DE1814946B2 - USE OF A CAST IRON ALLOY FOR CASTINGS WITH LAMELLAR GRAPHITE, HIGH TOUGHNESS AND HIGH THERMAL CONDUCTIVITY - Google Patents

Description

The silicon contents are in the casting with the cast iron alloy to be used according to the invention remarkably low and are compared to castings of the same wall thickness from common nonna'em Cast iron greatly reduced. So up to a value of 1.6% silicon in the casting is made from normal Gray cast iron, on the other hand, is a casting made of tough gray cast iron with one that is at least half the size Silicon value poured off. Is z. B. a casting made of normal gray cast iron with 1.5% silicon content In contrast, when casting the same casting made of tough gray cast iron, at most half of this value, i.e. a maximum of 0.75% silicon is required.

Castings made of a cast iron alloy with a silicon content of above 1.6% are tough Cast iron with a silicon value lower by at least 0.8% absolute. Is z. B. a Casting made of conventional gray cast iron with 2.5% silicon, the same casting made of tough Cast iron with a maximum of 1.7% silicon.

How high the absolute silicon content of the casting made of normal gray cast iron is set in the individual case must be, is familiar to the person skilled in the art. It should be noted that this content is known also depends on the wall thickness of the casting. After determining the silicon content that is required for the Production of normal gray cast iron is required, as in the individual case of tough gray cast iron Silicon content is to be set.

An inoculation treatment known per se for gray cast alloys is expedient according to the invention made to be used cast iron alloy melt. The only thing to note here is that through the seed alloy, which is generally based on silicon, a certain silicon content in the Cast iron melt is introduced. This silicon value that gets into the melt via the inoculant must be taken into account for the final silicon value. It is therefore a correspondingly low silicon content Provide base melt. In particular, these ratios are at extremely low final silicon contents to take into account the cast iron melt, in which, if necessary, the entire silicon content when inoculated into the Cast iron melt reaches

The cast iron alloy to be used according to the invention can also be done in a manner known per se and taking into account the requirements for such cast alloys high purity of the matrix applicable laws can be alloyed, as is searched for in DT-AS 1250643 is detailed. That is, the alloying element

ίο must have no or only a very weak carbide stabilizing agent Have an effect, it should have a lattice constant similar to iron to avoid distortion of the To a large extent avoid ferrite lattice and finally the alloy element should not have any connection with carbon enter.

The invention is illustrated by the examples below explained in more detail.

Examples Ibis5

In each case 1350 kg of cast iron of the analysis given in Table I were placed in a 1.5 t mains frequency induction furnace melted and tapped at 1490 ° C each time. The cast iron melt became castings the ongoing production, such as thin-walled housing parts, cast. Vaccination of the individual Cast iron was melted each time it was tapped the oven by adding a commercially available inoculant to the composition

60-65% silicon
5-7% manganese
5-7% zirconium
1% aluminum

Remainder iron.
35

Samples for the Tensile strength (short proportional rod according to DIN 50 125 B) and for the 'impact module (according to ISO proposal No. 1197). Table I gives the mechanical property values for the respective Composition of the cast iron alloy.

Table I.

at ° / "Mn 0.050 % P % Si % c train Impact Toughness game 0.042 strength module α st code Z 0.036 if 0.034 (kp / ram ^! ) (cmkp / cm ') 1 0.55 0.022 0.023 1.22 3.65 21.8 8.0 1,200 2 0.92 0.018 1.28 3.75 20.5 6.8 1.170 3 0.69 0.031 1.25 3.62 21.9 7.6 1.178 4th 0.51 0.027 1.08 3.44 24.2 9.7 1.220 5 0.82 0.022 1.21 3.72 19.8 6.8 1.180

From the examples compiled in Table I. it can be seen that from cast iron melts of high purity and with manganese contents greater than 0.3% and up to 1% manganese and castings with a sulfur content of less than 0.06% with a high toughness index can be produced. The manganese-sulfur ratio is in the range to be used according to the invention Cast iron alloys greater than 10: 1.

Demeeeenüber will be with comparable samples Made of conventional gray cast iron with carbon contents of 3.6-3.8% for the impact module as a characteristic obtained significantly lower values for the toughness of cast iron with lamellar graphite. In Table II the values determined on test rods made of normal gray cast iron are listed. The 30 mm test rods were poured under the same conditions as in Examples 1-5 and samples for the Tensile strength and the modulus of impact manufactured.

