CN100355926C - Micro alloyed high strength grey cast iron - Google Patents

Abstract

The present invention relates to novel high-strength microalloyed gray cast iron which is especially suitable for producing large-horsepower diesel engine cylinder bodies and other high-strength gray cast iron castings. The microalloying treatment is carried out by optimizing the alloying component design and adding V, N and other elements so as to finally obtain the novel high-strength microalloyed gray cast iron having the advantages of favorable tensile property and favorable processability. The novel high-strength microalloyed gray cast iron comprises the components of the percentage by weight: 2.92 to 3.485 of C, 1.52 to 2.36% of Si, 0.22 to 0.78% of Mn, 0.011 to 0.048% of P, 0.03 to 0.15% of S, 0.15 to 0.50% of Cr, 0.3 to 0.785 of Cu, 0.011 to 0.0985 of Sn, 0 to 0.100% of V and 0 to 0.100% of N. the present invention solves the problem of difficulty in the alloying by adding molybdenum, nickel and other elements in order to enhance the strength at present in the world.

Description

Micro alloyed high strength grey cast iron

Technical field

Micro alloyed high strength grey cast iron of the present invention relates to a kind of novel cast iron materials, particularly relates to a kind of novel gray cast iron material of producing high-power diesel motor cylinder and other high-strength gray cast iron foundry goods that is mainly used in.

Background technology

Along with the control of communications and transportation to overload, the increasingly stringent that transfinites, the sale of large-tonnage heavy truck just increases severely with the speed in every year 60%, and amplification is in first of the automobile industry.Scholarly forecast, China heavily blocked market and will welcome " explosive type " rise period coming years, estimated that average annual growth will reach 17%.Therefore develop as " heart " of automobile and the engine of automobile core technology to high-power and high-speed direction.

Because the high-power diesel motor cylinder need bear higher mechanical stress and thermal stresses in the course of the work, therefore, require its cast iron quality must have homogeneity of fault plane preferably, comprise that performance, tissue, composition are even etc., and excellent mechanical property and castability.The coupon intensity of the graphitic cast iron of general requirement production high-power diesel motor cylinder is greater than 320 MPas, and the coupon diameter is 30 millimeters, and cylinder body body intensity is greater than 240 MPas.

For improve graphitic cast iron intensity, both at home and abroad at design of alloy, the microalloying of high-power diesel motor cylinder and other high-strength gray cast iron castings material and the aspect such as breed and carried out a large amount of research work, obtained certain achievement.At present, produce high-power diesel motor cylinder and other high-strength gray cast iron foundry goods both at home and abroad and mainly still produce, as seen by table 1,2 by adding alloying elements such as a certain amount of chromium, molybdenum, copper and mickel.Along with rising violently of iron alloy such as molybdenum-iron and nickel price in the world wide, producing the cost pressure that high-strength gray cast iron brought by traditional technology becomes one insurmountable barrier of pendulum in face of each manufacturer.Therefore, in order to reduce the production cost of high-strength gray cast iron, be badly in need of a kind of graphitic cast iron of novel high-strength cheaply of invention at present.

The chemical ingredients of domestic graphitic cast iron engine cylinder-body of table 1 and cylinder cap

Sequence number	Chemical ingredients (weight percent)								Foundry goods
										C	Si	Mn	P	S	Cr	Cu	Mo
	1	3.0-3.3	1.8-2.2	0.5-1.0	≤0.15	≤0.13													X105, X100 cylinder body,lid
2									3.0-3.3	1.8-2.2	0.5-1.0	≤0.15	≤0.13	0.15-0.35	0.4-0.7		TheX485 cylinder cap
	3	3.2-3.4	1.8-2.0	0.5-0.8	≤0.07	≤0.12		0.4-0.6										0.4-0.6	Cylinder cap
4									3.2-3.4	1.9-2.1	0.6-0.9	≤0.08	≤0.12	0.25-0.35			The EQ-140cylinder cap
	5	3.25-3.45	1.8-2.2	0.6-0.9	≤0.08	≤0.1	0.25-0.35	0.35-0.45											R1000 cylinder body, cylinder cap
6									3.15-3.3	1.6-2.1	0.75-1.0	≤0.2	≤0.1	0.2-0.4	0.5-1.0	0.3-0.5	Cylinder cap
	7	3.15-3.4	2.1-2.5	0.6-0.75	0.06	0.06	0.25-0.35	0.3-0.4											The 475Q cylinder body
8									3.2-3.5	2.0-2.4	0.6-1.0	≤0.15	≤0.1	0.3-0.4	0.7-1.0		195 cylinder caps

The chemical ingredients of external graphitic cast iron engine cylinder-body of table 2 and cylinder cap

