CN1740367A - High strength heat resistant antiwear vertical mill sheath and its making process - Google Patents

Abstract

The present invention is high strength heat resistant antiwear vertical mill sheath and its making process, and the present invention is used in mine, building, metallurgy, machine building and other industry. The high strength heat resistant antiwear vertical mill sheath is made with low alloy cast steel comprising C, Mn, Cr, Ni and Al as main alloy elements, small amount of Mo and V elements, except Fe. The low alloy cast steel prepared through the technological process of the present invention has homogeneous fine crystal grain martensite structure, and has the features of high strength, high hardness, high heat resistance, high wear resistance, high impact strength and low cost.

Description

The 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 the industries such as mine, building materials, metallurgy, electric power, machinery. It is grinding, the various ores of refinement or its half-finished various vertical turnery machine (also claiming Vertical Mill), as: the critical component in the equipment such as raw material grinding 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 metal material of China and the world, be during between 280 ℃～300 ℃ and with strong wear and medium impact for a long time when using working temperature, nearly all metal material all shows the wretched insufficiency of mechanical performance: a part of metal is heat-resisting and not wear-resisting; The a few metals surface is high but poor owing to quenching degree because of hardness, and inner hardness is little, so the short-term wear resistence can only be arranged; Most metal materials 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, its begin at the beginning of many metal material martensites temperature band (that is: Ms and Mf) of changing and ending to change; Undoubtedly, its inevitable temperature range (150 ℃～250 ℃) that also exceed the martensite lonneal makes formerly in quenching, and hang down back and the continuous decomposition of high hardness martensitic tissue of obtaining, and its hardness and wearability decline to a great extent, and cause the weak point in service life; Same it exceeded also that many metal materials adopt isothermal hardening (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, lower hardness, lack friction durability.

In the world is modern, grinding set (4 in every cover of the supporting large-scale Vertical Mill of large-scale cement factory and daily output 2500T, 3000T, 4000T grog, 5～8 tons of every net weight, external diameter is at 1.9m～2.4m, internal-and external diameter all is sphere, wall thickness 180～260mm, height overall 650～900mm does not wait up and down); Entering to grind wind-warm syndrome is 250 ℃～300 ℃, and mill chamber rotates with Vertical Mill, and grinding set and grinding roller connect firmly, and do differential speed rotation in mill chamber, realizes grinding, the pulverizing to mill feed material (grog or slag etc.), the production process of homogenizing. The grinding set surface is for material, and what mainly bear is strong roll extrusion relative wear; It and material, dished wheel and mill chamber perisporium will inevitably produce larger homogenizing collision impact and grind heat, cause temperature rising in the mill chamber, and increase with rotating speed, strengthen and grind heat. For grinding set, along circumferentially bearing again the huge huge tangential pulling force that is produced by the roll extrusion friction, the at present domestic grinding set 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, breaking in use appears in many grinding sets, and the replacing of being forced to stop production; Be 10000 hours and import grinding set product is known as service life, price per ton is 11～130,000 yuan (RMB); And about ten months actual lives, less than 7200 hours. Seriously affect production and economic benefit and social synthesis's benefit in relevant enterprise. Now with the main chemical analysis of relevant heat-resisting, wear-resistant metal material in the present age, quench, that temperature and main Mechanical are converged row is as follows:

(1), wear-resistant cast iron material

Country origin	Classification	The trade mark	Chemical analysis									The degree of rising again of quenching		Main Mechanical under the normal temperature
															c	si	Mn	Cr	Ni	Mo	P	S	Cu	T quenches	T returns	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 field practice to above-mentioned material:

1. China KmTBCr₉Ni ₅Si ₂The chemical analysis group ratio of NiCr alloy wear-resisting cast iron contained the German Lai Xie GCr of company₉Ni ₅Si ₂The chemical analysis 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 carbide [(CrFe)₇C ₃+(Fe·Cr) ₃C]+proeutectoid carbide+martensite+retained 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. China KmTBCr₁₅MO ₂The wear-resisting high-chromium alloy cast-iron chemical analysis of-GT group is than the GCr that has contained equally Lai Xie company₁₅MO ₂The element set ratio, through heat 920 ℃～1000 ℃ the insulation 2-6 hour air cooling of coming out of the stove, its case hardness HRC 〉=58; Metallographic structure is: eutectic carbide (CrFe)₇C ₃+ proeutectoid carbide+martensite+retained austenite; Heat again 200 ℃～300 ℃ and be incubated 2-8 hour, the air cooling of coming out of the stove, the medium impact wearing and tearing also can be born in case hardness HRC 〉=54～56, and it and the product surface hardness HRC=55 of Lai Xie company approach.

