CS254887B1 - Cast iron with high abrasion resistance - Google Patents

Abstract

High resistance cast iron abrasion for the production of exposed parts intensive abrasive wear particles such as crushers % slag, has a composition of 2.8 to 3.1 wt. % carbon, 24.0 to 26.0 wt. of chromium, 0.3 up to 1.0 wt. % manganese, 0.3 to 1.0 wt. % silicon, 0.1 to 0.2 wt. titanium, 0.1 to 0.2 wt. % aluminum and 0.05 to 0.1 wt. boron. For more massive cast iron castings further containing from 0.4 to 0.6 wt. nickel a 1.0 to 1.5 wt. molybdenum. As technological The cast iron additive contains cerium in quantity from 0.05 to 0.1 wt.

Description

BACKGROUND OF THE INVENTION The present invention relates to cast iron with high abrasion resistance for the manufacture of parts subjected to intensive wear by abrasive particles.

A number of cast iron variants of the Fe-Cr-C system with an increased chromium content and optionally with the addition of other elements are currently used for this purpose. The reason for the higher chromium content is that from about 10% of the weight of chromium in these cast irons crystallizes at the end of their primary crystallization as one of the quasieutectic phases of hexagonal carbide M? C ₃ , which has higher hardness than cementite. tendency to brittle fracture.

They are used in hardened or low tempered conditions. This implies, among other things, the requirement of their good hardenability in the production of components of larger weights? for this purpose, the basic composition is usually modified by the addition of molybdenum, nickel or copper, which improves their hardenability. Abrasion resistance is most strongly influenced by the carbon content of cast iron, but this is limited by the concentration corresponding to the position of the interface between the austenitic field and the primary crystallization area of M ^ C ₃ at a given overall cast iron composition. the tendency of cast iron to brittle fracture and the abrasion resistance of cast iron decreases. ”

This disadvantage is overcome by the high abrasion resistant cast iron according to the invention, containing from 2.8 to 3.1% by weight. % of carbon, from 24.0 to 26.0 wt. %, from 0.3 to 1.0 wt. % manganese and from 0.3 to 1.0 wt. silicon. It is an object of the invention that the cast iron further comprises aluminum in an amount of from 0.1 to 0.2% by weight, titanium from 0.1 to 0.2% by weight, boron from 0.05 to 0.1% by weight. and as a technological additive cerium from 0.05 to 0.1 wt. According to another feature, the high hardenability cast iron intended for larger castings further comprises nickel in an amount of 0.4 to 0.6% by weight. and molybdenum from 1.0 to 1.5 wt.

The advantage of the cast iron according to the invention is about 30% higher abrasion resistance than the corresponding type of cast iron used for the above mentioned purposes so far, with comparable or higher resistance to brittle fracture.

The cast iron according to the invention is the result of a theoretical study of the primary crystallization of cast irons of this type and the effect of thermodynamic interaction between the atoms of the alloying elements on the mechanism of this crystallization and the displacement of the above mentioned interface. On the one hand, the alloying elements favorably influence the nucleation process of cast iron by increasing the dispersion of both the matrix and the eutectic phases, thereby reducing its tendency to brittle fracture and increasing the abrasion resistance. Furthermore, the alloying elements form hard carbides which crystallize in the matrix and thereby increase its abrasion resistance, while not increasing the tendency of the cast iron to brittle fracture due to its high dispersion.

For this purpose, the cast iron is alloyed with aluminum, titanium and boron in the variant for smaller castings, and in the second variant, characterized by high hardenability and intended for the production of more massive castings, in addition nickel and molybdenum. Preferably both technological castings 0.05 to 0.1 wt. cerium, which positively affects their nucleation mechanism, thereby improving their mechanical properties and abrasion resistance.

The cast iron with high abrasion resistance is illustrated in more detail in the following examples. By way of comparison, the composition and properties of Cr 25 cast iron used for the production of Wageneder slag shredders are shown. Table 1 shows the composition of the comparative cast iron Cr 25 (designated A) and the cast iron according to Item 1 (Item B) and Item 1 + 2 (Item C).

Table 1

Cast iron

Cr Mn Si

Ti Al B

Ni

Mo

AND 2.91 24.97 0.76 0.84 (B) 2.90 25.02 0.68 0.77 0.19 0.14 0.11 C 2.95 24.95 0.70 0.72 0.20 0.09 0.09 0.62 1.30

Table 2 shows the properties of all three cast irons in the cast state (designation 1), annealed softly at 800 ° C / 4 hrs / spec (designation 2), annealed and hardened 950 ° C / 1 hours / air (marked 3) and annealed soft and hardened 950 ° C / 1 hour / spec 1 ° C / min. (labeled 4).

In addition to the abrasion test values, the hardness of the material is an important material reagent as it significantly affects the economics of part machining.

The property values after very slow cooling from the quenching temperature simulate the effect of larger casting thicknesses on these properties.

Table 2

Cast iron Thermal treatment Hardness HV 10 Max. deflection (mm) Abrasion residue (g) AND 1 525 0.55 0.35 560 0.60 0.36 2 390 - - 425 - - AND 3 734 0.45 0.35 792 0.51 0.37 4 525 0.73 0.48 570 0.82 0.50 1 579 0.47 0.27 620 0.52 0.29 2 345 - - (B) 373 - 3 613 0.52 0.24 681 0.54 0.26 4 317 0.63 0.40 357 0.85 0.42 1 572 0.17 627 - 0.18 2 464 - . - C 503 - - 3 627 0.36 0.16 707 0.49 0.18 4 357 0.55 0.36 402 0.68 0.40

The cast iron according to the invention can be used to produce components such as strips or hammers of crushers for grinding slag or limestone, lining hopper chutes on blast furnace bell shutters, substrate containers, sweep wheel shovels, exhaust and granulation pump parts and the like.

Claims (2)

SUBJECT OF THE INVENTION 1. Cast iron with high abrasion resistance, containing from 2.8 to 3.1 wt. % of carbon, from 24.0 to 26.0 wt. % chromium, from 0.3 to 1.0 wt. % manganese and from 0.3 to 1.0 wt. % of silicon, characterized in that it contains aluminum in an amount of from 0.1 to 0.2% by weight, titanium from 0.1 to 0.2% by weight, boron from 0.05 to 0.1% by weight. and as a technological additive cerium from 0.05 to 0.1 wt. 2. The cast iron according to claim 1, further comprising nickel in an amount of from 0.4 to 0.6% by weight. and molybdenum from 1.0 to 1.5 wt.