Technical field

The present invention relates to ultrahigh-strength steel, more specifically, relate to the ultrahigh-strength steel that can cast in air, it has the character of improved intensity, ductility, toughness and erosion resistance aspect compared with traditional ultrahigh-strength steel.

Background technology

There are many defectives in traditional ultrahigh-strength steel.For example, most martensite and maraging steel be atmospheric corrosion resistance not, especially in castingprocesses.Control the existence of unwanted calking and extraneous element for strictness, adopt highly purified starting material, under vacuum condition, carry out the fusion of traditional maraging steel.

The superstrength precipitation hardening steel of maraging steel and other type is in inert environments; under vacuum condition, carry out fusion and cast (pour); thereby protection is used to make the essential and very highly active element of this class steel, as titanium and aluminium, it is not exposed in the atmosphere.In fusion and pouring technology, on purpose avoid being exposed to atmosphere, its objective is to prevent active element generation oxidizing reaction.Know that the existence of the active element of oxidation state has seriously reduced the mechanical properties of wanting of resulting steel.

Yet this vacuum fusion and cast are expensive.In addition, many traditional ultrahigh-strength steel must carry out repeatedly vacuum fusion and cast, to obtain the purity of aspiration level.In case finished fusion and pouring technology, steel must experience important forging processing and the mechanical properties of acquisition expectation.Owing to require to forge processing, steel manufacturers must have and use progressive die to obtain the shape and the mechanical properties of expectation, and this has further increased makes expectation required cost and the time of product made from steel.And many traditional ultrahigh-strength steel need chromium plating or cadmium plating in great majority are used, protect with the non-corrosibility that certain level is provided, thus protection alloy non-corrosive.

Traditional Ultra-High Strength Maraging Steel generally includes alloying element listed in the following table 1 (by weight percentage):

Table 1

Maraging200	18Ni	3.3Mo	8.5Co	0.2Ti	0.1Al	Balance Fe
							Maraging250	18Ni	5Mo	8.5Co	0.4Ti	0.1Al	Balance Fe
Maraging300	18Ni	5Mo	9Co	0.7Ti	0.1Al	Balance Fe
							18Ni (vacuum casting)	17Ni	4.6Mo	10Co	0.2Ti	0.3Al	Balance Fe
Cobalt Free 250	18.5 Ni	3Mo		0.7 Ti	0.1Al	Balance Fe

Titanium and aluminium are to make the necessary composition that adopts in the maraging steel, its objective is the character that makes the steel that obtains have increased intensity and hardness.Yet, adopt any steel capital that titanium and aluminium makes can not fusion in air (as explained above), reason is the compound that they are easy to form embrittlement.Therefore, the ultrahigh-strength steel that adopts titanium and aluminium to form must carry out vacuum fusion and cast.

And, traditional martensite ultrahigh-strength steel, as AISI 4340, the tenacity levels deficiency of H11 and 300M, corrosion-resistant to atmospheric elements, thereby can not be used in many toughness that both required to have desirable level, require again to have in the high-strength steel application scenario of erosion resistance to a certain degree, for example can not use in the application scenario that exposes out of doors.In addition, make the steel that obtains be difficult to welding usually for making the alloy that these steel use, the steel as foundry goods of gained is compared with forged counterpart, and mechanical properties is relatively poor.

On the other hand, the maraging steel of known superstrength has good toughness and weldability character.Yet as mentioned above, maraging steel is to atomospheric corrosion and relevant stress corrosion fracture sensitivity.The cost that obtains these steel also is very expensive.

As above sketched, the most common technology of making Ultra-High Strength Maraging Steel is by two or three road smelting process, and it comprises at least one vacuum fusion/concise circulation.Usually forge after fusion/concise circulation, and be rolled into sheet material or bar.By forging processing, maraging steel obtains optimal properties.Although known maraging steel is cast the product made from steel that has obtained to have suitable intensity, casting becomes the netted ductility relatively poor (forgedly comparing with the counterpart of mechanical workout with it) that causes, and is as shown in table 2 below.

