CZ279637B6 - Cast iron resistant to abrasive wear - Google Patents

Abstract

Abrasive wear-resistant cast iron contains 1.8 to 3.5% by weight. % carbon, 0.4 to 1.2 wt. % manganese, 0.3 to 0.8 wt. % silicon, 20 to 29 wt. % of chromium, 0.01 to 0.05 wt. % phosphorus, 0.01 to 0.03 wt. % sulfur, 0.05 to 0.2 wt. % vanadium, 0.01 to 0.1 wt. zirconium, 0.002 to 0.006 wt. boron and 0.01 to 0.1 wt. aluminum. It may also preferably comprise from 0.3 to 2.0% by weight. % molybdenum and / or 0.3 to 1.0 wt. nickel

Description

The invention relates to an abrasive wear-resistant cast iron comprising 1.8 to 3.5% by weight, carbon, 0.4 to 1.2% by weight, manganese, 0.3 to 0.8% by weight, silicon, 20 to 29% by weight, chromium, 0.01 to 0.05 wt.%, phosphorus, 0.01 to 0.03 wt.%, sulfur, which is particularly suitable for dynamically stressed machine parts subjected to intense abrasive wear.

BACKGROUND OF THE INVENTION

Currently, low and medium alloy steels with a tempered structure are used for dynamically stressed components such as bounce bars, crusher jaws and grinding plates of mills that are exposed to intense abrasive wear when crushing ores, coal, aggregates, clinker and the like martensite. Mechanical properties such as strength and impact strength are high, but the values of relative abrasive wear resistance ψ max are low. /

Also known are chromium-alloyed podeutectic and eutectic steels and cast irons having a composition of 1.2 to 3.5% by weight, carbon, 15 to 31% by weight, chromium, with a high value of relative abrasive wear resistance W = 2.7 to 3.6 . The disadvantage of these materials is the high brittleness and low impact toughness value of not more than 3 J.cm in the calenated and tempered state. During crystallization of the casting, a trans-crystallization zone is formed, in which cracks occur during hardening. Under dynamic loading of castings, cracks spread until premature fractures occur. The above alloys are also susceptible to central porosity, from which cracks propagate and fractures of stressed components occur.

SUMMARY OF THE INVENTION

The above disadvantages are largely overcome by the abrasive wear-resistant cast iron containing 1.8 to 3.5% by weight, carbon, 0.4 to 20 to 29%

0.03% by weight of sulfur according to the invention. Its essence is it further contains 0.05 zirconium, 0.002 to aluminum.

% By weight, manganese, 0.3 to 0.8% by weight, silicon, by weight, chromium, 0.01 to 0.05% by weight; 0.01 to 0.1 wt.

0.01 to 0.1 wt.

% to 0.2 wt.%, vanadium, 0.006 wt. boron a

Cast iron furthermore with molybdenum and / or 0.3 thick-walled castings can advantageously up to 1.0% l suppressed contain mass, nickel, exclusion of perlite.

0.3 to 2.0 wt.%, So that during quenching of cast iron the central suppression of the transcrystallization zone of porosity, which causes local

The advantage of such crystallization and fragility of the casting. There is also intensive heterogeneous nucleation of the primary structure in cast iron, which results in a refinement of the primary grain of the lamellar eutectic. In the cast state, the metal matrix consists

· The structure of austenite and the tough type of martensite, consisting of needles with a dislocation substructure. When cast iron is cooled slowly in sand form, martensite is dissolved after casting. The impact toughness value is 6-11 µm ^-2 and the hardness 46-53 HRC. The value of the relative abrasive wear resistance u of the cast iron according to the invention is 2.7 to 3.1. Another advantage is the longer service life of components and the possibility of wider use.

The cast iron according to the invention can also be hardened. After hardening to martensite and tempering to secondary hardness, the value of relative abrasive wear resistance can be increased to 3.3 to 4.0, hardness to 56 to 61 HRC and impact strength to 5.0 to 6.5 J.cm ^-2 '

DETAILED DESCRIPTION OF THE INVENTION

The invention is described in more detail by way of examples of a specific embodiment.

Example 1

The armor for crushers for crushing aggregates was made of cast iron with the following chemical composition:

[% w / w]

carbon C 2.60 manganese Mn 0.57 silicon Si 0.60 phosphorus P 0,028 sulfur WITH 0,021 chrome Cr 26.70 molybdenum Mo 0.50 nickel Ni 0.46 vanadium IN 0.10 zirconium Zr 0.02 boron <B 0.004 aluminium AI 0,038

The cast iron hardness of this chemical composition in the cast state was 50.5 HRC, the impact toughness 6.9 J.cm ^-2 , the relative abrasive wear resistance ψ = 2.9.

After heat treatment of 1,050 ° C, 1 h, oil, tempering 515 ° C, 5 h, air cooling, the hardness was 56 HRC, the impact toughness was 5.8 J.cm ^-2 and the relative abrasive wear resistance yf = 3.9 .

When grinding the aggregate, there is only a slight wear of the shredder armor.

Example 2

The armor of the aggregate crusher was made of cast iron having the following composition:

[% w / w]

carbon C 3.00 manganese Mn 0.67 silicon Si 0.37 phosphorus P 0,023 sulfur WITH 0,023 chrome Čr 24.60 vanadium IN 0.05 zirconium Zr 0.08 boron (B) 0.004 aluminium Al 0.015 molybdenum Mo 1.83 Mechanical Properties this

in Example 1.

cast irons were similar to

During the grinding of aggregates, the crusher armor wear occurs.

this cast iron only to a slight

Industrial applicability

The cast iron according to the invention finds intensive abrasive wear on the dynamically loaded machine.

especially in stone parts, exposed

Claims (2)

1. Abrasive wear resistant cast iron containing 1.8 to 3.5% by weight, carbon, 0.4 to 1.2% by weight, manganese, 0.3 to 0.8% by weight, silicon, 20 to 29% by weight, chromium 0.01 to 0.05 wt.%, Phosphorus, 0.01 to 0.03 wt. % containing from 0.05 to 0.2% by weight of vanadium, from 0.01 to 0.1% by weight of sulfur; zirconium, 0.002 to 0.006% by weight of boron and 0.01 to 0.1% by weight of aluminum. Cast iron according to claim 1, characterized in that it contains 0.3 to 2.0 wt.% Molybdenum and / or 0.3 to 1.0 wt.% Nickel.