RU1786172C - Wear-resistant cast iron for deep drawing - Google Patents

Abstract

The invention relates to metallurgy, in particular to the search for cast iron for deep drawing dies. SUMMARY OF THE INVENTION: Cast iron contains elements in the following ratio, wt.%: Carbon 3.1-3.3; silicon 3.2-3.9; manganese 0.3-0.8; chrome 3.0-3.6; copper 1.8-2.1; nickel 1.1-1.9; aluminum 0.3-0.4; vanadium 0.5-0.7; iron - the rest, with the ratio of the sum of carbide-forming elements V + Cr to the sum of alloying elements of the matrix Ni + Cu + Mn + Si 0.40-0.67. A change in the quantitative ratio of C, Cr, Cu, AI, V makes it possible to increase the wear resistance and reduce the tearing ability of the die material. 2 tab.

Description

ate

WITH

The invention relates to metallurgy, in particular to the search for cast iron for deep drawing dies.

Known cast iron 1 containing the following components, wt.%:

Carbon 3.65-4.5 Silicon 0.8-3.0 Manganese 0.5-2.0 Chromium 0.2-1.1 Vanadium 0.25-0.5 Titanium 0.3-1.1 Iron Other Remnant Known cast iron has low wear resistance when used for dies.

The closest technical solution to the proposed one is wear-resistant cast iron of 2 composition, wt.%: Carbon 2.6-2.9 Silicon 3.2-3.9 Manganese 0.3-0.8 Chromium 1.5-2.2

Copper

Nickel

Calcium

Aluminum

Vanadium

Iron

0.5g1.5

0.01-0.6

0.01-0.08

0.04-0.2

0.04-0.4

Rest

The disadvantage of this cast iron is its increased seizure when using cast iron for deep drawing dies. The purpose of the invention is to increase the wear resistance and scuffability of cast iron.

This goal is achieved in that the cast iron, including carbon, silicon, manganese, chromium, nickel, copper, aluminum, vanadium and iron, contains components in the following proportions, wt.%:

Carbon 3.1-3.3 Silicon 3.2-3.9 Manganese 0.3-0.8 Chromium 3.0-3.6 Nickel 1.8-2.1 Copper 1.1-1.9

Vj 00

about

and

Vj

Nd

Aluminum 0.3-0.4 Vanadium 0.5-0.7 Iron else As an impurity, cast iron may contain sulfur in an amount of up to 0.03 wt.% And phosphorus up to 0.15 wt.%.

Comparative analysis with the prototype allows us to conclude that the claimed composition of cast iron differs mainly from the known ratio

.... L ,.), g. s- 0.40 ... 0.67. Thus, (Ni + Cu + Mn + Si)

At the same time, the claimed technical solution meets the criterion of novelty. Analysis of the known compositions of cast irons 1,2 showed that the substances introduced into the cast iron are known. However, their combination did not provide the required material properties for the stamp, which they exhibit in the claimed solution, namely, a combination of durability and scoring resistance. Thus, this composition gives cast iron new properties, which allows us to conclude that the claimed solution meets the criterion of significant differences. The proposed ratio (m- r lb} ryrv- 0-40 ... 0.67 (Ni + Cu 4- Mn + Si)

expresses the necessary fraction of carbide inclusions of the B alloyed matrix to give cast iron the necessary properties. When the ratio is lower than 0.4, the material has low hardness, low wear resistance, which leads to adhesion of the stamped material. This is due to an insufficient solid carbide content.

When the ratio is higher than 0.67, the cast iron is poorly machined, with increasing tearing ™, the limits for the content of components are selected for the following reasons.

The amount of carbon is selected in such a way as to provide the necessary degree of eutecticity. With a decrease in carbon content of less than 3.1 wt.%, The amount of carbides decreases, which leads to a decrease in wear resistance. An increase in carbon content above 3.3 wt.% Converts the alloy into hypereutectic, coarse inclusions of graphite appear, violating the uniformity of the alloy, which leads to the appearance of scoring during stamping.

The presence of chromium in the amount of 3.0 wt.% Is not sufficient to form the required amount of special chromium carbide. With an increase in the chromium content of more than 3.0 wt.%, The wear resistance and the resistance to scoring of cast iron sharply increase. However, when

a chromium content of more than 3.6 wt.% deteriorates mechanical workability.

The presence of silicon in cast iron is a prerequisite for

adjust the content of special chromium carbide in cast iron. Reduced Si content below 3.2 May. % increases bleaching, decreases the amount of graphite, coarse carbide inclusions appear, and slower resistance decreases. When introduced into the Si alloy above 3.9 wt.%, Cast iron becomes hypereutectic, which leads to the same consequences as an increase in carbon above a predetermined value.