Table 2

Alloy	Yield strength	Tensile strength	Elongation	Reduce %
						PSI	PSI	％	(ductility)
Maraging250
					(forged)	247,000	260,000	8	55
Maraging250
					(casting)	242,102	261,233	5.8	10

Therefore need develop with above-mentioned those traditional ultrahigh-strength steel and compare, the new ultrahigh-strength steel that improves to some extent at the bulk properties aspect intensity, toughness, ductility and anti-atmospheric corrosion or the erosion resistance.Also wish need not to make the new ultrahigh-strength steel of this class in the mode that allows in air, to cast under the condition of expensive and vacuum fusion consuming time and pouring technology.

The general introduction of preferred embodiment

According to an aspect of the present invention, provide a kind of by combination C, Si, Cr, Cu, Mo, Ni, Co and Fe make, (air-cast) superhigh strength steel of atmospheric corrosion resisting of casting in the air, and wherein the yield strength of this steel is greater than about 230,000psi, tensile strength is greater than about 250,000psi, and elongation is greater than about 6%.In a kind of embodiment preferred, the superhigh strength steel of atmospheric corrosion resisting of casting in this air comprises and is selected from V, W, at least a composition of N and its mixture.In another kind of embodiment preferred, the content of C is about 0.16 to 0.23wt%, the content of Si is about 0.2 to 1.5wt%, the content of Cr is about 2 to 5wt%, the content of Cu is about 0.2 to 2wt%, and the content of Mo is about 0.8 to 3wt%, and the content of Ni is about 7 to 12wt%, the content of Co is about 13 to 17wt%, and Fe exists with surplus.In one embodiment, the superhigh strength steel of atmospheric corrosion resisting of casting in this air is substantially free of Al and Ti.

According to a further aspect in the invention, superhigh strength steel of atmospheric corrosion resisting is provided, it is substantially by about C of 0.16 to 0.23wt%, about Si of 0.2 to 1.5wt%, about Cr of 2 to 5wt%, about Cu of 0.2 to 2wt%, about Mo of 0.8 to 3wt%, about Ni of 7 to 12wt%, about Co of 13 to 17wt%, and the Fe of surplus forms.In a kind of embodiment preferred, this superhigh strength steel of atmospheric corrosion resisting comprises and is selected from V, W, at least a composition of N and its mixture.In one embodiment, the yield strength of this superhigh strength steel of atmospheric corrosion resisting is greater than about 230,000psi, and tensile strength is greater than about 250,000psi, and elongation is greater than about 6%.

According to another aspect of the invention, provide superhigh strength steel of atmospheric corrosion resisting, it comprises 0.16 to 0.23wt% C, about Si of 0.2 to 1.5wt%, about Cr of 2 to 5wt%, about Cu of 0.2 to 2wt%, about Mo of 0.8 to 3wt%, about Ni of 7 to 12wt%, about Co of 13 to 17wt% mostly is the V of 2wt% most, mostly is the W of 2wt% most, mostly be most the N of 0.4wt%, and the Fe of surplus forms.In a kind of embodiment preferred, the yield strength of superhigh strength steel of atmospheric corrosion resisting is greater than about 230,000psi, and tensile strength is greater than about 250,000psi, and elongation is greater than about 6%.

In accordance with a further aspect of the present invention, the foundry goods of being made by the steel of anti-atmospheric corrosion the (casting) is provided, it prepares according to the following step: about 1, the temperature that 900  are above and be higher than about 14, under the pressure of 000psi, the cast member of being made by this steel of anti-atmospheric corrosion the (cast part) is carried out about 3 to 5 hours hot-isostatic pressing (hot isostatic pressing) handle; Under the temperature more than about 2,000  cast member being carried out about 1 to 6 hour homogenizing handles; In the temperature range of about 2,100 , cast member is carried out about 1 to 4 hour sosoloid thermal treatment (solution heattreating), cool to room temperature then at about 1,600 ; Cooled off about 1 to 8 hour under the temperature that is lower than pact-50  by the freezing cast member that makes; And cast member is carried out about 4 to about 5 hours burin-in process between the temperature of about 1,000  at about 800 .In a kind of embodiment preferred, the formation step of this foundry goods is: make up about C of 0.16 to 0.23wt%, about Si of 0.2 to 1.5wt%, about Cr of 2 to 5wt%, about Cu of 0.2 to 2wt%, about Mo of 0.8 to 3wt%, about Ni of 7 to 12wt%, about Co of 13 to 17wt%, and the Fe of surplus; The composition of fusion combination and form the steel reinforced concrete of anti-atmospheric corrosion compound; And cast this steel reinforced concrete of anti-atmospheric corrosion compound and form cast member.In another embodiment, during the aforesaid combination step, also adding is selected from V, W, one or more compositions of N and its mixture.In another embodiment, the step of described fusion and cast is carried out in air ambient.In another embodiment, through after the described burin-in process step, the yield strength of described cast member is greater than about 230,000psi, and tensile strength is greater than about 250,000psi, and elongation is greater than about 6%.

