CN100344786C - High strength heat resistant antiwear vertical mill sheath and its making process - Google Patents

Abstract

The present invention discloses a high-strength heat-resistant antiwear unbreakable vertical mill sheath and manufacture technology thereof, which relates to industries such as mines, building materials, metallurgy, machines, etc. The present invention adopts C, Mn, Cr, Ni and Al as main elements, and is additionally provided with a small amount of Mo and V elements. The rest is Fe low alloy cast steel. After the manufacture technology of the present invention is implemented, the vertical mill sheath has homogeneous fine crystal grain martensite. The present invention has the characteristics of high strength, large rigidity, heat resistance, wear resistance and low manufacture and use cost, for example, when exporting the present invention for ten thousand yuan, an enterprise can obtain the output value as 900 million yuan, and the net profit of the enterprise is 750 million yuan which is equal to 924.78 million yuan. The present invention has wide popularization and application value.

Description

Wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant and manufacturing process

Technical field

The present invention relates to the wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant, be mainly used in industries such as mine, building materials, metallurgy, electric power, machinery.It is grinding, the various ores of refinement or its half-finished various upright turnery machine (also claiming Vertical Mill), as: the key part in the equipment such as raw material mill (raw mill), clinker grinding mill (cement grinding mill), slag mill.The invention still further relates to the manufacturing process of a kind of high strength heat resistant, wear-resisting, crack-free vertical mill sheath.

Technical background

In the existing metallic substance of the China and the world, when the application working temperature was between 280 ℃～300 ℃ for a long time and has strong wear and medium impact, nearly all metallic substance all shows the wretched insufficiency of mechanical property: a part of metal was heat-resisting and not wear-resisting; The a few metals surface is high but poor owing to hardening capacity because of hardness, and inner hardness is little, so the short-term resistance to abrasion can only be arranged; Most metallic substance are not only thermo-labile but also not wear-resisting.Cause for a long time, use the component of machine ubiquity under this operating mode the phenomenon that the life-span is short, replacing is frequent, use cost is high.Cause the basic reason of this phenomenon to be: 280 ℃～300 ℃ these temperature ranges, the temperature band (that is: Ms and Mf) that its beginning at the beginning of many metallic substance martensites changes and ends to change; Undoubtedly, its inevitable temperature range (150 ℃～250 ℃) that also exceed the martensite low-temperaturetempering makes formerly in quenching, and hang down back and the continuous decomposition of high hardness martensitic tissue of obtaining, and its hardness and wear resistance decline to a great extent, and cause the weak point in work-ing life; Same it exceeded also that many metallic substance adopt isothermal quenching (T=210 ℃～300 ℃) or isothermal tempering (240 ℃～300 ℃) and the temperature range of obtaining bainite structure; And cause the former minimizing that obtains bainite quantity, or to change the needle-like lower bainite that obtains be bainite on the featheriness, causes its intensity, hardness to reduce, lack friction durability.

In the world is modern, the mill of the supporting large-scale Vertical Mill of large-scale cement factory and daily output 2500T, 3000T, 4000T grog overlaps (4 in every cover, 5～8 tons of every net weight, external diameter is at 1.9m～2.4m, and interior external diameter all is a sphere, wall thickness 180～260mm, height overall 650～900mm does not wait up and down); Going into to grind wind-warm syndrome is 250 ℃～300 ℃, and mill chamber rotates with Vertical Mill, and mill cover and grinding roller connect firmly, and does the differential rotation in mill chamber, and realization is to the production process of the grinding of mill feed material (grog or slag etc.), pulverizing, homogenizing.Mill cover surface is for material, and what mainly bear is intensive roll extrusion relative wear; It and material, dished wheel and mill chamber perisporium will inevitably produce bigger homogenizing collision impact and grind heat, cause temperature rising in the mill chamber, and increase with rotating speed, strengthen and grind heat.For the mill cover, along circumferentially bearing the huge huge tangential pulling force that produces by the roll extrusion friction again, the at present domestic mill cover that many producers and the development of design studies institutes are arranged, its actual working life less than 4000 hours, price per ton is 2.8 ten thousand yuan～3.2 ten thousand yuan, many mills are enclosed within and occur in the use breaking, and the replacing of being forced to stop production; And import mill cover product to be known as work-ing life be 10000 hours, price per ton is 11～130,000 yuan (Renminbi); And about ten months actual service lives, less than 7200 hours.Seriously influence production and economic benefit and social synthesis's benefit in relevant enterprise.The Chemical Composition of now that the present age is mainly relevant heat-resisting, wear-resistant metal material, quench, that tempering temperature and main Mechanical are converged row is as follows:

(1), wear-resistant cast iron material

Country origin	Classification	The trade mark	Chemical Composition									The degree of rising again of quenching		Main Mechanical under the normal temperature
															c	si	Mn	Cr	Ni	Mo	P	S	Cu	T Quench	T Return	HRC(HV)
			Home products	Wear-resisting GB8263-closes 87 gold medal white cast-iron	kmTBCr 15MO 2-GT	2.8～3.6	≤1.0	0.5～1.0	13～18	0～1.0	0.5～3.0	≤0.10	≤0.06	0～1.2													920℃～1000℃	200℃～300℃	54-56
KmTBCr 9Ni 5Si 2	2.5～3.6	1.5～2.2													0.3～0.8	8～10	4.5～6.5	0～1.0	≤0.15	≤0.1		750℃～825℃	250℃～300℃	52-53
					KmTBCr 20MO 2cu 1	2.0～3.0	≤1.0	0.5～1.0	18～22	0～1.5	1.5～2.5	≤0.1	≤0.06	0.8～1.0											960℃～1020℃	200℃～300℃	53-54
External product	The Lay Gao Zhu ferrochrome of having a rest grinds in the public anti-state of moral department	GCr 9Ni 5Si 2													2.6-3.2	1.8-2	0.4-0.6	7-11	5-6.5	0-0.5									55(600)
			GCr 15MO 2	2.3-3.6	＜0.8	0.5-0.9	14-16	＜1.2	2-3																55(600)
		De Sinai state public mill uncle department casting power high ferro turtledove chromium													GCr 20MO 1	2.3-2.6	＜0.8	0.5-0.9	18-20	＜1.2	1.2-1.4							55(600)