5 The amount of manganese is determined by smelting technology. The lower limit is determined by its minimum content necessary for the binding of sulfur to manganese sulfides. It is recommended that the Mn content not be increased by more than 0.8 wt.%, Since the amount of residual austenite increases significantly, which leads to the buildup of the material being stamped and a decrease in scoring resistance.

5Copper is introduced into the alloy as an element increasing the heat resistance of the alloy. When the Cu content is below 1.8 wt.%, There is no effect on the increase in scoring resistance, since at this ratio

At the silicon content and the sum of nickel and chromium, no release of copper in the form of free inclusions is observed. A copper content above 2.1% by weight is not economically feasible since the resistance to scoring does not increase5.

Nickel is introduced into the alloy as an austenitizer and an alloying matrix element. When the amount of Ni is below 1.1 May. % hardness and wear resistance noticeably reduced

0 cast iron during hardening of large dies due to a decrease in the stability of austenite. An increase in the Ni content above 1.9 wt.% Leads to the appearance of areas of residual austenite, which lowers the scoring resistance.

5Aluminium is introduced into cast iron as a deoxidizer and has a refining and graphitizing effect. The decrease in aluminum content below 0.3 wt.% Leads to the fact that instead of chromium carbides

Separate cementite inclusions appear in thin sections of the casting, which lowers the scoring resistance. An increase in aluminum content of more than 0.4% is impractical, which leads to the formation of

5 captives, increasing the marriage of castings. An increase in the aluminum content to 0.4 wt.% Will make it possible to achieve a positive graphitizing and modifying effect without calcium additives and to maintain the necessary set of physicochemical properties.

At the same time, the removal of calcium iron from the composition simplifies the process and provides an increase in the efficiency of cast iron.

Vanadium is introduced into the composition of cast iron as a carbide forming element. With a decrease in its content below 0.5%, ledeburite colonies appear, since vanadium reduces the critical chromium content necessary to replace ledeburite with chromic eutectic, which reduces burr resistance. An increase in vanadium of more than a given value leads to the appearance of coarse carbide inclusions, which reduce the scoring resistance.

Cast iron was smelted by known technology in an induction furnace LPZ-67 and five samples of each heat were cast. As charge materials, pig iron, steel scrap and ferroalloys were used. After annealing and quenching (heat treatment modes are shown in Fig. 1), the following mechanical tests were carried out.

The antifriction properties — wear resistance (I) and scoring resistance (P) were determined according to the well-known methodology of the Central Research Institute of MPS on an MTV-1 friction machine with reciprocating motion and liquid lubrication (M14B oil according to TU 38-101-421-73). Wear resistance was determined by the loss of weight of the sample in mg per 100 hours of operation of the machine, and resistance to scoring was determined by the value of specific pressure causing damage to the friction surfaces of the samples, a sharp increase in the coefficient of friction and an increase in the contact temperature.

Cast iron machinability was evaluated using a machinability index representing the ratio of the maximum cutting speed causing fracture of a VK M alloy cutter during turning

within 1 h, of a cast-iron sample with a cutting depth of 1.5 mm and a feed rate of 0.5 mm / rev (for the alloys under study, to the maximum cutting speed of known cast iron).

The chemical composition of the known and proposed compositions of cast iron and their properties are given in tables 1 and 2.

Analysis of the obtained data indicates that an increase in the content of carbon, chromium, copper, nickel, aluminum and a change in their ratio leads to an increase in wear resistance and an increase in tear resistance. The proposed improved composition of cast iron will provide an increase in the service life of deep-drawn dies by 1.5 times. The expected economic effect under the conditions of tractor production will be 42.0 thousand rubles. in year.

Claims (1)

SUMMARY OF THE INVENTION Wear-resistant cast iron for deep-drawn dies, containing carbon, silicon, manganese, chromium, nickel, copper, aluminum, vanadium and iron, characterized in that, in order to increase wear resistance and reduce seizure, it contains elements in the following ratio, wt. .%: Carbon 3.1-3.8 Silicon 3.2-3.9 Manganese 0.3-0.8 Chrome 3.0-3.6 Copper 1.8-2.1 Nickel 1.1-1.9 Aluminum 0.3-0.4 Vanadium 0.5-0.7 Iron-steel with a ratio of the sum of carbide-forming elements Cr, V to the sum of alloying elements of the matrix Ni, Cu, Mn, Si - 0.40 ... 0.67. Table 1 table 2