According to a further aspect in the invention, provide the method for making cast member by the steel of anti-the atmospheric corrosion.This method comprises the following steps: by making up about C of 0.16 to 0.23wt%, about Si of 0.2 to 1.5wt%, about Cr of 2 to 5wt%, about Cu of 0.2 to 2wt%, about Mo of 0.8 to 3wt%, about Ni of 7 to 12wt%, about Co of 13 to 17wt%, and the Fe of surplus; Thereby the composition of fusion combination forms the steel reinforced concrete of anti-atmospheric corrosion compound; And cast this steel reinforced concrete of anti-atmospheric corrosion compound and form cast member.In one embodiment, the step of described fusion and cast is carried out in air ambient.

Description of Preferred Embodiments

The present invention relates to superhigh strength steel of atmospheric corrosion resisting (hereinafter referred to as " steel of anti-the atmospheric corrosion ") and its manufacture method.The steel of anti-atmospheric corrosion the of the present invention generally includes cobalt, nickel, chromium, copper, molybdenum, silicon and carbon as the basic alloy element.Be used to form the specific composition of the alloying constituent of the present invention's steel of anti-the atmospheric corrosion, and be used for processing this anti-atmospheric corrosion Heat Treatment Of Steel and provide and can cast at air, have the steel that improves to some extent aspect intensity, ductility, toughness and the resistance to atmospheric corrosion compared with traditional ultrahigh-strength steel.If desired, the steel of anti-atmospheric corrosion the of the present invention can carry out vacuum fusion and directly be poured in the mould (investment cast) or make ingot casting, and it is forged subsequently, with its toughness of further raising and fatigue characteristic.

When the key feature of the present invention's steel of anti-the atmospheric corrosion is to realize these improvement in performance, on purpose avoid adopting the ability of active element such as titanium and/or aluminium.In make typical maraging steel in order to obtain hardness, very common to the use of these elements.Therefore, it is beyond thought and wonderful on purpose avoiding adopting the ability of these elements when the steel with high rigidity is provided, and formerly thinks to realize.

In order to make the steel of anti-the atmospheric corrosion can fusion in air, avoid using these active elements wittingly.The property judged ground is selected other alloying element and/or the whole machine balancing of the alloying constituent that is used to make the steel of anti-the atmospheric corrosion is regulated, thereby obtains the comprehensive mechanical character of expectation.These elements are carried out diplomatic substituting, and this has been avoided carrying out a plurality of fusions and cast circulation in inactive environment, thereby can be to be lower-cost, and the mode of more free efficient forms the steel of anti-the atmospheric corrosion again.

The steel of anti-the atmospheric corrosion can be formed by following atomic element: Fe, Ni, Mo, Co, Cr, C, Si and Cu.As mentioned above, the steel of the anti-atmospheric corrosion the of the present invention key feature that is different from traditional ultrahigh-strength steel such as maraging steel etc. is on purpose to avoid using active element titanium and aluminium.

The ladle of anti-atmospheric corrosion the of the present invention is drawn together in the following table 3 listed, the alloying element of representing with weight percentage ranges separately.It should be understood that all values all are approximations.