5 II % s % P 18th 14th 946 H Toughness . 6th code Z Tabel % Mn 0.110 0.180 % Si % c train Impact 0.960 0.125 0.165 strength CB module around 1.020 (kp / mm ^! ) (cmkp) 0.85 2.10 3.65 22.1 3.9 0.76 2.15 3.78 18.5 4.0

Claims (1)

2.5 to 3.8% carbon, claims: below 0.08%, preferably below 0.04% phosphorus, below 0.08%, preferably below 0.04% chromium, 1. Use of a cast iron alloy, preferably less than 3 ml / 100 g hydrogen, starting from 5 below 0.06% preferably below 0.03% sulfur, 2.5 to 3.8% carbon, the remainder iron with the lowest levels of interfering elements, below 0.08%, preferably below 0.04% phosphorus, such as arsenic, boron, antimony, lead, tellurium, selenium,
below 0.08%, preferably below 0.04% chromium, less than 3 ml / 100 g hydrogen, and a silicon content that is around 0.8% absolute below 0.06%, preferably below 0.03% sulfur, up to half that of iron with the lowest content in castings with the same wall remainder in sturgeon starch from common cast iron, such as arsenic, boron, antimony, lead, tellurium, is reduced, and a selenium manganese content of more than 0.3 to 2.25% as a material for castings and a silicon content that by about 0.8% with a pearlitic structure and lamellar graphite, absolutely up to half of that of castings with the same high toughness in the as-cast state (measured rather wall thickness from conventional cast iron necessary according to ISO proposal 1197), which is reduced compared to that of the silicon content is, and a conventional cast iron comparable tensile strength about manganese content of more than 0.3 to 2.25%, than is doubled and high thermal conductivity, the ge-Werkstoii for castings with a pearlitic structure compared to the one usual cast iron alloy with lamellar graphite formation and high toughness ₂ o equivalent graphite content by about a third er in the cast state (measured according to ISO proposal is increased, according to main patent 16 08 239 with the stipulation 1197), which compared to that of conventional cast iron that the ratio from manganese to sulfur greater comparable tensile strength is roughly doubled than is 10: 1 to 300: 1. and high thermal conductivity, which compared to the As appropriate considering the manganese / a conventional cast iron alloy with a comparable sulfur ratio to be used cast iron graphite content increased by about a third Alloys with lamellar graphite formation is, according to main patent 16 08 239, with the proviso that such compositions are within the that the ratio of manganese to sulfur was shown to be rich to 2.25 ° ₀ , which at high greater than 10: 1 to 300: 1. Purity of the matrix a manganese content of more 2. Have use of a cast iron alloy according to 30 as 0.3 ° _o and up to 1 ° _o . Castings cast in claim 1 with the proviso that the manganese content of iron alloys with manganese contents of this range more than 0.3 to 1%, preferably 0.6 to _"0 have high mechanical property values for the amounts, for the purpose according to claim 1 . Toughness index and the impact modulus. Particularly favorable values with regard to toughness index 35 number and the impact module of castings from the According to the invention to be used cast iron alloys are achieved if the manganese content is higher than It is known that cast iron alloys are largely 0.3 ° ₀ and up to 0.6 "". The unstrained lattice of the iron matrix as the workings are used in particular for manufacture material for castings of high toughness and high 40 of cast iron melts for casting thin-walled As-cast thermal conductivity used in lamellar housing parts. Use graphite training. This cast iron to achieve optimal toughness values should that with flake graphite is characterized by a particularly low ratio of manganese to sulfur, in particular containing carbide-forming and carbide-stabilizing iron components with manganese contents of more than 0.3% ^and up to 1%, and is composed of 45 in the cast iron to be used according to the invention from 2.5 to 3.8% carbon, below 0.08? _o Phosphorus, alloy must be greater than 10: 1 and for practically less than 0.08 % chromium, less than 3 ml / 100 g hydrogen, table purposes not more than 300: 1,
below 0.06% sulfur, below 0.3% Mn, remainder iron The cast iron to be used according to the invention with the lowest content of interfering elements, as well as an alloy of high purity of the base material, a silicon content that is around 0.8% up to half 5 ° correct manganese / sulfur ratio of greater than that of castings with the same wall thickness of 10: 1 and up to 300: 1 and an increased silicon content of over 0.3% required for conventional cast iron and up to 1 ° ₀ , preferably up to 0, 6% is deducted (DT-AS 12 50 643). the manganese content is determined by the good casting technology The main patent 16 08 239 provides for the use of properties of normal cast iron and such a cast iron alloy of the same purity as 55 possible the casting of castings with a lamellar base, the manganese content of which is greater than 0.3% graphite formation with high values for the toughness up to 2.25%, preferably up to 1.75% speed index and the impact modulus. It can be manganese amounts. It has been found that, in addition, workpieces with high thermal conductivity produce high-purity cast iron alloys and an increased manganese toughness index of more than 0.3% to 2.25% compared to cast iron parts. The toughness content by adhering to a certain index is understood here:
ratio of manganese to sulfur cast parts more optimal mechanical strength and toughness parameters ^ = * ° g ⁰ ^ ~ ^ ~ W can be obtained. The invention therefore sees as a work log _ΰΒ
material for castings with lamellar graphite formation, 65 high toughness and high thermal conductivity in In this equation, around the impact modulus, -Cast using a cast iron alloy measured in kgf · cm / cm ³ and the tensile strength, Ge before. consisting of measurements in kp / mm ² .