Can draw to draw a conclusion through serious analysis, research and in conjunction with the rig-site utilization practice above-mentioned materials:

1. Zhong Guo KmTBCr ₉Ni ₅Si ₂The Chemical Composition group ratio of NiCr alloy wear-resisting cast iron contained the German Lai Xie GCr of company ₉Ni ₅Si ₂The Chemical Composition of alloy wear-resisting cast iron; This alloy material all contains valuable chromium (Cr) 9%, nickel (Ni) 5%; Through being heated to 750 ℃～825 ℃, behind insulation 4～10h (deciding according to sectional dimension), the air cooling of coming out of the stove is realized quenching its hardness HRC 〉=55; It organizes eutectic carbides [(CrFe) ₇C ₃+ (FeCr) ₃C]+proeutectoid carbide+martensite+residual austenite; Again through be heated to 250 ℃～300 ℃ and be incubated 4～16h after come out of the stove, air cooling is realized temper.To eliminate the quenching internal stress, improve its toughness.After above-mentioned processing, the hardness HRC=55 that claim in on-the-spot test hardness HRC=52～54 and German Lai Xie company on its surface is more or less the same.

2. Zhong Guo KmTBCr ₁₅MO ₂The wear-resisting high-chromium alloy cast-iron Chemical Composition of-GT group is than the GCr that has contained Lai Xie company equally ₁₅MO ₂The element set ratio, through heat 920 ℃～1000 ℃ the insulation 2-6 hour air cooling of coming out of the stove, its surface hardness HRC 〉=58; Metallographic structure is: eutectic carbides (CrFe) ₇C ₃+ proeutectoid carbide+martensite+residual austenite; 200 ℃～300 ℃ of reheat also are incubated 2-8 hour, the air cooling of coming out of the stove, and the medium impact wearing and tearing also can be born in surface hardness HRC 〉=54～56, and it is approaching with the product surface hardness HRC=55 of Lai Xie company.

3. Zhong Guo KmTBCr ₂₀MO ₂Cu ₁Chemical group than the Chemical Composition that has still also contained German this company's high-chromium alloy cast-iron of uncle's power turtledove; Both all contain valuable chromium (Cr) metallic element 20% of a great deal of, expensive molybdenum (Mo) metallic element about 2%; Through heating 960 ℃～1020 ℃ insulations 2-6 hour, the air cooling of coming out of the stove is realized quenching its HRC 〉=58; Metallographic structure is: eutectic carbides (CrFe) ₇C ₃+ proeutectoid carbide+martensite+residual austenite; Through heating 200 ℃～300 ℃ insulations 2-8 hour, the air cooling of coming out of the stove is realized temper, its surface hardness HRC=54～56 again.And can bear the abrasive wear of greater impact, thus the vertical mill sheath surface hardness HRC ≈ 63～65 that this company of relevant uncle turtledove is produced, and can reach 10000 hours saying work-ing life, be theoretically unsound and practical basis.

4. 6 kinds of masters of above-mentioned 3 classes are nickeliferous, chromium, molybdenum antiwear cast iron alloy, wherein remove Cr ₁₅MO ₂Hardening capacity≤the 40mm of class; The hardening capacity that other two class is 4 kinds all 〉=100mm; Its common weak point: hardness is on the low side, the wear resistance deficiency, particularly they are in the hardness of 200 ℃～300 ℃ of martensitic stuctures that temper obtains, being in 280 ℃～300 ℃ strong wear for a long time uses in the operating mode, though its impelling strength slightly increases, but hardness can descend, and work-ing life can be shorter continuously.

5. the manufacturing cost height is existing with KmTBCr ₂₀MO ₂Cu ₁Carry out real cost for example and settle accounts (whole metallic elements, steel scrap, the electricity charge, process cost are carried out by market price, element is got all amounts, hair bad rate 15%, dead head molten steel amount 40%):

The A materials cost:

B annealing takes: 24T * 1.15 * 800/T=22080 unit

C process cost: 24T * 1000 yuan/T=24000 unit

D tempering expense: the 24T * 2500 yuan/T=60000 unit of quenching

Cost accounting: 296080+22080+24000+60000=902160 unit (amount to: 36086.40 yuan/T)

E production marketing valency:

By above-mentioned cost, the home products valency is that [902160 * 1.17+153367.2 * 12.05%] * 1.15=1235109.14 unit (amounts to: 51462.88 yuan/T) (attached: sales tax: national tax 17%, land tax 12.05%, profit 15%)

Ten thousand yuan/the cover of ten thousand yuan/T=(264～312) of F imported product valency: 24T/ cover * (11-13), (2,880,000 yuan of average prices), it is than ten thousand yuan of home products expensive (140.5～188.5)/cover.