Table 3

Element	Scope of embodiments	Preferable range	Most preferred range
				C	0.16 to 0.23	0.17 to 0.22	0.18 to 0.21
Si	0.2 to 1.5	0.3 to 1.2	0.5 to 0.9
				Cr	2.0 to 5.0	2.5 to 4.0	3.0 to 4.0
Cu	0.2 to 2.0	0.5 to 1.5	0.7 to 1.5
				Mo	0.8 to 3.0	1.0 to 2.0	1.3 to 1.7
Ni	7.0 to 12.0	8.0 to 10.5	9.0 to 10.5
				Co	13.0 to 17.0	14.0 to 16.0	14.5 to 15.5
V	0.0 to 2.0	0.0 to 0.5	0.02 to 0.05
				W	0.0 to 2.0	0.1 to 1.5	0.025 to 1.0
N	0.0 to 0.04	0.01 to 0.03	0.01 to 0.025

Balance is common impurity in iron, optional additive and the business level maraging steel basically.For example, can comprise trace elements in the steel of anti-atmospheric corrosion the of the present invention, as the S of maximum 0.01pbwt, the P of 0.01pbwt, and the N of maximum 0.05pbwt at most.

The purpose that adopts Elements C is intensity and the hardenability that increases alloy by thermal treatment.The ladle of anti-atmospheric corrosion the of the present invention is drawn together 0.16 to 0.23pbwt C.But the purpose that adopts Si be make steel in the course of processing, obtain castibility and mobile aspect improvement character.The ladle of anti-atmospheric corrosion the of the present invention is drawn together 0.2 to 1.5pbwt Si.The purpose that adopts Cr is to improve erosion resistance, intensity and the hardenability of these alloys.The ladle of anti-atmospheric corrosion the of the present invention is drawn together 2 to 5pbwt Cr.

Adopting the purpose of element Cu is to provide improved erosion resistance and weathering resistance for the product made from steel of finally finishing.Cu and Cr, Ni and Mo have improved the erosion resistance of alloy together.The ladle of anti-atmospheric corrosion the of the present invention is drawn together 0.2 to 2pbwt Cu.The purpose that adopts elements Mo is to improve the hardenability of HSS.The ladle of anti-atmospheric corrosion the of the present invention is drawn together 0.8 to 3pbwt Mo.The purpose that adopts element Ni is intensity and the toughness that increases alloy.The ladle of anti-atmospheric corrosion the of the present invention is drawn together 7 to 12pbwt Ni.Adopting the purpose of Elements C o is to gain in strength.The ladle of anti-atmospheric corrosion the of the present invention is drawn together 13 to 17wt% Co.

It should be understood that and adopt alloying element V, W and N will choose wantonly.The purpose that adopts element V is to improve hardness, or improves toughness under given firmness level.The ladle of anti-atmospheric corrosion the of the present invention is drawn together the V up to about 2pbwt.The purpose of employing W provides the improvement character of intensity and hardness aspect.The ladle of anti-atmospheric corrosion the of the present invention is drawn together the W that mostly is about 2pbwt most.Adopting the purpose of element N is the stable austenite phase, increases the intensity of alloy simultaneously to a certain extent.The ladle of anti-atmospheric corrosion the of the present invention is drawn together the N up to about 0.04pbwt.

By adopting more benign (benign) element to replace element with high activity, as aluminium and/or the titanium that contains in traditional maraging steel or other superstrength precipitation hardening alloy, therefore the steel of anti-atmospheric corrosion the of the present invention has been endowed stronger weather-resistant.Adopt active lower element on purpose to replace element with high activity, and employing simultaneously is through the C and the Si of the wise certain level of judging, can in air, carry out single fusion and cast thereby generated, but show the alloy of excellent stability and castibility (flowability) simultaneously.

In a kind of embodiment preferred, the steel of anti-atmospheric corrosion the of the present invention is a desirable form by investment cast.Preferably, the steel of anti-the atmospheric corrosion is melted and pours into a mould in single operation, and different is that this operation need not to carry out in inactive environment with traditional maraging steel.It should be understood that the steel of anti-atmospheric corrosion the according to principle of the invention preparation can be easy to be cast as complicated structure in air.

Although it should be understood that preferably to adopt carries out fusion in air, also can adopt the gas of protectiveness.For example, but for improving castibility, can during the fusion liquid state or gasiform argon covered on the surface of charge material (charge material).In addition, begin about ten minutes,, then can obtain body of casting surface preferably if on the cooling housing, remove cooling housing ambient air by placing Cap for tin body at the foundry goods solidified.Yet this is not a limitation of the present invention.