Sequence number	Country origin	Company	Foundry goods	Chemical ingredients (weight percent)										Tensile strength (MPa)
															C	Si	Mn	P	S	Cr	Mo	Cu	Sn	Ni
				1	Japan	Isuzu Motors	Cylinder cap	3.2	2.28	0.73	0.041	≤0.1	0.17
2	Germany	M.A.N	The single cylinder lid											3.4-3.5	1.9-2.0	0.6-0.7	≤0.1	≤0.13	0.15	0.25	0.2			≥250
				The twin-tub lid	3.5-3.55	1.7-1.8	0.6-0.65		≤0.13	0.3															0.75	≥250
			3											Germany	Moto-rtey	The twin-tub lid	3.4-3.5	1.8	0.65	≤0.1		0.3	0.35-0.45					1.0-1.1	≥280
4	Germany	M.W.M		The single cylinder lid	3.25-3.45	1.7-1.9	0.6-0.8	≤0.1	≤0.1	0.2-0.3			0.08												0.4-0.6	≥250
			5											Britain	Rolls-Royce	Cylinder body	3.3-3.5	1.8-2.4	0.8	≤0.1	≤0.06	0.25-0.4	0.4	0.5					≥260
6	France	C.A		Cylinder cap	3.3-3.4	1.8-2.2	0.6-0.7	≤0.15	≤0.15	0.2-0.3															0.5	≥250
			7											The U.S.	John.Deere	Cylinder cap	3.0-3.4	1.7-2.25	0.6-0.9	≤0.2	≤0.12	0.2-0.4	0.3-0.5	0.75-1.0				1.0-1.2	≥300
Cylinder cap	3.2-3.6	2.0-2.5		0.4-0.9	≤0.15	≤0.15	0.2-0.4	0.3-0.5	0.75-1.0		1.0-1.2	≥225

Summary of the invention

The objective of the invention is: under the prerequisite of the tensile strength that high-strength gray cast iron had that guarantees present adding molybdenum or molybdenum and nickel, a kind of elements such as molybdenum and nickel that replace by microalloying are provided, reduce the micro alloyed high strength grey cast iron of the production cost of high-strength gray cast iron greatly.

Above-mentioned purpose of the present invention is to realize like this, accompanying drawings is as follows: a kind of micro alloyed high strength grey cast iron comprises elements such as C, Si, Mn, P, S, Cr, Cu and Sn, by optimizing these elements, added micro-V and N element again, its weight percent chemical ingredients is:

C：2.92～3.48；Si：1.52～2.36；Mn：0.22～0.78；P：0.011～0.048；

S：0.03～0.15；Cr：0.15～0.50；Cu：0.3～0.78；Sn：0.011～0.098；

V：0～0.100；N：0～0.100。

The as-cast structure of the novel micro alloyed high strength grey cast iron of the present invention is an A type graphite, 4～6 grades; Content of pearlite in alloy 〉=95%, as depicted in figs. 1 and 2.Diameter is coupon tensile strength 〉=320 MPas of 30 millimeters.

The novel micro alloyed high strength grey cast iron of the present invention is compared with at present traditional high-strength gray cast iron, the major technique advantage that has is: at present traditional high-strength gray cast iron adds a large amount of molybdenum or molybdenum and nickel element for the tensile strength that improves graphitic cast iron is essential, and the present invention only need add the vanadium and the nitrogen element of minute quantity, just can reach the tensile strength level that adds a large amount of molybdenums or molybdenum and nickel.The Financial cost advantage of being brought by the major technique advantage will make the production cost of high-strength gray cast iron reduce greatly.Because the price of molybdenum-iron is in sharp increase at present, the price of current molybdenum-iron has increased to about 430,000 RMB/tons.Produce the high-strength gray cast iron molybdenum-iron that generally will add 4 kilograms per ton, cost is 1720 RMB.And novel micro alloyed high strength grey cast iron of the present invention additional cost per ton is only about 300 RMB, like this per ton reducing cost about 1400 RMB.The economic benefit that large-scale production brought will be very considerable.

Marginal data

Fig. 1 is the graphite form (A type graphite is main) of the novel micro alloyed high strength grey cast iron of the present invention.

Fig. 2 is the matrix (perlite+1% ferrite) of the novel micro alloyed high strength grey cast iron of the present invention.

Fig. 3 is a high-power Dao Yici diesel motor cylinder outward appearance photo.

Fig. 4 is the cylinder body body graphite form (A type graphite is main) of producing with the novel micro alloyed high strength grey cast iron of the present invention.

Fig. 5 is the cylinder body body matrix of producing with the novel micro alloyed high strength grey cast iron of the present invention (perlite+1% ferrite).

Embodiment

Below in conjunction with the accompanying drawing illustrated embodiment, further specify particular content of the present invention.

Embodiment one: the present invention optimizes the design of alloy of graphitic cast iron and the positively effect of microalloying is to replace elements such as molybdenum and nickel, and improves the tensile strength of graphitic cast iron, and its effect is fairly obvious, and tensile strength is significantly improved.The composition and the mechanical property of novel micro alloyed high strength grey cast iron are as shown in table 3.

