CS258910B1 - Ductile cast iron for components resistant to adhesive wear - Google Patents

Abstract

Ductile iron, containing carbon 3.0 to 3.8%, silicon 2.0 to 3.5, manganese 0.2 to 1.5%, sulfur up to 0.03%, magnesium up to 0.1% and rare earth elements up to 0.1% by weight, further contains chromium 0.03 to 0.3%, molybdenum 0.03 to 0.5%, vanadium 0.03 to 0.5%, nickel 0.1 to 2.5%, copper 0.1 to 1.5%, phosphorus 0.03 to 0.3%, tin up to 0.15%, antimony » up to 0.03%, the balance iron. It is desirable that castings from said cast iron or machined parts from these castings are subsequently heat treated so that they are subjected to recrystallization annealing and then spheroidization annealing. This achieves a structure consisting of granular graphite embedded in a ferritic-carbide or ferritic base metal mass with a resulting hardness not exceeding approximately 280 Brinell units. In comparison with the brass used so far, the ductile iron castings produced in this way are characterized by increased wear resistance under sliding friction conditions, and a lower weight on average of approximately 12%. The proposed solution brings significant savings in copper and significantly higher production efficiency.

Description

The present invention relates to a ductile iron having a basic chemical composition of carbon 3.0 to 3.8%, silicon 2.0 to 3.5%, manganese 0.2 to 1.5%, sulfur to 0.030%, magnesium dc 0.10% or rare earth elements up to a total of 0.1% by weight, suitable for wear-resistant components, in particular for roller bearing components such as bearing cages and guide rings.

For the production of roller bearings, cast or heavily formed brass has so far been used. Brass has good sliding properties, satisfactory mechanical properties and good machinability. The disadvantage of these materials is lower abrasion resistance and high copper content, mainly; 58 to 60 wt. The use of brass on bearing cages is costly and therefore economically disadvantageous. Due to the steadily increasing cost of using brass, the cost of producing such cages is increasing.

It is an object of the present invention to eliminate, or at least substantially reduce said drawbacks by the ductile cast iron according to the invention. The nodular iron of the above-mentioned basic composition further comprises chromium 0.03 to 0.3%, molybdenum 0.03 to 0.5%, vanadium 0.03 to 0.5%, nickel 0.1 up to 2.5%, me3 0.1 to 1.5%, phosphorus 0.03 to 0.3%, tin traces up to 0.15%, antimony traces up to 0.03%, the rest iron., all considered % by weight.

It is desirable that castings of said cast iron or machined parts of said castings be subsequently heat treated to undergo annealing with recrystallization followed by spheroidization annealing. This achieves a structure consisting of granular graphite embedded in a ferritic-carbide or ferritic metal matrix with a resulting hardness not exceeding about 280 Brinella units.

The advantage of the proposed solution according to the invention is that the chemical composition of the ductile cast iron and the optimum structure of its matrix have some significant advantages over the brass used hitherto. It is mainly an increase in wear resistance of components under sliding friction conditions and a reduction in their weight by approximately 12% on average, copper savings and a significantly higher production efficiency.

Example # 1:

800 mm outer spherical roller cage castings having chemical composition carbon 3,62%, silicon 2,50%, sulfur 0,011%, magnesium 0,045%, cerium 0,01%, manganese 0,64 i, phosphorus 0,051%, nickel 0.25%, chromium 0.15%, copper 0.30 i, molybdenum 0.03%, vanadium 0.11%, tin 0.006%, antimony 0.03%, are gravity cast into the sand mold using external coolers .

Cage castings are heat treated using recrystallization annealing. They are austenitized at a temperature in the range of 940 to 960 ° C for 4 hours and cooled in air. This is followed by spheroidization annealing at a temperature of 690 to 710 ° C with a duration of 8 hours and cooling in air.

The resulting structure of castings after heat treatment consists of a mixture of imperfectly and perfectly grained perlite; casting hardness is 220 units Brinella.

Example 2:

Double row spherical roller cage castings having an outside diameter of 205 mm having a chemical composition of 3.65% carbon, 2.25% silicon, 0.010% sulfur, magnesium 0.053%, cerium 0.02%, manganese 0.26%, phosphorus 0.035%, nickel 0.15%, chromium 0.06%, copper 0.27%, molybdenum 0.04%, vanadium 0.06%, tin 0.007%, antimony 0.02%, are cast by gravity into the sand mold.

Cage castings are heat treated using recrystallization annealing. They are austenitized at a temperature in the range of 930 to 950 ° C for 3 hours with cooling in air. This is followed by spheroidization annealing at a temperature of 700 to 720 ° C with a duration of 5 hours and cooling in air.

The resulting structure of the casting after heat treatment is ferritic-pearlitic with a content of 25% imperfectly and perfectly grained pearlite; casting hardness is 160 units Brinella.

Example 1 and e:

Guide rings with outside diameter of 113 min double row spherical roller bearings, made of 0 93/119 x 140 mm sleeve casting, having chemical composition carbon 3,54%, silicon 2,71%, sulfur 0,012%, magnesium 0,048%, cerium 0,003 %, manganese 0.42%, phosphorus 0.053%, nickel 0.3%, chromium 0.06%, had 0.50%, molybdenum 0.04%, vanadium 0.07%, tin 0.021%, antimony 0.03 % are cast by gravity into the sand mold.

Housing castings are not heat treated. The resulting structure consists of 80% predominantly lamellar pearlite. The hardness is 260 units of Brinella.

The proposed examples do not exhaust all possibilities of realizing the invention both in the field of composition and in the casting method, where it is possible to apply centrifugal casting, shell casting and the like.

Claims (1)

Ductile cast iron for wear-resistant parts, in particular roller bearing parts, eg bearing bushes and guide rings having a basic chemical composition of carbon 3.0 to 3.8%, silicon 2.0 to 3.5%, manganese 0.2 to 1, 5%, sulfur up to 0.030%, magnesium up to 0.10%, or rare earth elements up to a total of 0.1%, characterized in that it also contains chromium 0.03 to 0.3%, molybdenum 0.03 to 0.5% , vanadium 0.03 to 0.5%, nickel 0.1 to 2.5%, copper 0.1 to 1.5%, phosphorus 0.03 to 0.3%, tin to 0.15%, antimony to 0.03%, the rest iron, all in% by weight.