In general, the steel of anti-atmospheric corrosion the of the present invention has the following comprehensive mechanical character of wanting: (i) yield strength is greater than about 230,000psi, be preferably about 255,000 to 300, in the scope of 000psi; (ii) tensile strength is greater than about 250,000psi, be preferably about 255,000 to 320, in the scope of 000psi; And (iii) elongation surpasses approximately 6%, is preferably 10 to 14%.Except these mechanical propertiess, but the steel of anti-atmospheric corrosion the of the present invention also demonstrates the good character of castibility, flowability, weldability and resistance to atmospheric corrosion aspect.

Can design the prescription of the steel of anti-atmospheric corrosion the of the present invention,, thereby adapt to specific steel application scenario with intensity, toughness, elongation and the erosion resistance that is provided at the aspiration level in the above-mentioned scope as required.By optionally adopting alloying constituent and/or, can obtaining the performance of different levels in these scopes by changing the consumption of these alloying constituents.

As mentioned above, the steel of anti-atmospheric corrosion the of the present invention can be melted in air ambient and pour into a mould, can fusion in air, cast and can be cast as in air and be desired results.After cast member was cast, the typical process of processing this steel of anti-the atmospheric corrosion comprised the following steps: (a) high temp/high pressure fixed (consolidation); (b) homogenizing; (c) sosoloid thermal treatment; (d) cooling; And it is (e) aging.

The fixed step of high temp/high pressure preferably adopts the hot-isostatic pressing mode to carry out.During the hot-isostatic pressing step, the investment cast product is positioned in the specified pressure container, this specified pressure container can surpass about 14, under the inert gas pressure of 000psi, with this product by heating to specific temperature.The high temperature and high pressure that is adopted in this technology causes the inherence casting in the product to be interrupted (internal castingdiscontinuities), as hole, gas or shrinkage hole generation avalanche, reduce greatly thereby obtain subsurface defect, and mechanical properties foundry goods preferably.

Cast article is preferably about 15, and the pressure of 000psi and being higher than under the temperature of about 1,900  more preferably at about 1,900  to 2, in the temperature range of 250 , in rare gas element, carries out hot-isostatic pressing in the chamber (chamber) of filling as argon gas.Before being heated, filling or loading argon gas reach a certain specific pressure range in the pressure chamber.Make indoor temperature be elevated to desired temperature, this causes indoor pressure to increase to the level of expectation.Kept the about 3-5 of this desired temperature hour, then with the foundry goods cool to room temperature.After the hot-isostatic pressing product is detected normally, to estimate the encapsulation situations of hole.

The homogenizing treatment step carried out about 1 to 6 hour in about 2,225  temperature ranges in about 2,000  in neutral gas.Homogenizing is handled and to be used to reverse and/or microstructure change that neutralization heat isostatic pressing cycle period produces, and minimizes any chemical separation (segregation).

The sosoloid heating steps carried out about 1 to 4 hour in about 2,100  temperature ranges in about 1,600  in neutral gas, adopted fast gas air blast (rapid gas fan) then and cool to room temperature.The effect of sosoloid heating steps is that microstructure is under the austenite condition, and is martensite by quick cooling with this thaumatropy.

Cooling step be by finish for the time after about 1 to the 4 hour sosoloid thermal treatment 24 hours in, at (preferred-90  are to-100 ) below-50  freezing cast article that is in room temperature approximately, arrive martensitic conversion thereby finish austenite.Aging step was carried out under the temperature range of about 800 to 1,000  about 1 to 6 hour, to obtain the above-mentioned comprehensive mechanical character of expectation.

Following table 4 has been listed according to principle of the present invention, is used to make the steel of anti-the atmospheric corrosion and preferred, the preferred and most preferred processing parameter that adopts.It should be understood that all values all are approximations.