3. China KmTBCr₂₀MO ₂Cu ₁Chemical group than the chemical analysis 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 carbide (CrFe)₇C ₃+ proeutectoid carbide+martensite+retained austenite; Through heating 200 ℃～300 ℃ insulations 2-8 hour, the air cooling of coming out of the stove is realized temper, its case hardness HRC=54～56 again. And can bear the abrasive wear of greater impact, thus the vertical mill sheath case hardness HRC ≈ 63～65 that this company of relevant uncle turtledove produces, and can reach 10000 hours saying service life, be theoretically unsound and practical basis.

4. nickeliferous, the chromium of 6 kinds of masters of above-mentioned 3 classes, molybdenum antiwear cast iron alloy are wherein except Cr₁₅MO ₂Quenching degree≤the 40mm of class; The quenching degree that other two class is 4 kinds all 〉=100mm; Its common weak point: lower hardness, wearability is not enough, particularly they are in the hardness of 200 ℃～300 ℃ of martensitic structures that temper obtains, being in for a long time 280 ℃～300 ℃ strong wear uses in the operating mode, though its impact flexibility slightly increases, but hardness can descend, and service life can be shorter continuously.

5. manufacturing cost is high, and is existing with KmTBCr₂₀MO ₂Cu ₁Carry out actual cost for example and settle accounts (whole metallic elements, steel scrap, the electricity charge, processing charges are carried out by market price, element is got all amounts, hair bad rate 15%, dead head molten steel amount 40%):

The A fee of material:* 10 * 390 (Mo)] * 6T/ spare * (1+15%+40%) * 4/cover=[2400+4000 (Cr)+2000 (Ni)+13000 (Mo)] * 1.55 * 6T/ spare * 4 /=33170 yuan/T of cover * 24T=796080 unit

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

C processing charges: 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 amounted to: 51462.88 yuan/T) (attached: sale tax: national tax 17%, land tax 12.05%, profit 15%) for [902160 * 1.17+153367.2 * 12.05%] * 1.15=1235109.14 unit

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 economic effect to adjust:

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

2. the external corresponding production cost of grinding set product grog per ton:

If 3. domestic vertical mill sheath adopts KmTBCCr₂₀MO ₂Cu ₁Make, then the production cost that is made of the grinding set loss in the Vertical Mill operation of grog per ton is:

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

(2) relevant all kinds of special steels

Sequence number	Classification	The trade mark	Chemical analysis									The 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					Abrasion resistant 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 cast 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 upper table obviously as seen: chromium, molybdenum class alloy bearing steel, preferably quenching degree is arranged, intensity and hardness, but they contain the in a large number precious metal elemental chromium (Cr) of (15%～18%), thereby cause manufacturing cost and use cost high, 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 quenching degree, 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 containing a large amount, its outstanding behaviours only are the non-oxidizability under the high temperature, and the highest serviceability temperature that makes can reach 1100 ℃～1150 ℃, but its intensity is very low, and both are respectively 490N/mm²、450N/mm ² Undoubtedly, its hardness also can be very low. So they more can not satisfy the application operating mode. Equally, outstanding heat-resisting cast iron RTCr₁₆The 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; RQTAl₂₂Heat-resisting cast iron, its maximum operation (service) temperature can reach 1100 ℃, can say: it is a kind of resistant to elevated temperatures cheap material, be equivalent to HRC=25～38 but only only have HB=241-364 because of its hardness, and intensity also only has Б_b＝300 N/mm ²So they can't satisfy the application working condition requirement at all. Abrasion resistant cast steel 42SiMn₂The 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, because of its lower hardness, if adopt the steel-casting that keeps its identical chemical analysis, its hardness can reduce, the requirement of more not satisfied application operating mode.

