CS204983B2 - Machineble nodular cast iron with resistance to wear and process for preparing thereof - Google Patents

Abstract

1448771 Nodular cast iron POLITECHNIKA SLASKA IM WINCENTEGO PSTROWSKIEGO 25 Jan 1974 [27 April 1973] 03458/74 Heading C7A A nodular cast iron of composition:- C 2.6 to 2.8% Si 4 to 4.5% Mn 0À1 to 0.2% Cr 0À15 to 0À25% S 0À03 to 0À06% P 0À05 to 0.08% Fe and impurities balance. The cast iron may contain spheroidal graphite and eutectic and hyper-eutectic alloy cementite in a silicon ferrite matrix and may be prepared from pig iron and ferro-alloys using an induction or arc furnace.

Description

The invention relates to well-machined and wear-resistant nodular cast iron and to a process for its manufacture.

The known nodular cast iron without alloying additives and unprocessed thermally have ferritic, ferriticoperletic, perletic and pearlitic-ledeburitic structure. Depending on the type of matrix, the nodular cast iron is wear resistant and has good tensile strength, which is characteristic of pearlitic cast iron, or has high wear resistance, high hardness and brittleness, characteristic of cast iron with a pearlitic-ledeburistic structure.

The use of cast iron with a ledeburistic structure is limited in industrial practice due to the high brittleness and hardness of the material, which results in cast iron of this type being difficult to process. The limitations of these materials lead to wear-resistant ledeburitic cast irons being replaced by more expensive but more ductile non-ferrous metal alloys and alloy steels.

The purpose of the invention is to obtain a modular cast iron of the new type, which has high wear resistance and at the same time is easy to machine.

These disadvantages are overcome by the machinable, wear-resistant nodular cast iron, which according to the invention contains 2.6 to 2.8 wt.

% carbon, 4.0 to 4.5 wt.% silicon, 0.1 to 0.2 wt. % Manganese, 0.15 to 0.25 wt. % of chromium, 0.03 to 0.06 wt. % sulfur, 0.05-0.08 wt. % Of phosphorus and has a structure consisting of a metallic matrix in the form of silicon, ferrite, precipitated spheroidal graphite and carbon bonded in the form of eutectic and nadeutectic cementite, the structure comprising traces of up to 3% by weight of perlite.

Nodular cast iron is produced by melting the batch, spheroidizing and adding -ferosilicon; the process according to the invention is characterized in that the metal charge consisting of low-manganese pig iron, steel and iron scrap, ferro-silicon and ferro-chromium is melted to induction heating at a temperature of up to 1500 ° C to a melt containing 2.7 to -2, 9 wt. % carbon, 2.4 to 2.9 wt.% silicon, 0.1 to 0.2 wt. % manganese, 0.1-0.2 wt.%, chromium percent, 0.07 wt. % sulfur and 0.06 wt. % of the phosphorus in which the spheroidization increases the silicon content to 4.0 to 4.5 wt. % magnesium and added in an amount of 2.5 to 3.0 wt. %, based on the weight of the melt, and after spheroidization, ferro-chromium containing -60 wt. % chromium to increase the chromium content in the melt to 0.15 to 0.25 wt.%.

The cast iron according to the invention has increased wear resistance while maintaining good strength properties. The characteristic of cast iron according to. the invention has good plasticity which allows the intermeshing surfaces of the cooperating cast iron components to match each other; this property also has the advantage that the cast iron according to the invention can be machined very well.

The cast iron according to the invention is cast directly into the casting molds without additional heat treatment and without any expensive alloying additives.

Example 1

Metal charge per tonne of cast iron: low manganese pig iron

4.3 wt. % carbon, 0.17 wt. % silicon, 0.005 wt. % manganese,

0.01 wt. % chromium - Θ0Ο kg steel waste with weight content % carbon, 0.5 wt.% silicon, 0.7 wt. % 'manganese,

0.07 wt% sulfur, 0.06 wt% phosphorus - 200 kg iron · scrap containing

2.8 wt. % carbon; 4.0 wt. % Silicon, 0.2 wt.% Manganese, 0.07 wt. % sulfur, 0.06 wt.% phosphorus - 100 kg foresilicon with a wt% silicon content - 30 kg ferochrome - with a wt. % chromium - 3.5 kg

Melting in an induction furnace

Composition after melting: 2.7 to 2.9% by weight. % carbon, 2.4 to 2.9 wt.% silicon, 0.1 to 0.2 wt.% manganese, 0.1 to 0.2 wt. % chromium, 0.8 wt. % sulfur, 0.06 wt. % phosphorus.

Spheroidization temperature - 1460 ° C

The amount of FeSiMg master alloy containing 45 wt. % silicon 8% magnesium - 30 kg

Ingredients to be added to the ladle after spheroidising:

ferrochromium containing

60 · wt. % chromium - 1.5 kg of ferro-silicon containing ° / o silicon - 1.5 · kg

Example 2

Example 3

Charge: low pig iron

manganese-containing steel scrap iron ferro-silicon ferochrome 600 kg 150 kg 150 kg 27 kg 3,5 kg 600 · kg 100 kg 200 kg 24 kg 3,5 kg melting in an induction furnace composition after melting 2.8 wt. % C 2.9 wt. % C 2.7 wt. ° / o Si 2.7 wt. ° / o Si 0.15 wt. % Qty 0.15 wt. % Qty 0.20 wt. % Cr 0.20 wt. % Cr 0.08 wt. % S max. 0.08 wt. % S · max. 0.06 wt. ·% P max. 0.06 wt. % P max. spheroidization temperature 1480 ° C 1480 ° C amount of pre-reinforcing FeSiMg 30 kg 30 kg Ingredients: ferochrom 1.5 kg 1,5 -kg ferrosilicium 1.5 kg 1.5 kg

Claims (2)

OBJECT OF INVENTION Wear resistant nodular cast iron, characterized in that it contains 2.6 to 2.8 wt. % of carbon, 4.0 to 4.5% by weight of silicon, 0.1 to 0.2% by weight of manganese, 0.15 to 0.25% by weight of chromium, 0.03 to 0.06. % by weight of sulfur, 0.05 to 0.08% by weight of phosphorus and has a structure consisting of a metallic matrix in the form of silicon ferrite, precipitated spheroidal graphite and carbon bonded in the form of eutectic. and nadeutectic cementite, wherein the structure contains traces of up to 3% by weight of perlite. 2. A process for the production of an alloy according to claim 1 by melting the batch, spheroidization and addition of ferro-silicon, characterized in that the metal batch consisting of low manganese content, steel and iron scrap, ferro-silicon and ferochrome with induction heating at a temperature of up to 1500 ° C melts to a melt containing 2.7 to 2.9 weight percent carbon, 2.4 to 2.9 weight percent silicon, 0.1 to 0.2 weight percent manganese, 0.1 to 0.2 weight percent % of chromium, 0.07% by weight of sulfur, and 0.06% by weight of phosphorus, in which the silicon content is increased to 4.0 to 4.5% by weight with the addition of molten ferro-silicon alloy containing 45% w / w silicon during spherodization; % by weight of magnesium and added in an amount of 2.5 to 3.0% by weight based on the weight of the melt, and after spheroidization, ferrochrome containing 00% by weight of chromium is added to the batch to increase the chromium content in the melt to 0.15 to 0.25% by weight.