G uses economical effectiveness to adjust:

1. now use the mill cover by domestic production, the production cost that its grog per ton is formed by the loss of mill cover in the Vertical Mill operation:

2. the corresponding production cost of external mill cover product grog per ton:

3. if domestic vertical mill sheath adopts KmTBCCr ₂₀MO ₂Cu ₁Make, grog then per ton in the Vertical Mill operation by the production cost that the loss of mill cover constitutes is:

The above results shows: to vertical mill sheath if adopt wear-resisting wipla ironcasting, enterprise's manufacturing cost and use cost height; When using external product, its use cost is higher; So add equipment electricity consumption, labor wage, equipment amortization and loss, then use cost can be higher; So seek new heat-resisting, high-abrasive material is imperative.Through extensively receiving rope, now relevant with working conditions other is heat-resisting, wear-resistant metal material is listed as follows:

(2) relevant all kinds of special steels

Sequence number	Classification	The trade mark	Chemical Composition									The tempering temperature of quenching		Main Mechanical under the normal temperature
																	c	Si	Mn	Cr	Ni	Mo	V	P	S	T quenches	T returns	HRC	Бb N/mm 2	α k J/cm 2
			1	Alloy tool steel	Cr 12MoV	1.45-1.7	≤0.4	≤0.4	11-12.5		0.4-0.6	0.15-0.3	≤0.03	≤0.03	1020℃～ 1040℃	300℃															56～59	(Бbb)3400	11
2	Cr 4W 2MoV	1.12-1.25															0.4-0.7	≤0.4	3.5～4	1.9～2.6 (w)	0.8～1.2	0.8～1.1	≤0.03	≤0.03	960℃～ 980℃	300℃	59～60	(Бbb)2900	30
			1		Bearing steel	G8Cr15	0.75～0.85	0.15～0.35	0.2- 0.4	13-16.5				≤0.027	≤0.02	830℃														300℃	57
2	9Cr18Mo	0.95～1.10		≤0.8													≤0.5	16～18		0.4～0.7		≤0.035	≤0.03	1060℃	300℃	56
			1			Ultrafort Steel	32Si 2Mn 2 -MoV	0.28～0.36	1.45～1.75	1.6～1.9			0.35～0.65	0.2-0.35	≤0.035	≤0.03													920℃	320℃	51-52	1880	58
2	45CrNiMoV	0.42-0.49		0.17～0.37	0.5～0.8												0.8～1.1	1.3～1.8	0.2～0.3	0.1～0.2	≤0.035	≤0.03	860℃	300℃	53-54	2020	47
			1				Heat resisting cast steel	ZG30Cr 20Ni 10 GB8492-87	0.2-0.4	≤2	≤2	18-22	8-12	≤0.5		≤0.04												≤0.04				490
2	ZG40Cr 30Ni 20 GB8492-87	0.2-0.6		≤2	≤2	28-32											18-22	≤0.5		≤0.04	≤0.04				450
			1					Wearable cast steel	ZGMn 13 GB5680-85	0.9～1.5	0.3～1.0	11～14															≤0.07	≤0.05	1060～ 1100℃		≤229 (HB)	637～735	147
2	42SiMn 2 GB5680-85	0.37～0.44		0.6～1.0	1.4-1.8														≤0.04	≤0.04	840～ 880℃	200～ 300℃	49-54		22
			1						Heat resisting iron	RTCr 16 GB9437-88	1.6-2.4	1.5-2.2	≤1	15-18													≤0.1	≤0.05			(HB)400 -450	340
2	RQTAl 22 GB9437-88	1.6-2.2		1-2	≤0.7	20-24 (Al)												≤0.1	≤0.05			(HB)241 -364	300

Through conscientiously searching row, analysis, comparison, research, in last table obviously as seen: chromium, molybdenum class alloy bearing steel, hardening capacity is preferably arranged, intensity and hardness, but they contain the noble metal elemental chromium (Cr) of (15%～18%) in a large number, thereby cause the manufacturing cost and use cost height, because of its under the forging condition, the a little higher than antiwear cast iron alloy of hardness, when it adopts the steel casting of equal composition, its hardness can slightly descend, and can show the deficiency of friction durability and toughness in the applying working condition of cruelty.For Ultrafort Steel, though good hardening capacity, toughness are arranged, but still be that hardness is lower, the application operating mode can not be adapted to.

Chromium, the nickel of Heat resisting cast steel material because of containing a large amount, its outstanding behaviours only are the oxidation-resistance under the high temperature, and the highest use temperature that makes can reach 1100 ℃～1150 ℃, but its intensity is very low, and both are respectively 490N/mm ², 450N/mm ²Undoubtedly, its hardness also can be very low.So they more can not satisfy the application operating mode.Equally, outstanding heat resisting iron RTCr ₁₆The temperature resistance that it shows reaches 900 ℃ unexpectedly, but intensity Б _b=340N/mm ²And the suitable HRC=42 of hardness HB=400-450～47; RQTAl ₂₂Heat resisting iron, its maximum operation (service) temperature can reach 1100 ℃, we can say: it is a kind of resistant to elevated temperatures cheap material, be equivalent to HRC=25～38 but only have only HB=241-364 because of its hardness, and intensity also has only Б _b=300N/mm ²So they can't satisfy the application working condition requirement at all.Wearable cast steel 42SiMn ₂Be the common used material that China tank track is made, through 840 ℃～880 ℃ quenchings, air cooling after being heated to 200 ℃～300 ℃ insulations again, its HRC=49-54, α _k=22J/cm ², on the low side because of its hardness, if adopt the steel casting that keeps its identical Chemical Composition, its hardness can reduce, the requirement of more not satisfied application operating mode.