Table 4

Procedure of processing	Preferably	More preferably	Most preferably
				Hot-isostatic pressing	1,900  to 2,250  @ 14,000 to 16,000psi, 3 to 5 hours	2,000  to 2,240  @ 14,000 to 16,000psi, 3 to 5 hours	2,125  to 2,220  @ 14,000 to 16,000psi, 3 to 5 hours
Homogenizing	2,000  to 2,225 , 1 to 6 hour	2,150  to 2,220 , 2 to 5 hours	2,205  to 2,215 , 4 hours ± 15 minutes
				Sosoloid thermal treatment	1,600  to 2,100 , 1 to 4 hour	1,800  to 1,950 , 1 to 3 hour	1,875  to 1,925 , 1 hour ± 15 minutes
Cooling	-350  were to-50 , 1 to 8 hour	-110  were to-75 , 1 to 3.5 hour	-110  were to-90 , 3 hours ± 15 minutes
				Aging	800  are to 1000 , 1 to 6 hour	900  to 1,000 , 3 to 5 hours	925  are to 950 , 4 hours ± 15 minutes

Hands-on approach according to the present invention prepares three exemplary embodiment of the present invention's steel of anti-the atmospheric corrosion.These embodiment are called as RNR-2 cited in the following table 5, RNR-3, RNR-4, RNR-5, RNR-6 and RNR-2L.These embodiment are by combined content alloying constituent as shown in table 5, carry out fusion, cast in air, and the foundry goods that the alloy mixture of combination is cast as expectation is prepared.

Cast member carries out about 3 hours hot-isostatic pressing and handles in the temperature of about 2,125  and about 15 under the pressure of 000psi.2,125  are to about 2, cast member to hot-isostatic pressing in the temperature range of 200  carries out about 4 hours homogenizing processing, then about 1, carry out about 1.5 hours sosoloid thermal treatment under the temperature of 900 , the heat treated cast member of this sosoloid is then by fast gas air blast cool to room temperature, and under the temperature of-100  approximately freezing about 1 to about 3 hours subsequently, thus retained austenite is converted into martensite.This cast member wore out 4 to 6 hours under the temperature of about 950  then, to obtain the mechanical properties of expectation.

So the mechanical properties of the embodiment that forms also is provided in the following table 5:

Table 5

Alloy	RNR2	RNR3	RNR4	RNR5	RNR6	RNR2L
							Element
C	0.18	0.17	0.16	0.16	0.16	0.16
							Mn	0.02	0.01	0.01	0.01	0.01	0.02
Si	0.71	0.58	0.55	0.6	0.62	0.56
							Cr	2.67	2.07	2.06	3.15	2.05	3.20
Ni	10.07	9.91	9.87	9.77	9.98	9.74
							Mo	1.19	0.96	2.28	2.16	0.97	0.94
Cu	1.44	0.64	0.65	0.6	0.64	0.63
							Co	15.85	14.92	14.68	14.42	14.78	14.67
W	0.1	0.01	0.02	0.02	1.11	0.01
							N	0.004	0.004	0.004	0.004	0.004	0.004
V	0.23	0.01	0.01	0.01	0.01	0.01
The mechanical test data
							YS(KSI)	278	251	277	278	260	234
UTS(KSI)	303	279	304	305	292	267
							％EL	10	11	6	9.3	10	7
％RA	36	35	24	30	33	20

The embodiments of the invention steel of anti-the atmospheric corrosion is tested, and the result shows that it has the yield strength and the tensile strength properties that can match in excellence or beauty with the forging superhigh strength stainless steel alloy phase of traditional vacuum fusion.Yet the embodiments of the invention steel of anti-the atmospheric corrosion provides with the fusion in the air and the investment casting form of casting in air.

The data that following table 6 provides the physical/mechanical character of the exemplary steel of anti-atmospheric corrosion for preparing according to the method described above to compare with other conventional steel:

Table 6

Alloy	YS，PSI	UTS， PSI	％El	Density	Intensity: weight	Corrosion class	But castibility grade
								RNR2 mean value	278,000	303000	10	0.287	1058362	4	8
RNR3 mean value	251000	279000	11	0.287	973710	5	8
								RNR5 mean value	278000	305000	9.3	0.287	1064450	5	8
RNR6 mean value	260000	292000	10	0.287	1019080	5	8
								The 17-4 casting	159300	167000	8	0.282	592199	8	8
17-4 forges	178000	192000	12	0.282	680851	8
								Supersteel C	170000	185000	7	0.282	656028	9	5
The Ti-6-4 sheet	140000	150000	10	0.16	937500	10
								Ti-6-4 mean value	122000	134000	7	0.16	837500	10	3
Custom 465	234000	257000	12	0.282	911348	7	2
								13-8PH	210000	225000	12	0.282	797872	8	2
304 stainless steels	30000	70000	35	0.282	248227	9	7
								IC316	35000	75000	35	0.282	265957	10	6
IC8620	120000	140000	10	0.280	500000	1	5

According to aforesaid performance data, the steel of anti-atmospheric corrosion the of the present invention demonstrates yield strength and tensile strength all is better than the character that other is used for the conventional steel of comparison, also has the character that percentage elongation and erosion resistance can compare favourably with other conventional steel that is used for comparison simultaneously.

