RU2306353C1 - Cast iron - Google Patents

Abstract

FIELD: metallurgy; composition of cast iron for manufacture of parts subjected to friction and cutting tools.

SUBSTANCE: proposed cast iron contains the following components, mass-%: carbon, 3.56-3.61; silicon, 0.17-0.20; manganese, 0.25-0.28; phosphorus, 0.052-0.06; sulfur, 0.018-0.02; copper, 0.03-0.06; chromium, 1.45-1.52; nickel, 0.10-0.13; molybdenum, 0.80-0.93; titanium, 0.01-0.03; vanadium, 0.60-0.70; tungsten, 1.96-2.13; the remainder being iron.

EFFECT: enhanced wear resistance and ultimate breaking strength.

2 tbl, 1 ex

Description

The invention relates to metallurgy, in particular to the development of compositions of cast irons for the manufacture of parts operating in friction units, as well as cutting tools.

Known cast iron containing, wt.%: Carbon 2.50-3.50, silicon 1.70-2.60, manganese 0.64-1.80, sulfur 0.22-0.50, phosphorus 0.40- 1.0, antimony 0.005-0.08, copper 0.25-0.60, nickel 0.30-1.0, iron the rest (see AS No. 1673625, class C22C 37/08, publ. 08/30/91, Bull. No. 32).

Closest to the invention in technical essence and the achieved result is cast iron of the following chemical composition, wt.%: Carbon 3.65, silicon 1.77, manganese 0.56, phosphorus 0.16, sulfur 0.021, chromium 0.32, nickel 0 , 17, titanium 0.04, vanadium 0.05, the rest is iron (chemical composition according to GOST 1412-85).

A disadvantage of the known cast irons is - low density, hardness (wear resistance) and temporary tensile strength due to the content of increased volume fraction of graphite.

The objective of the invention is to reduce the volume fraction of graphite, increase the density and mechanical characteristics (hardness and temporary resistance) of cast iron.

This object is achieved in that cast iron containing carbon, silicon, manganese, sulfur, phosphorus, chromium, nickel, titanium, vanadium and iron, additionally contains tungsten, molybdenum and copper in the following ratio of components, wt.%:

carbon 3.56-3.61 silicon 0.17-0.20 manganese 0.25-0.28 phosphorus 0.052-0.06 sulfur 0.018-0.02 copper 0.03-0.06 chromium 1.45-1.52 nickel 0.10-0.13 molybdenum 0.80-0.93 titanium 0.01-0.03 vanadium 0.60-0.70 tungsten 1.96-2.13 iron - the rest.

The combined introduction of tungsten, molybdenum and copper into the cast iron in the indicated amounts with the stated ratio of all other components leads to dispersion of graphite precipitates, a sharp decrease in the volume fraction of graphite and a concomitant increase in the density of cast iron castings. During heat treatment, the presence of molybdenum and tungsten provides a significant increase in hardenability, an increase in mechanical properties due to the partial dissolution of graphite and a more complete martensitic transformation.

The introduction of tungsten, molybdenum and copper in amounts lower than the declared limits does not lead to the indicated effect of increasing the density and mechanical characteristics, and in quantities greater than the declared limits, to an increase in the cost of castings.

The proposed composition of cast iron with a specified ratio of all its constituent components ensures the achievement of a technical result consisting in a significant increase in wear resistance and temporary tensile strength of cast iron.

Obtaining this technical result is achieved by solving the problem at the inventive step, for example, the choice of alloying elements and their percentage ratio, which allows us to conclude that the proposed method meets the criterion of "inventive step".

Example. Iron was smelted in an electric arc furnace using standard charge materials and high-speed steel scrap. After melting and overheating of cast iron to 1500 ° C, the melt was subjected to thermal cycling.

The chemical composition and physico-mechanical properties of the proposed and known cast irons are shown in tables 1, 2.

The table shows that the cast iron of the proposed composition contains less graphite and has higher values of density, hardness, microhardness of perlite and temporary tensile strength.

The properties of cast iron were determined on samples not subjected to heat treatment.

The volume fraction of graphite was evaluated by the results of quantitative metallography on an EPIQUANT optical analyzer.

Density was determined on a WA-2000 analytical balance by hydrostatic weighing.

Hardness measurements were carried out on a TKS-1M hardness gage according to the Rockwell method with subsequent conversion of HRC units to HB.

To determine the microhardness of perlite, the PMT-3 device was used.

Mechanical tests of cylindrical samples were carried out according to the standard method on an IK-500 machine.

The use of the proposed cast iron for castings, for example knives for milling cutters, turning cutters and mills for processing wood and metal, can significantly reduce the cost of processed products.

Table 1 Cast iron The content of elements, wt.% FROM Si Mn R S Cu Cr Ni Mo Ti V W Fe one. 3.56 0.17 0.25 0,052 0.018 0,03 1.45 0.10 0.80 0.01 0.6 1.96 rest 2. 3.61 0.20 0.28 0.06 0.02 0.06 1,52 0.13 0.93 0,03 0.7 2.13 rest Famous 3.65 1.77 0.56 0.16 0,021 - 0.32 0.17 - 0.04 0.05 - rest

table 2 Cast iron Volume fraction of graphite,% ρ, kg / m ³ Hardness, HB Perlite microhardness, MPa σ _V , MPa one. 5 8013 555 3367 500 2. 3 8039 578 3566 550 Famous 20-21 7180 183-192 2183 195

Claims (1)

Cast iron containing carbon, silicon, manganese, sulfur, phosphorus, chromium, nickel, titanium, vanadium and iron, characterized in that it additionally contains tungsten, molybdenum and copper in the following ratio, wt.%: carbon 3.56-3.61 silicon 0.17-0.20 manganese 0.25-0.28 phosphorus 0.052-0.06 sulfur 0.018-0.02 copper 0.03-0.06 chromium 1.45-1.52 nickel 0.10-0.13 molybdenum 0.80-0.93 titanium 0.01-0.03 vanadium 0.60-0.70 tungsten 1.96-2.13 iron rest