About the ZGMn in the wear resisting steel ₁₃Series, because the impact of application operating mode and wearing and tearing are not enough so that its surperficial austenite changes into martensite, hardness, intensity, wear resistance that applying working condition is showed down all can be very poor; When the practical application working temperature is 280 ℃～300 ℃, will make its former solution treatment under normal temperature or static state, have carbide to separate out again along crystal boundary in the single austenite structure, cause the hurried rising of fragility, toughness descends.So under this specific application operating mode, ZGMn ₁₃Series Steel can't be used at all.

To the Cr in the tool steel ₁₂MoV is through 1020 ℃～1040 ℃ quenchings, again through 300 ℃ of tempering, and its bending strength Б _BbUp to 3400N/mm ², hardness is mark HRC=59 in Volume Four hot-work of thermal treatment handbook and heat treatment process parameter (being finished in October, 1992 by thermal treatment specialty branch of mechanical engineering society numbering), and obviously indicates HRC ≈ 56 in the tempering process curve; Tool steel Cr ₄W ₂MoV is through 960 ℃ of quenchings, again through in hot-work and heat treatment process parameter form, marking hardness HRC=61 after 300 ℃ of tempering, and in its corresponding tempering process curve, clearly showing same material, same quenching, tempering temperature, two groups of different pieces of information: Б appear unexpectedly _Bb1=2900N/mm ², HRC ₁=59, ak ₁=28J/cm ²Б _Bb2=2380N/mm ², HRC=57～58; Ak=50J/cm ²A lot of etc. picture and text discrepancy like that.Study that Sinomania handles and Metal Material Science, all kinds of handbook, standard are given production practice and the such sensation of scientific and technological researchist hard: all handbook performance datas are mainly due to lacking practicality, so inevitable thereupon tightness, integrity, systematicness, logic, science, the reliability of lacking again.Mainly show: same things, each book viewpoint differs, and in same the handbook differ in front and back; Picture and text are not inconsistent, and a lot of performance datas do not have, and many data or figure are wrong, and standard is coarse, and all handbooks all have dense statistical, traditional, the narrow-mindedness of research range; Very lack applicability, novelty, popularity, comprehensive and guiding.Undoubtedly along with the science and technology and the development of production level, they will progressively lose authority and directiveness, the basic reason that causes this phenomenon is exactly that some expert, scholar are busy with writing books to expound a theory, and rope row are pieced together everywhere, does not have practical significance and has the end to put the research of arrow and do not pay attention to more being reluctant to be engaged in.

In any case, for alloy tool steel, when it adopted the identical steel casting of Chemical Composition, its hardness and toughness can obviously descend, even if keep original forging hardness HRC=56～58 can not be from basic solutions economy, attrition resistant application working condition requirement.

Summary of the invention

The objective of the invention is to be to provide a kind of high heat-resisting, wear-resisting non-cracked vertical mill sheath, it has castibility defectives such as pore-free, flawless, no burning into sand, the heavy burden carrying is changeed steadily, long service life, the characteristics that manufacturing cost and use cost is low satisfy the requirement of modern vertical mill sheath applying working condition fully.

Another object of the present invention provides the manufacturing process of the wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant.

For reaching the above object, the inventor investigates repeatedly, analyzes, tests, studies through reaching 3 years, and is expensive up to more than 150 ten thousand yuan, succeeds finally, and its technical measures are as follows:

The present invention selects for use is to be main added elements with C, Mn, Cr, Ni, Al, auxilliary a small amount of Mo, the V element of adding; The average carbon content of this cast steel is 0.59%, and much smaller than 1%, and average alloy content only is 4.775%, less than 5%; Simultaneously its on average to contain carbon equivalent (Ceq) only be 0.8504167%, so its belongs to medium carbon low alloy steel, so it has good castibility, repair welding, thermal treatment and processibility.

This is avoided just or reduces mill cover blank castibility defective, improves the blank qualification rate, reduces the key problem in technology of manufacturing cost.The vertical mill sheath blank after annealing roughing again through quenching oil cooling and tempered processing, because of its Martensite temperature transition point (Ms ℃) is 320 ℃＞300 ℃, so after implementing manufacturing process provided by the present invention, its microstructure is the even fine and closely woven high hardness martensitic and the austenite of micro residue.It shows high intensity and hardness and has good impelling strength, up to the present, also still finds no the material that is used for making vertical mill sheath than it more suitably both at home and abroad.

The assembly element mass percent of cast steel of the present invention is:

C：0.50～0.68； Si：0.2～0.5； Mn：0.4～0.7； Cr：1.25～1.75；

Ni：0.4～0.9； Mo：0.18～0.32； V：0.08～0.17； Al：1.1～1.7；

P≤0.03； S≤0.03； Fe：93.22～95.89；

Carbon (C), C is intensity, the hardness of decision metallic substance, the principal element of wear resistance, and this is that it has not only determined steel martensitic quantity after quenching because few more than the C content in the steel, form and hardness (are M but also determined martensite to begin to be converted to the temperature band of ending to change _s℃ and M _f℃ zone); It has also just determined after martensite is obtained in quenching the degree of its residual austenite when principle is determined the type of cooling; Undoubtedly, it has also determined to obtain the temperature M of tempered martensite _x℃ and the minimum temperature M that decomposes fully of martensite _T℃.In this sense, determine low-temperaturetempering (150 ℃～250 ℃) in former all teaching materials, the handbook, it obtains and is organized as saying of tempered martensite, no longer is of universal significance.Strictly speaking, the steel part of the martensite that obtains that quenches is heated to the maximum value of the undecomposable temperature of its martensite again, through insulation, comes out of the stove through oil cooling or air cooling again, this process is named the low-temperaturetempering processing, obtain and be organized as tempered martensite+residual austenite; General hardness HRC=55～67.Carbon among the present invention (C) part forms plain sosoloid of iron and and Fe formation cementite (Fe in solid solution in α-Fe ₃C), C also with the unnecessary alloying element of solid solution in ferrite form alloy carbide: VC (V is insoluble in the cementite, directly and C in conjunction with formation VC), Mo ₂C, Mn ₇c ₃, Cr ₇C ₃Simultaneously also and be dissolved in cementite (Fe ₃C) alloying element forms the alloyed cementite of lattice complexity jointly: (FeCr) ₃C, (FeMn) ₃C, (FeMo) ₃C, (CrFe) ₂₃C ₆, (MoFe) ₂₃C ₆Deng; Thereby intensity, hardness and the wear resistance of steel alloy have been improved; Carbon content is to transition temperature Ms ℃ and termination transition temperature M of martensitic initial formation from austenite _f℃ analysis learns, when carbon content from 0.5%～0.7% the time, its Ms ℃ is 280 ℃～250 ℃; M _f℃ greatly after 0 ℃～-55 ℃ quenchings, except that even martensitic stucture, residual austenite≤5%.Martensite hardness HRC=63～67; For crystal grain after making thermal treatment the thinnest: grain fineness number≤20um ², enough intensity, hardness should be arranged, good toughness is arranged again, its carbon content is controlled between 0.50%～0.68% in the present invention.

Silicon (Si), Si often allocates into reductor, and when content≤0.85%, all solid solutions improve intensity, the hardness of ferrite consumingly in ferrite, and its change in toughness is very little; When content＞0.85%, its toughness significantly descends; Si and has the increase fluidity molten steel except that improving temper resistance, improve the effect of castability.So the content of Si is controlled between 0.2%～0.5% among the present invention.

Manganese (Mn) is to be dissolved in ferrite to form alloy ferrite α-Fe (Mn) and form alloy carbide Mn ₇C ₃With alloyed cementite (FeMn) ₃C improves hardening capacity, and the homogenizing tissue improves intensity, hardness and flexible important element; In addition, Mn energy and impurity S form MnS and remove certainly with the slag form, so Mn has the function of purify hot metal and automatic removal of impurities.Simultaneously, Mn also is good reductor, reduces the fragility of steel, improves the quality of steel.Because of Mn content at＜0.9% o'clock, the intensity of steel, hardness are to increase with its content, and that toughness changes in this scope is very little; But when Mn content＞0.9%, its toughness sharply descends.For both reaching strengthening effect, toughness is descended, be controlled between 0.4%～0.7% so contain the Mn amount among the present invention.

Chromium (Cr), their parts of molybdenum (Mo) are dissolved in ferrite, form alloy ferrite α-Fe (Cr), α-Fe (Mo); Another part forms particulate, dispersive stable alloy carbide: Cr ₇C ₃, Mo ₂C; Some is dissolved in cementite (Fe ₃C) in, equally with trickle, disperse, fill the air the stable alloy cementite: (FeCr) ₃C, (FeMo) ₃C, (CrFe) ₂₃C ₆Be present in the crystal boundary of high temperature austenite and between crystal boundary Deng state, except that the obstruction austenite crystal is grown up, and be to obtain even fine-grained martensitic tissue after quenching and the tempering to have laid a good foundation, thereby improve its intensity, hardness and wear resistance and high-temperature oxidation resistance significantly; Cr, Mo also have the effect that C curve is moved to right and significantly improve hardening capacity simultaneously.The Cr constituent content was at≤1% o'clock, its intensity, hardness and impelling strength are to increase with the increase that contains Cr, but when content 1% (during Cr≤2%, the notched bar impact strength of steel slightly descends, when Cr content＞2%, intensity and impelling strength obviously descend, for both reaching strengthening effect, the little purpose and toughness descends is so Cr content is controlled between 1.25%～1.75% among the present invention; And Mo contains≤7% o'clock, the intensity of steel and hardness increase with the increase that contains the Mo amount, but the toughness of steel can be with the increase that contains the Mo amount by 245J/cm ²Sharply drop to 68.6J/cm ², particularly when containing Mo amount＞0.4% in the steel, its toughness descends remarkable especially; Allocating into of Mo can be improved temper resistance in addition, avoids temper brittleness.So the content of Mo should be controlled between 0.18%～0.32%.

Nickel (Ni) is to be dissolved in ferrite to form the important element that alloy ferrite α-Fe (Ni) realizes solution strengthening; When containing Ni＜3%, the intensity of its steel, hardness, toughness all increase with the increase of ni content.When its content surpasses 3%, the toughness of steel has downtrending, should reach strengthening effect, plans as a whole organic assembly of each element again, also will consider cost simultaneously, so ni content is controlled in 0.4%～0.9% scope among the present invention.

Vanadium (V), V and C form disperse, the vanadium carbide (VC) and (V of tiny and extreme hardness (HRC=71-75) ₂C), it is present in the crystal boundary of high temperature austenite and between crystal boundary, hampers growing up of crystal grain consumingly; When V content is 0.04%～0.1%, and temperature is 912 ℃～960 ℃, and its austenite crystal changes very little, and therefore, V allocates quench martensite grain structure after back martensite and the 300 ℃ of tempering of refinement significantly into.Undoubtedly, it has greatly improved intensity, hardness and the wear resistance of steel.Organic assembly of double other each alloying element of event among the present invention, the content of V is defined as 0.08%～0.17%.