About the ZGMn in the abrasion-resistant stee₁₃Series is because it is not enough so that its surperficial austenite changes into martensite to use impact and the wearing and tearing of operating mode, so the hardness that shows under the applying working condition, intensity, wearability 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, along crystal boundary Carbide Precipitation be arranged again in the single austenite structure, cause the hurried rising of fragility, toughness descends. So under this specific application operating mode, ZGMn₁₃Series Steel can't be used at all.

To the Cr in the tool steel₁₂MoV is through 1020 ℃～1040 ℃ quenchings, again through 300 ℃ of tempering, and its bending strength Б_bbUp to 3400N/mm², hardness is mark HRC=59 in the Volume Four hot-working of heat treatment handbook and heat treatment process parameter (being finished in October, 1992 by heat treatment specialty branch of mechanical engineering society numbering), and obviously indicates HRC ≈ 56 in the tempering process curve; Tool steel Cr₄W ₂MoV is through 960 ℃ of quenchings, again through in hot-working 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, temperature, two groups of different pieces of information: Б appear unexpectedly_bb1＝2900N/mm ²，HRC ₁＝59，ak ₁＝28J/cm ²；Б _bb2＝2380N/mm ²，HRC＝57～58； ak＝50J/cm ²A lot of etc. picture and text discrepancy like that. Study Sinomania hard and process and Metal Material Science, all kinds of handbook, standard to production practices and the such sensation of scientific and technological researcher: all handbook performance datas are mainly due to lacking practicality, so inevitable tightness, integrality, systematicness, logic, science, the reliability of lacking again thereupon. Be mainly manifested in: same thing, 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 are all with dense statistical, traditional, the narrow-mindedness of research range; Extremely lack application, novelty, popularity, comprehensive and guiding. Undoubtedly along with science and technology and the development of the level of production, 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, alloy tool steel, when it adopted the identical steel-casting of chemical analysis, its hardness and toughness can obviously descend, even if keep original forging hardness HRC=56～58 to solve economic, wear-resisting application working condition requirement from basic.

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 pore-free, flawless, without castability defectives such as burnings into sand, it is steady that the heavy burden carrying turns, 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, costs up to more than 150 ten thousand yuan, finally succeeds, and its technical measures are as follows:

What the present invention selected is take C, Mn, Cr, Ni, Al as main added elements, additional a small amount of Mo, V element; 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 castability, repair welding, heat treatment and processability.

This is avoided just or reduces grinding set rough-cast 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 its Martensite temperature transition point (Ms ℃) is 320 ℃＞300 ℃, so after implementing manufacturing process provided by the present invention, its microscopic structure is even fine and closely woven high hardness martensitic and the austenite of micro residue. It shows high intensity and hardness and has good impact flexibility, up to the present, also still finds no the material that is used for more suitably making vertical mill sheath than it 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 the host element of the intensity that determines metal material, hardness, wearability, 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, but also determined that it (is M that martensite begins 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 retained 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 lonneal (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 again the maximum of the undecomposable temperature of its martensite, through insulation, comes out of the stove through oil cooling or air cooling again, this process is named the lonneal processing, obtain and be organized as tempered martensite+retained austenite; General hardness HRC=55～67. Carbon among the present invention (C) part forms iron element solid solution and and Fe formation cementite (Fe in solid solution in α-Fe₃C)， _CAlso 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), Mo₂C、Mn ₇c ₃、Cr ₇C ₃ Simultaneously also and be dissolved in cementite (Fe₃C) alloying element forms the alloyed cementite of lattice complexity jointly: (FeCr)₃C、(Fe·Mn) ₃C、(Fe·Mo) ₃C、 (Cr·Fe) ₂₃C ₆、(Mo·Fe) ₂₃C ₆Deng; Thereby intensity, hardness and the wearability of steel alloy have been improved; Phosphorus content is to transition temperature Ms ℃ and termination transition temperature M of martensitic initial formation from austenite_f℃ analysis learns, when phosphorus content from 0.5%～0.7% the time, its Ms ℃ is 28 0 ℃～250 ℃; M_f℃ greatly after 0 ℃～-55 ℃ quenchings, except even martensitic structure, retained austenite≤5%. Martensite hardness HRC=63～67; For crystal grain after making heat treatment the thinnest: grain size≤20um², enough intensity, hardness should be arranged, good toughness is arranged again, its phosphorus content is controlled between 0.50%～0.68% in the present invention.

