RU2413026C1 - High strength iron - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: iron contains wt %: carbon 3.85-4.05; silicon 1.95-2.2; manganese up to 0.5; chromium up to 0.1; magnesium 0.03-0.06; lanthanum 0.001-0.01; calcium 0.002-0.007; aluminium 0.003-0.01; zirconium 0.01-0.06; sulphur up to 0.022; phosphorus up to 0.1; iron - the rest. ^ EFFECT: reduced consumption of spheroidising modifier and improved mechanical processability of iron. ^ 3 tbl

Description

The invention relates to metallurgy of foundry, in particular, to the development of compositions of ductile iron with nodular graphite for complex composite castings.

Widely known are ductile iron with spheroidal graphite, containing carbon, silicon, manganese, chromium, magnesium and other elements used for the manufacture of cast parts of machines and mechanisms. These cast irons have high strength and wear resistance, however they have a high cost due to expensive spheroidizing modifiers and difficult machining.

Closest to the proposed composition and achieved properties is cast iron [1] of the following chemical composition, wt.%:

Carbon 3.85-4.05 Silicon 1.95-2.2 Manganese up to 0.5 Chromium up to 0.1 Magnesium 0.03-0.06 Lanthanum 0.001-0.01 Calcium 0.002-0.007 Aluminum 0.003-0.01 Sulfur up to 0.022 Phosphorus up to 0.1 Iron rest

The disadvantage of this cast iron is its high cost due to the high consumption of the expensive spheroidizing Lamet modifier and the difficult machining of castings.

An object of the invention is to reduce the consumption of a spheroidizing modifier and to improve mechanical workability.

The technical result is achieved by the fact that cast iron containing carbon, silicon, manganese, chromium, magnesium, lanthanum, calcium, aluminum, sulfur and phosphorus, additionally contains zirconium in the following ratio of components, wt.%:

Carbon 3.85-4.05 Silicon 1.95-2.2 Manganese up to 0.5 Chromium up to 0.1 Magnesium 0.03-0.06 Lanthanum 0.001-0.01 Calcium 0.002-0.007 Aluminum 0.003-0.01 Zirconium 0.01-0.06 Sulfur up to 0.022 Phosphorus up to 0.1 Iron rest

Analogues containing the distinguishing features of the proposed technical solution were not found. At GAZ OJSC, in the conditions of the foundry laboratory, experimental comparative melts were conducted with the known and proposed cast irons. Cast iron was smelted in an induction furnace IST-016 with acid lining. As a charge, pig iron pig iron, VCh 50 cast iron return, steel waste and ferroalloys were used. Lanthanum, calcium, aluminum and zirconium were introduced as separate ferroalloys.

The metal was overheated in an oven to 1500 ° C and cast iron was poured with four buckets into sand-clay molds to produce “crankshaft compressor” castings with in-mold modification with the Lamet spheroidizing modifier in an amount of 0.57%. The ferrozirconium modifier FS60 Tsr5Mn4 was not introduced into the first bucket. 0.2% FS60 Cr5Mn4 was introduced into the second bucket, 0.4% FS60 Cr5Mn4 was introduced into the third bucket, 0.6% FS60 Cr5Mn4 was introduced into the fourth bucket. The amount of modifier introduced, the chemical composition and microstructure of the obtained castings are shown in tables No. 1, 2, 3.

table number 1 Bucket number The number of additives in the bucket FS60tsr5,% The number of additives in the form "Lamet",% one Without additives 0.57 2 0.2 0.57 3 0.4 0.57 four 0.6 0.57 5 0.8 0.57 6 1,0 0.57

table number 2 Bucket number FROM Si bucket / ex. Mn S P Cr Zr one 3.6 1.47 / 1.77 0.22 0.016 0.06 0.05 0.002 2 3.56 1.56 / 1.84 0.28 0.015 0.06 0.05 0.013 3 3.57 1.67 / 1.89 0.22 0.013 0.06 0.05 0.024 four 3.53 1.83 / 2.17 0.22 0.012 0,07 0.05 0.04 5 3.52 1.92 / 2.22 0.23 0.011 0.06 0.05 0,062 6 3.52 2.0 / 2.37 0.24 0.010 0.06 0.06 0,073

table number 3 Bucket number Microstructure according to GOST 3443-87 Hardness, HB one Graphite: ШГф4,3,5-ВГф3 (15%) - ШГд25,45,90-ШГр2-ШГ10
Metal base: P70 (Fe30) 187 2 Graphite: ШГф4,3,5-ШГд25,45,90-ШГр2-ШГ10
Metal base: П45 (Фе55) 179 3 Graphite: ШГф4,5-ШГд25,45-ШГр1-ШГ10
Metal base: П45 (Фе55) 179 four ShGf4.5-ShGd25.45-ShGr1-ShG10
Metal base: P20 (Fe80) 163 5 Graphite: ШГф4,5-ШГд25,45-ШГр1-ШГ12
Metal base: P15 (Fe85) 156 6 Graphite: ШГф4,5-ШГд25,45-ШГр1-ШГ12
Metal base: P10 (Fe90) 143

In case of intraform modification with a critical amount of the Lamet modifier (with Mg = 5% and Zr = 0.3%), when vermicular graphite (15%) appears in the structure, additional modification with zirconium alloy FS60Cr5 in an amount of 0.2-0.6% at first it reduces the amount of vermicular graphite to zero, and then it improves the shape of graphite from compact to spherical. The amount of ferrite increases from 30 to 80%, and the hardness decreases from 187 to 163 HB.

Industrial casting in the foundry of the “Rear Wheel Hub” castings with the addition of 0.5% FS60 Tsr5Mn4 zirconium alloy and 0.5% Lamet spheroidizing modifier to the mold in the distributing ladle (instead of 0.8% normal) showed satisfactory microstructure and lack of shrinkage porosity on these parts after machining.

The hardness on these castings with the addition of zirconium was 12-15 u.V. less than on castings without the addition of zirconium. The machining laboratory issued a conclusion that the resistance of the cutting tool when processing the rear wheel hubs treated with zirconium alloy increased 3 times.

A smaller amount of zirconium (less than 0.01%) leads to the appearance of vermicular graphite, a larger amount of zirconium (more than 0.06%) is unnecessary, because dramatically reduces the hardness of castings.

Bibliography

1. Holstein, Y.E., Mizin, V.G. Modification and microalloying of cast iron and steel - M .: Metallurgy, 1986. - 272 p.

2. Bagels VB, Berchuk D.N. Increasing the degree of modification of ductile iron // Metallurgy of mechanical engineering. - 2006. - No. 5. - p.31-33.

3. Boldyrev D.A. New effective modifiers and technologies for modifying cast irons // Foundry. - 2006. - No. 12. - c. 9-13.

4. Zinoviev Yu.A. and others. "Cast iron", patent No. 2358032 C22C 37/04, bulletin No. 16 of 06/10/09.

Claims (1)

Cast iron containing carbon, silicon, manganese, chromium, magnesium, lanthanum, calcium, aluminum, sulfur, phosphorus and iron, characterized in that it additionally contains zirconium in the following ratio, wt.%:
carbon 3.85-4.05 silicon 1.95-2.2 manganese up to 0.5 chromium up to 0.1 magnesium 0.03-0.06 lanthanum 0.001-0.01 calcium 0.002-0.007 aluminum 0.003-0.01 zirconium 0.01-0.06 sulfur up to 0.022 phosphorus up to 0.1 iron rest