Aluminium (Al), Al are the intensive oxygenants, and its saturation solubility in ferrite is up to 36%; It has the intensive desoxydatoin in molten steel, and tangible high-temperature oxidation resistant effect is arranged, and can significantly improve M simultaneously _S℃ effect, also just synchronously improve M naturally _f℃ the point.

Thereby use the back low-temperaturetempering gained martensitic stucture of quenching at 280 ℃＜T ₂≤ 300 ℃ still keep the hard martensitic stucture of former height and wear resisting property and hot strength.

According to the needs of martensite formation temperature, so Al content is 1.1%～1.7% in the invention.

Phosphorus (P), P descend steel plasticity and toughness at normal temperatures, and have in the crystallisation process of steel and promote C, Mn to produce the tendency of segregation, thus among the present invention P content be defined as≤0.03%.

Sulphur (S), S exists with the form of FeS and MnS in steel.MnS enters slag, but FeS and Fe can generate low-melting eutectic, is distributed on the crystal boundary, has weakened the crystal boundary bonding force, and steel, is very easily broken when stressed hot, thus in the invention content of S be controlled at≤0.03% scope in.

Among the present invention because S, P impurity level are few, the choosing amount of joining of Si, Mn, Mo, V is that its toughness is descended, can improve in the scope of its intensity, hardness again, (monolateral through hardening layer depth hx 〉=60mm) has also improved its toughness when improving intensity, hardness greatly and the amount of allocating into of Cr, Ni has not only improved its hardening capacity; Particularly multiple alloy carbide and alloyed cementite: VC, Mo ₂C, Mn ₃C, (FeCr) ₃C, (FeMn) ₃C, (FeMo) ₃Deng with trickle, even, fill the air shape and be distributed in the crystal boundary or between crystal boundary, when improving its intensity, hardness, wear resistance, improved its high temperature resistant property significantly, an amount of adding of Al has improved M effectively _s℃ and Mf ℃ transition point (M _S℃=320 ℃, M _f12 ℃ of ℃ ≈), except that significantly having reduced the content of residual austenite in martensite, also improved the needed temperature of martensitic decomposition greatly, thus it 280 ℃～still keeping high intensity, hardness, wear resistance and toughness below 300 ℃.

A kind of high strength heat resistant of the present invention, its used cast steel of wear-resisting, shock-resistant, non-cracked vertical mill sheath, adopting electric furnace to join stove by Chemical Composition smelts, can adopt Al for carrying out final deoxidation treatment, tapping temperature is 1500 ℃～1520 ℃, treat that spectroscopic analysis confirms that its Chemical Composition meets the requirements, can cast when molten steel temperature is 1470 ℃～1490 ℃.Its concrete production technique is as follows:

1, the casting of blank: going out temperature is 1500 ℃～1520 ℃, and pouring temperature is 1470 ℃～1490 ℃, and foundry goods should be unpacked at 250 ℃～270 ℃, carries out sand removal and the work of cutting rising head after unpacking immediately, and cutting dead head casting temperature should be 200 ℃～250 ℃.

2, to the processing of casting defect: the local casting flaw of cast(ing) surface visibility after being with 200 ℃～250 ℃ polishings of temperature and removing, is adopted the repair welding of A302 welding rod, and weld seam should be continuous, smooth, and welding slag should be removed totally; Postwelding adopts high speed grinding wheel polishing totally or again to advance stove integral body in the lump to overlap, burr, crator and spatter and is preheated to 250 ℃～280 ℃ and carries out above-mentioned mill, benefit work.

3, anneal: the blank integral body after will leveling is advanced stove and is heated to 840 ℃～860 ℃ and be incubated 6～8 hours furnace cooling.

4, mechanical workout:

(1) essence is cast the inside and outside spherical surface of shape, go the scar knurl mill, polishing;

(2) line: with blank hang on platform by work center line perpendicular to the platform centering and be coated with white powder, be during benchmark is looked for, to press the seam internal diameter again with the external diameter, the inclined-plane, the monolateral 2mm～2.5mm that all stays of both ends of the surface rules.

(3) rough turn: the blank that will rule mill cover hangs on big vertical lathe, press the line centering and clamps 1900 ° of rough turn upper surface, back, seam internal diameter, cooperation inclined-plane and ball external diameter Φ _-6Turn-over is the basal plane smoothing with face work, with 1900 ° of external diameter φ _-6In looking for, rough turn again other end, seam internal diameter and interior inclined-plane.

(4) to the processing of foundry goods cast inside defective: the work in-process after rough turn are carried out hundred-percent super spy, to the latent defect found and visibility defective dig clearly clean after, use welding gun flame partial preheating to 200 ℃～250 ℃, adopt the A302 welding rod to carry out repair welding, welding slag must be removed totally, and weld seam should be continuous, smooth.

(5) Q-tempering is handled: will surpass and visit qualified work in-process vertical mill sheath integral body and advance stove and be heated to 850 ℃～860 ℃, and be incubated 5～7 hours oil coolings, and reheat to 300 ℃ again, and be incubated oil cooling after 3-5 hour.

(6) finish turning: the work in-process mill cover that thermal treatment is qualified hangs on big vertical lathe, after smoothing, processes upper surface, seam, interior inclined-plane in looking for external diameter; Turn-over is a basal plane with the end face of processing again, use to look for quadrat method, finish turning other end, seam and in the inclined-plane be shaped.