Silicon (Si), Si often allocates into deoxidier, 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 improving temper resistance, improve the effect of casting character. 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 Mn₇C ₃With alloyed cementite (FeMn)₃C improves quenching degree, homogenizing tissue, the important element of raising intensity, hardness and toughness; In addition, Mn energy and impurity S form MnS and certainly remove with the slag form, so Mn has the function of purify hot metal and automatic impurity removing. Simultaneously, Mn also is good deoxidier, reduces the fragility of steel, improves the quality of steel. Because of Mn content＜0.9% the time, 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 the stable alloy carbide of particulate, dispersion: Cr₇C ₃、Mo ₂C; Some is dissolved in cementite (Fe₃C) in, equally with trickle, disperse, fill the air the stable alloy cementite: (FeCr)₃C、(Fe·Mo) ₃C、(Cr·Fe) ₂₃C ₆Be present in the crystal boundary of high temperature austenite and between crystal boundary Deng state, except hindering Austenite Grain Growth, and be to obtain even fine-grained martensitic tissue after quenching and the tempering to have laid a good foundation, thereby improve significantly its intensity, hardness and wearability and high-temperature oxidation resistance; Cr, Mo also have the effect that C curve is moved to right and significantly improve quenching degree simultaneously. The Cr constituent content is≤1% the time, its intensity, hardness and impact flexibility are to increase with the increase that contains Cr, but when content 1%＜Cr≤2%, the notched bar impact strength of steel slightly descends, when Cr content＞2%, intensity and impact flexibility 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% the time, 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/cm²Sharply drop to 68.6J/cm², 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 downward trend, should reach strengthening effect, plans as a whole again organic assembly of each element, 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, 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 consumingly growing up of crystal grain; When V content is 0.04%～0.1%, and temperature is 912 ℃～960 ℃, and its austenite crystal changes very little, therefore, and the martensite grain structure after the allocating significantly refinement into and quench of V after martensite and the 300 ℃ of tempering. Undoubtedly, it has greatly improved intensity, hardness and the wearability 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 strong oxidants, and its saturation solubility in ferrite is up to 36%; It has strong deoxidation in molten steel, and obvious high-temperature oxidation resistant effect is arranged, and can significantly improve M simultaneously_S℃ effect, naturally also just synchronously improve M_f℃ the point.

Thereby use the rear lonneal gained martensitic structure of quenching at 280 ℃＜T₂≤ 300 ℃ still keep the hard martensitic structure of former height and anti-wear performance and elevated temperature 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 crystallization 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 Grain-boundary Junctions and has made a concerted effort, 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 greatly improving intensity, hardness and the amount of allocating into of Cr, Ni has not only improved its quenching degree; Particularly multiple alloy carbide and alloyed cementite: VC, Mo₂C、Mn ₃C、 (Fe·Cr) ₃C、(Fe·Mn) ₃C、(Fe·Mo) ₃Deng with trickle, even, fill the air shape and be distributed in the crystal boundary or between crystal boundary, when improving its intensity, hardness, wearability, improved significantly its high temperature resistant property, an amount of adding of Al has improved M effectively_S℃ and Mf ℃ transition point (M_S℃＝320℃，M _f12 ℃ of ℃ ≈), except significantly having reduced the content of retained austenite in martensite, also greatly improved the needed temperature of martensitic decomposition, thus it 280 ℃～still keeping high intensity, hardness, wearability 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 analysis smelts, can adopt Al for carrying out final deoxidation treatment, tapping temperature is 1500 ℃～1520 ℃, treat that spectrum analysis confirms that its chemical analysis meets the requirements, can cast when molten steel temperature is 1470 ℃～1490 ℃. Its concrete production technology is as follows:

1, the casting of blank: going out temperature is 1500 ℃～1520 ℃, and cast temperature is 1470 ℃～1490 ℃, and foundry goods should be unpacked at 250 ℃～270 ℃, carries out immediately 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: after 200 ℃～250 ℃ polishings of local casting flaw band temperature of cast(ing) surface observability are removed, adopt the repair welding of A302 welding rod, weld seam should be continuous, smooth, and welding slag should be removed totally; Postwelding adopts in the lump high speed grinding wheel polishing totally or again to advance stove integral body to overlap, burr, crator and spatter and is preheated to 250 ℃～280 ℃ and carries out above-mentioned mill, benefit work.