The composition of the novel micro alloyed high strength grey cast iron of table 3 and mechanical property

Test piece number (Test pc No.)	Chemical ingredients (weight percent)											Mechanical property
														C	Si	Mn	P	S	Cr	Mo	Cu	V	Sn	N	Tensile strength (MPa)	Hardness (HB)
	1 2 3 4 5 6 7 8 9 10	3.27 3.15 3.05 2.92 3.31 3.48 3.27 3.25 3.41 3.28	1.76 1.80 1.99 2.06 2.10 2.36 2.15 2.09 1.82 2.12	0.34 0.72 0.51 0.25 0.35 0.61 0.78 0.66 0.54 0.44	0.016 0.034 0.020 0.042 0.041 0.039 0.028 0.033 0.048 0.032	0.09 0.11 0.12 0.08 0.07 0.14 0.04 0.13 0.15 0.06	0.29 0.20 0.35 0.48 0.50 0.49 0.33 0.45 0.39 0.18	/ 0.2 / / / / / / / /	0.55 0.63 0.50 0.51 0.75 0.62 0.50 0.60 0.58 0.56	/ / 0.017 0.035 0.051 0.048 0.088 0.100 0.075 0.100	/ 0.06 0.02 0.018 0.042 0.051 0.066 0.07 0.09 0.03	/ / 0.007 0.0092 0.01 0.05 0.09 0.082 0.100 0.094	300 330 340 365 360 360 370 390 375 395														208 239 228 229 231 230 233 240 237 242

Annotate: (1) No. 1 sample is a rolled products of ordinary high-strength graphitic cast iron; No. 2 samples are for adding the molybdenum high-strength gray cast iron; No. 3～No. 10 sample is the novel micro alloyed high strength grey cast iron of the present invention.

(2) 150 and 50 kilograms of medium-frequency induction furnaces are adopted in the preparation of sample respectively.1480～1520 ℃ of water outlets add 75 ferrosilicon and breed in casting ladle, cast φ 30 * 280mm round bar shape coupon is produced tensile strength coupon and metallographic specimen from this coupon in sand mold.

Embodiment two

Produce the Dao Yici cylinder body with the novel micro alloyed high strength grey cast iron of the present invention as a trial in a vapour Foundry Inc..High-power Dao Yici diesel motor cylinder complex structure, wall thickness difference is big,position 5～6mm that it is thin, thick position reaches 20～70mm, is the high-strength gray cast iron spare of typical inhomogeneous wall thickness, as shown in Figure 3.Its thick major part in use since intensity hang down under high mechanical stress and thermal stresses and ftracture easily.Adopt the novel micro alloyed high strength grey cast iron of the present invention to make this cylinder body, satisfying under the prerequisite of its requirement of strength design, will reduce its production cost greatly.Cylinder body anatomical results to trial production sees Table 4, and the metallographic structure photo is seen Fig. 4 and Fig. 5.

Table 4 adopts the result after the cylinder body of the novel micro alloyed high strength grey cast iron trial production of the present invention is dissected

The cylinder body that adopts the novel micro alloyed high strength grey cast iron of the present invention to produce as can be seen from Table 4, its tensile strength can satisfy requirement of strength design fully.Simultaneously, the intensity good uniformity, and hardness is lower than and adds the molybdenum high-strength gray cast iron, and this will help improving the processing characteristics of cylinder body.In addition, supercooled graphite and carbide do not occur at positions such as the wedge angle of cylinder body and overlaps, graphite form is good.Thereby show that the novel micro alloyed high strength grey cast iron of the present invention that adopts elements such as adding V, N to carry out the microalloying processing can replace traditional high-strength gray cast iron of elements such as adding molybdenum, nickel fully, produces high-power diesel motor cylinder and other high-intensity castings of gray cast iron of same intensity performance level.

Annual production as a high-power diesel motor cylinder manufacturing enterprise is 100,000 cylinder bodies, will be with 30,000 tons of molten iron, as adopt novel micro alloyed high strength grey cast iron of the present invention, will save about cost 4,000 ten thousand RMB, simultaneously, will save world's narrow resources such as a large amount of molybdenums, nickel for country.

Claims (1)

Translated fromChinese

1.一种微合金化高强度灰铸铁包括C、Si、Mn、P、S、Cr、Cu和Sn等元素，其特征在于添加了微量的V和N元素，其重量百分比化学成分为：1. A kind of micro-alloyed high-strength gray cast iron comprises elements such as C, Si, Mn, P, S, Cr, Cu and Sn, is characterized in that adding trace V and N elements, and its weight percent chemical composition is:C：2.92～3.48；      Si：1.52～2.36；  Mn：0.22～0.78； P：0.011～0.048；C: 2.92～3.48; Si: 1.52～2.36; Mn: 0.22～0.78; P: 0.011～0.048;S：0.03～0.15；      Cr：0.15～0.50；  Cu：0.3～0.78；  Sn：0.011～0.098；S: 0.03～0.15; Cr: 0.15～0.50; Cu: 0.3～0.78; Sn: 0.011～0.098;V：0.035～0.100；    N：0.01～0.100。V: 0.035～0.100; N: 0.01～0.100.

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