The mill cover of manufacturing has reached technology, the economical effectiveness of making us unprecedented satisfaction as stated above; All visitors all think: be to make by forging, and the bright and clean as mill of spherical outside surface, hardness test HRC=62～67.Now concrete technology, the economic data (containing mean value) with wear-resisting non-cracked vertical mill sheath of a kind of in one's power high strength heat resistant of the present invention and existing both at home and abroad top mill cover is listed as follows:

The mill cover	Mechanical property		Manufacturing accuracy		Duration of service	Mill cover tax included price	Every cover mill cross rate	The grog cost
									Б b	HRC
	Title	N/mm 2									Measured result	Face runout (mm)	Different moderates (mm)	Hour	Ten thousand yuan/ton	Ten thousand yuan (24T)	Unit/T
The present invention grinds cover			≥2500	62-67	≤0.04	≤0.3	≥8000	2.52	60.48	0.474
	Domestic existing top mill cover										52-54	0.2-0.3	2-3	3000-4000	3.0	72	1.255
Import mill cover				54-56			6000-7500	12	288	2.5098

The present invention compares with prior art, has following remarkable advantage and tangible techno-economic effect:

1. castibility defectives such as pore-free, crackle, burning into sand, the crystalline phase homogeneous microstructure is stable, eliminated because of the castibility defect repair welding and the unrelieved stress due to processing, make the manufacturing accuracy of high level obtain property of a specified duration preservation, thereby avoided under heavily loaded rotary impact and intensive thermal conduction, thermal radiation, the mill cover is converged the disruptive phenomenon of wearing and tearing because of being subjected to inside and outside deformation stress;

2. the significantly raising of intensity, toughness, wear resistance and manufacturing accuracy, except that having improved mill cover work-ing life and Vertical Mill delivery stationarity significantly, the more important thing is and be to improve rotating speed, thereby improved mill hourly output and significantly improve and use the quality product and the economic benefit of enterprise in one's power;

3. long service life, be 2 times of existing domestic mill cover product, and price only is 84% of a domestic product bottom price of the same name, be 21% of world developed country product valency, thereby reduced widely in one's power that the user changes, use the cost of mill cover and changed the labour cost that the stopping production that causes is lost and removed stage makeup and costume because of frequent; Undoubtedly, it improves social synthesis's economic benefit widely.

The whole nation reaches industry mutually to be had at least more than 2000 families, but only 500 families are calculated.By average 4 Vertical Mills of every family, 4 mill covers of every grinding machine, 6 tons of every average net weight, overlapping maximum service life by existing domestic mill is 166 days (about 4000 hours), and mill per ton is set to 30000 yuan of calculating of the price at factory (contain lifting, tie up, deliver goods and 17% national tax, land tax), and so, the annual whole nation need be changed mill cover net weight and be: 96000 tons, blank is heavily about: 115200 tons, mill cover purchase commodity is: 28.8 hundred million yuan; Mill cover is ordered goods, completion acceptance come and go for twice trip expenses be 2,000,000 yuan (it is 2 people that every factory singly takes advantage of at every turn, everyone singly take advantage of at every turn 1000 yuan of lump lump sums of limit with); Still the remuneration and relevant stopping production financial loss that do not comprise annual secondary stopping production replacing vertical mill sheath.

If use the wear-resisting non-cracked vertical mill sheath of a kind of in one's power high strength heat resistant of the present invention, in 166 days, also only need so to change once, its cast steel consumption is existing half of overlapping of grinding, and the mill amount of illegally buying up expense can be with social 16.704 hundred million yuan of the moneys that save, and respective differences is taken 1,000,000 yuan of joint moneys.Since the wear-resisting non-cracked vertical mill sheath of a kind of in one's power high strength heat resistant of the present invention include with the outward appearance workmanship on be better than Japan, Germany, Denmark's product, as arrive the Renminbi price of China by its import: 120,000 yuan/ton, even preferential again 25%, and under the condition of dollar currency rate constant (1: 8.11), 10000 tons of every outlets, then the mill cover is manufactured enterprise and can be created 900,000,000 yuan of the output values, for country earns foreign exchange: 1.10974106 hundred million dollars; If country gives to refund full preferential policy, remove sea, ocean expense far away, then enterprise can have a net gain every year: 7.5 hundred million yuans, amount to: 9247.842 ten thousand dollars.

Quality is good, cost is low so the wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant involved in the present invention has, the characteristics of less investment, instant effect, and it can be in a short time obtains very remarkable economic efficiency for enterprise and country.Therefore, it has extensively use value, promotional value and fruitful economic worth energetically.

Embodiment

The present invention now wear-resisting non-cracked vertical mill sheath of a kind of in one's power high strength heat resistant of the present invention and manufacturing process are provided three examples for further explaining, concrete implementing process is as follows:

1, by the present invention in one's power Chemical Composition join the stove melting, treat that temperature in the time of 1510 ℃, detects its Chemical Composition, cast at 1480 ℃ after removing slag; When foundry goods is cooled to 260 ℃ of unpacking sand removals; Sand removal cutting dead head temperature is 230 ℃.

2, to the processing of casting defect: find in last top dressing dead head cut place through 4 large-scale vertical mill sheaths of scrutiny foundry goods: have only 3 spileholes; Other has shallow-layer burning into sand 2 places, and after adopting the high speed grinding wheel polishing clean, band temperature (220 ℃) is carried out repair welding, and welding rod is A302; Weld seam is continuous, smooth.

3, anneal: the blank integral body after will leveling enters large-scale desk-top electric furnace and is heated to 860 ℃ and be incubated 7 hours furnace cooling.

4, mechanical workout:

1. the smart inside and outside spherical surface of casting shape of polishing, and polishing.

2. line: with blank hang on platform by work center line perpendicular to the platform centering and be coated with white powder, in looking for, press the seam internal diameter with external diameter again, the inclined-plane, both ends of the surface all stay 2mm to rule.