3, annealing in process: the blank integral body after will leveling is advanced stove and is heated to 840 ℃～860 ℃ and be incubated 6～8 hours and cool off with stove.

4, machining:

(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 centre line perpendicular to the platform centering and be coated with white powder, in looking for take external diameter as benchmark, press again the seam internal diameter, the inclined-plane, the monolateral 2mm～2.5mm that all stays of both ends of the surface rules.

(3) rough turn: the blank grinding set that will rule hangs on big vertical lathe, presses the line centering and clamps rear rough turn upper surface, seam internal diameter, cooperates inclined-plane and ball external diameter Φ 1900⁰ _-6 Turn-over, the smoothing take face work as basal plane is with external diameter φ 1900⁰ _-6In looking for, more rough turn other end, seam internal diameter and interior inclined-plane.

(4) to the processing of foundry goods cast inside defective: the semi-finished product after rough turn are carried out hundred-percent super spy, to the latent defect found and observability defective dig clearly clean after, use welding gun flame local 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 processed: will surpass and visit qualified semi-finished product 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 semi-finished product grinding set that heat treatment is qualified hangs on big vertical lathe, look for external diameter middle after smoothing, processing upper surface, seam, interior inclined-plane; Turn-over again, take the end face processed as basal plane, in looking for same method, finish turning other end, seam and interior inclined-plane are shaped.

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

Grinding set	Mechanical performance		The accuracy of manufacture		Service time	The grinding set tax included price	Every cover grinding set valency	The grog cost
									Бb	HRC
	Title	N/mm 2									Measured result	End face run-out (mm)	Different moderates (mm)	Hour	Ten thousand yuan/tons	Ten thousand yuan (24T)	Unit/T
Grinding set of the present invention			≥2500	62-67	≤0.04	≤0.3	≥8000	2.52	60.48	0.474
	Domestic existing top grinding set										52-54	0.2-0.3	2-3	3000-4000	3.0	72	1.255
The import grinding set				54-56			6000-7500	12	288	2.5098

The present invention is compared with existing technology, and has following remarkable advantage and obvious techno-economic effect:

1. castability defectives such as pore-free, crackle, burning into sand, the crystalline phase even tissue is stable, eliminated because of the castability defect repair welding and the residual stress due to processing, make the accuracy of manufacture of high level obtain property of a specified duration preservation, thereby avoided under heavily loaded rotary impact and the conduction of strong heat, heat radiation, grinding set is because being subjected to inside and outside distortional stress to converge the phenomenon of wearing and tearing and breaking;

2. the significantly raising of intensity, toughness, wearability and the accuracy of manufacture, except having improved significantly grinding set service life and Vertical Mill delivery stationarity, the more important thing is and be to improve rotating speed, thereby improved mill hourly output and significantly improve and use in one's power product quality and the economic benefit of enterprise;

3. long service life, be 2 times of existing domestic grinding set product, and price only is 84% of domestic product lowest price of the same name, be 21% of World Developed Countries product valency, thereby reduced widely in one's power that the user changes, use the cost of grinding set and the production suspension induced losses that causes because of frequent and the labour cost of removing stage makeup and costume; Undoubtedly, it improves social synthesis's economic benefit widely.

The whole nation reaches industry mutually to be had at least more than 2000, but only 500 calculating. By average 4 Vertical Mills of every family, 4 grinding sets of every grinding machine, 6 tons of every average net weight, be 166 days (about 4000 hours) by existing domestic grinding set maximum service life (MSL), and grinding set per ton is 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 to be changed the grinding set net weight and be: 96000 tons, blank is heavily about: 115200 tons, the grinding set purchase commodity is: 28.8 hundred million yuan; Grinding set is ordered goods, twice round trip expenses of completion acceptance are 2,000,000 yuan (it is 2 people that every factory singly takes advantage of at every turn, and everyone singly takes advantage of 1000 yuan of lump sums of limit to use at every turn); Still the service charge and relevant stopping production economic loss that do not comprise annual secondary stopping production replacing vertical mill sheath.