Therefore, the steel of anti-atmospheric corrosion the provided by the invention can be cast in air, and is particularly designed for overcoming the described shortcoming of above-mentioned traditional ultrahigh-strength steel.Compare with the maraging steel equivalent with their martensite, the resistance to atmospheric corrosion of the steel of anti-atmospheric corrosion the of the present invention is higher, and has the stainless steel better synthesis mechanical properties of forging hardened and precipitation hardening than majority, yield strength surpasses about 230,000psi, tensile strength is greater than about 250,000psi, elongation is greater than 10%, and it then is 35% that area reduces.

But the steel of anti-atmospheric corrosion the of the present invention has excellent flowability and castibility, and this makes them can be used to be cast as complicated thin-wall construction.The activity of the steel of anti-the atmospheric corrosion is lower than other maraging steel, and this makes can carry out fusion and cast in the air, and obtains the comprehensive mechanical character of expectation, and need not to carry out repeatedly vacuum fusion and forge processing.The active less character of this class steel has caused metal-Mo reaction and porousness less.In addition, the steel of anti-atmospheric corrosion the of the present invention directly can be made the shape of approximate net by investment cast.Compare with traditional maraging alloy, the price of these alloys is more cheap, is easier to obtain.Need not to adopt highly purified starting material, these alloys just can reach the mechanical properties of expectation.These alloys are easy to be recovered, thereby have reduced cost, and help environment.Compare with dilute-alloy martensite analogue (4140 or 300M alloy), alloy of the present invention shows better weldability.Compare with traditional ultrahigh-strength steel, they do not need chromium plating or cadmium plating in great majority are used, so they are more friendly to environment.

The steel of anti-atmospheric corrosion the of the present invention can be by the single fusion, thereby has reduced tooling cost significantly.They can be in air in fusion and the air cast become complicated structure, thereby reduced the needed capital outlay of vacuum casting stove.As the alloy of casting in the air, productive rate (output hourly) is apparently higher than the productive rate of the alloy that adopts vacuum fusion.The desired acquisition lead time of the steel of anti-atmospheric corrosion the (acquisition lead-times) reduces, and the production cycle time is faster, and manufacturing cost is lower.Because processing is simpler, whole production time and cycle (preparing and the operating time) are faster, therefore need less stock.Because the steel of anti-atmospheric corrosion the of the present invention just can obtain its character need not to forge under the situation of processing, so the shape and the mechanical properties that do not need progressive die to obtain to expect.Under the situation of cost buying and tooling cost, forge processing and vacuum fusion and can improve their characteristic, to be used for application-specific.

Although open and explained certain embodiments, it should be understood that alloy according to principle manufacturing of the present invention can have the wherein a kind of chemistry of many different chemicals in constituting according to the application-specific of the finished product and constitute.And, it should be understood that temperature described herein, time, pressure etc. all are exemplary, those skilled in the art can design without departing from the spirit of the invention and be different from technological process and chemical property disclosed and explaination.

Claims (10)

1. the superhigh strength steel of atmospheric corrosion resisting of casting in the air, it is by combination C, Si, Cr, Cu, Mo, Ni, Co and Fe and make, wherein, the yield strength of described steel is greater than about 230,000psi, tensile strength is greater than about 250, and 000psi and elongation are greater than about 6%.

2. the superhigh strength steel of atmospheric corrosion resisting of casting in the air as claimed in claim 1 also comprises being selected from V, W, at least a composition of N and its mixture.