3. rough turn: the blank that will rule mill cover hangs on big vertical lathe, press the line centering and clamps 1900 ° of rough turn upper surface, back, seam internal diameter, cooperation inclined-plane and ball external diameter Φ _-6Turn-over, rough turn other end, seam internal diameter and interior inclined-plane.

4. to the processing of foundry goods cast inside defective: work in-process after rough turn 100% are surpassed spy, only find that end region has (long 52mm of stealthy crackle, dark 3-8mm), after digging totally clearly, use the welding gun fire and fall into partial preheating to 230 ℃, adopt the A302 welding rod to carry out repair welding, welding slag has been removed totally, continuous, the average whole and polishing of weld seam.

5. Q-tempering is handled: will surpass and visit qualified work in-process mill cover integral body and advance stove and be heated to 860 ℃, and oil cooling after being incubated 6 hours.Again it is reheated to 300 ℃, and be incubated 4 hours oil coolings.

6. finish turning: the work in-process mill cover that thermal treatment is qualified hangs on φ 2.5m vertical lathe, with ball external diameter (1900 ° of φ _-6) clamp finish turning upper surface, back, seam, interior inclined-plane in looking for; Turn-over is with 1900 ° of outer ball diameter φ again _-6Face school circle centering is a basal plane with the end face that processes, the processing other end, and seam internal diameter and interior inclined-plane are shaped.

More than be the concrete steps of example 1, example 2,3 is identical.Three examples are concrete

Chemical Composition and mechanical property, purposes and the effect list are as follows:

Embodiment number	Chemical Composition											Mechanical property		Two-sided purposes and effect
															C	Si	Mn	Cr	Mo	Ni	V	Al	P	S	Fe	Б b	HRC
	%	%	%	%	%	%	%	%	%	%	%	N/ mm 2
															1	0.53	0.28	0.58	1.55	0.27	0.84	0.082	1.27	0.024	0.018	94.55 6	2692	62	4 in φ 1.9 * 0.65m mill cover, in April, 2002 to 2003, year operation in February was good.
2	0.67	0.49	0.51	1.67	0.18	0.58	0.13	1.53	0.019	0.021	94.20	2910	67	1 in φ 1.9 * 0.65m mill cover, come into operation and do not find fault year June in May, 2003 to 2004.
															3	0.62	0.38	0.46	1.35	0.23	0.52	0.15	1.42	0.03	0.023	94.817	2780	64	1 in φ 1.9 * 0.65m mill cover, not maintenance in coming into operation year July in August, 2004 to 2005.

Claims (2)

1, the wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant, its assembly element wt per-cent is:

C：0.5～0.68；Si：0.2～0.5；Mn：0.4～0.7；Cr：1.25～1.75；

Ni：0.4～0.9；Mo：0.18～0.32；V：0.08～0.17；Al：1.1～1.7；

P≤0.03；S≤0.03；Fe：93.22～95.89。

2, a kind of manufacturing process that is used to realize the wear-resisting non-cracked vertical mill sheath of the described high strength heat resistant of claim 1, it comprises the following steps:

(1) casting of blank: tapping temperature is 1500 ℃～1520 ℃, and pouring temperature is 1470 ℃～1490 ℃, and foundry goods should be unpacked at 260 ℃～280 ℃, carries out sand removal and the work of cutting rising head after unpacking, and cutting dead head casting temperature should be 200 ℃～250 ℃;

(2) to the processing of casting defect: the local casting flaw of cast(ing) surface visibility after being with 200 ℃～250 ℃ polishings of temperature and removing, is adopted the repair welding of A302 welding rod, and weld seam should be continuous, smooth, and welding slag should be removed totally; Postwelding adopts high speed grinding wheel polishing totally or again to advance stove integral body in the lump to overlap, burr, crator and spatter and is preheated to 250 ℃～280 ℃ and carries out above-mentioned mill, benefit work;

(3) anneal: the blank integral body after will leveling is advanced stove and is heated to 840 ℃～860 ℃ and be incubated 6～8 hours furnace cooling;

(4) mechanical workout:

1. the inside and outside spherical surface that essence is cast shape goes the polishing of scar knurl, holds light;

2. line: with blank hang on platform by work center line perpendicular to the platform centering and be coated with white powder, be during benchmark is looked for the external diameter, rule by seam internal diameter, inclined-plane, both ends of the surface, the monolateral 2mm～2.5mm that all stays again;

3. rough turn: the blank that will rule mill cover hangs on big vertical lathe, press the line centering clamp rough turn upper surface, back, seam and cooperation inclined-plane with external diameter band cutter car to 1900 ° of φ _-6The turn-over centering, rough turn other end, seam, interior inclined-plane;

4. to the processing of foundry goods cast inside defective: the work in-process after rough turn are carried out 100% surpassing spy, to inherent defective and visibility defective dig clearly clean after, use the welding gun fire and fall into partial preheating to 200 ℃～250 ℃, adopt the A302 welding rod to carry out repair welding, welding slag must be removed totally, and weld seam should be continuous, smooth;

5. quench, tempering: will surpass and visit qualified work in-process mill cover integral body and advance stove and be heated to 850 ℃～860 ℃, and oil cooling after being incubated 5～7 hours; Again it is reheated to 300 ℃, and be incubated 3～5 hours oil coolings or air cooling;

6. finish turning: the work in-process mill cover that thermal treatment is qualified hangs on big vertical lathe, in looking for external diameter through smoothing, processing upper surface, seam, interior inclined-plane; Turn-over again is a basal plane with the end face of processing, use to look for quadrat method, finish turning other end, seam, and in the inclined-plane be shaped.