If use the in one's power wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant of the present invention, in 166 days, also only need so to change once, its cast steel consumption is half of existing grinding set, and the grinding set amount of purchasing 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. Because the present invention in one's power wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant is better than Japan, Germany, Denmark's product including with the outward appearance workmanship, as arrive the RMB price of China by its import: 120,000 yuan/tons, even more preferential 25%, and under the condition of dollar currency rate constant (1: 8.11), 10000 tons of every outlets, then grinding set 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 entirely to refund 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 small investment, instant effect, and it can obtain very significant economic benefit for enterprise and country in a short time. Therefore, it has extensively energetically use value, promotional value and fruitful economic worth.

The specific embodiment

Be further to explain the present invention, existing with the present invention in one's power the wear-resisting non-cracked vertical mill sheath of a kind of high strength heat resistant and manufacturing process provide three examples, implementation technique is as follows:

1, by the present invention in one's power chemical analysis join the stove melting, treat that temperature in the time of 1510 ℃, detects its chemical analysis, except casting at 1480 ℃ behind the 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 upper top dressing dead head cut place through carefully checking 4 large-scale vertical mill sheaths of foundry goods: only have 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, annealing in process: the blank integral body after will leveling enters large-scale desk-top heating by electric cooker to 860 ℃ and is incubated 7 hours to be cooled off with stove.

4, machining:

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

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

3. rough turn: the blank grinding set that will rule hangs on big vertical lathe, presses the line centering and clamps rear rough turn upper surface, seam internal diameter, cooperates inclined-plane and ball external diameter Φ 1900⁰ _-6 Turn-over, rough turn other end, seam internal diameter and interior inclined-plane.

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

5. Q-tempering is processed: will surpass and visit qualified semi-finished product grinding set 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 semi-finished product grinding set that heat treatment is qualified hangs on φ 2.5m vertical lathe, and (φ 1900 with the ball external diameter⁰ _-6) look for finish turning upper surface after the middle clamping, seam, interior inclined-plane; Turn-over is with outer ball diameter φ 1900 again⁰ _-6Face school circle centering, take the end face that processes as basal plane, the processing other end, seam internal diameter and interior inclined-plane are shaped.

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

Chemical analysis and mechanical performance, purposes and the effect list are as follows:

Embodiment number	Chemical analysis											Mechanical performance		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 of φ 1.9 * 0.65m grinding sets, in April, 2002 to 2003, year operation in February was good.
2	0.67	0.49	0.51	1.67	0.17	0.58	0.13	1.53	0.019	0.021	94.21	2910	67	1 of φ 1.9 * 0.65m grinding set, 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 of φ 1.9 * 0.65m grinding set, 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 percentage 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 be used to realizing the wear-resisting non-cracked vertical mill sheath of high strength heat resistant claimed in claim 1, it comprises the following steps:

(1) casting of blank: tapping temperature is 1500 ℃～1520 ℃, cast temperature is 1470 ℃～1490 ℃, 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: after 200 ℃～250 ℃ polishings of local casting flaw band temperature of cast(ing) surface observability are removed, adopt the repair welding of A302 welding rod, weld seam should be continuous, smooth, and welding slag should be removed totally; Postwelding adopts in the lump high speed grinding wheel polishing totally or again to advance stove integral body to overlap, burr, crator and spatter and is preheated to 250 ℃～280 ℃ and carries out above-mentioned mill, benefit work;

(3) annealing in process: the blank integral body after will leveling is advanced stove and is heated to 840 ℃～860 ℃ and be incubated 6～8 hours and cool off with stove;

(4) machining:

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

2. line: with blank hang on platform by work centre line perpendicular to the platform centering and be coated with white powder, in looking for take external diameter as benchmark, 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 grinding set that will rule hangs on big vertical lathe, after pressing the line centering and clamping rough turn upper surface, seam and cooperate the inclined-plane with external diameter band cutter car to 1900 °-6 of φ; The turn-over centering, rough turn other end, seam, interior inclined-plane;

4. to the processing of foundry goods cast inside defective: the semi-finished product after rough turn are carried out 100% surpassing spy, to inherent defective and observability defective dig clearly clean after, use the welding gun fire and fall into local 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 semi-finished product grinding set 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 semi-finished product grinding set that heat treatment is qualified hangs on big vertical lathe, look for external diameter middle through smoothing, processing upper surface, seam, interior inclined-plane; Turn-over again, take the end face of processing as basal plane, in looking for same method, finish turning other end, seam, and interior inclined-plane be shaped.