3. the superhigh strength steel of atmospheric corrosion resisting of casting in the air as claimed in claim 1, wherein, the content of C is about 0.16 to 0.23wt%, the content of Si is about 0.2 to 1.5wt%, and the content of Cr is about 2 to 5wt%, and the content of Cu is about 0.2 to 2wt%, the content of Mo is about 0.8 to 3wt%, the content of Ni is about 7 to 12wt%, and the content of Co is about 13 to 17wt%, and Fe exists with surplus.

4. superhigh strength steel of atmospheric corrosion resisting, form by following material substantially:

C in about 0.16 to 0.23wt% scope,

Si in about 0.2 to 1.5wt% scope,

Cr in about 2 to 5wt% scopes,

Cu in about 0.2 to 2wt% scope,

Mo in about 0.8 to 3wt% scope,

Ni in about 7 to 12wt% scopes,

Co in about 13 to 17wt% scopes, and

The Fe of surplus.

5. superhigh strength steel of atmospheric corrosion resisting comprises:

C in about 0.16 to 0.23wt% scope,

Si in about 0.2 to 1.5wt% scope,

Cr in about 2 to 5wt% scopes,

Cu in about 0.2 to 2wt% scope,

Mo in about 0.8 to 3wt% scope,

Ni in about 7 to 12wt% scopes,

Co in about 13 to 17wt% scopes,

Mostly be most the V of about 2wt%,

Mostly be most the W of about 2wt%,

Mostly be most the N of about 0.4wt%, and

The Fe of surplus.

6. foundry goods of making by the steel of anti-the atmospheric corrosion, it prepares according to the following step:

In the temperature that is higher than about 1,900  be higher than approximately 14, under the pressure of 000psi, the cast member of being made by the steel of anti-the atmospheric corrosion is carried out about 3 to 5 hours hot-isostatic pressing handle;

Under the temperature more than about 2,000 , described cast member is carried out about 1 to 6 hour homogenizing handle;

In the temperature range of about 2,100 , described cast member is carried out about 1 to 4 hour sosoloid thermal treatment, cool to room temperature then at about 1,600 ;

Be lower than under the temperature of-50  approximately about 1 to 8 hour by the described cast member of refrigated cooling; With

Under the temperature of about 1,000 , described cast member is carried out about 4 to about 5 hours wearing out at about 800 .

7. foundry goods as claimed in claim 6, wherein, before described pressing step, this foundry goods is formed by the following step:

Make up about C of 0.16 to 0.23wt%, about Si of 0.2 to 1.5wt%, about Cr of 2 to 5wt%, about Cu of 0.2 to 2wt%, about Mo of 0.8 to 3wt%, about Ni of 7 to 12wt%, about Co of 13 to 17wt%, and the Fe of surplus;

The composition of the described combination of fusion forms the steel reinforced concrete of anti-atmospheric corrosion compound; And

Pour into a mould the described steel reinforced concrete of anti-atmospheric corrosion compound, form described cast member.

8. make the method for cast member by the steel of anti-the atmospheric corrosion for one kind, comprise the following steps:

Make up about C of 0.16 to 0.23wt%, about Si of 0.2 to 1.5wt%, about Cr of 2 to 5wt%, about Cu of 0.2 to 2wt%, about Mo of 0.8 to 3wt%, about Ni of 7 to 12wt%, about Co of 13 to 17wt%, and the Fe of surplus;

The composition of the described combination of fusion forms the steel reinforced concrete of anti-atmospheric corrosion compound; And

Pour into a mould the described steel reinforced concrete of anti-atmospheric corrosion compound, form described cast member.

9. method as claimed in claim 8 also is included in during the described combination step, adds to be selected from V W, one or more compositions of N and its mixture.

10. method as claimed in claim 8 also comprises the following steps:

In the above temperature of about 1,900  be higher than approximately 14, under the pressure of 000psi, described cast member is carried out about 3 to 5 hours hot-isostatic pressing handle;

Under the temperature more than about 2,000  described cast member being carried out about 1 to 6 hour homogenizing handles;

In the temperature range of about 2,100 , described cast member is carried out about 1 to 4 hour sosoloid thermal treatment, cool to room temperature then at about 1,600 ;

Make described cast member under the temperature that is lower than pact-50  by freezing, cooled off about 1 to 4 hour; With

In the temperature range of about 1,000 , described cast member is carried out about 4 to about 5 hours burin-in process at about 800 .