UA66198A - A high-strength casting aluminium alloy - Google Patents

Abstract

An alloy based on aluminium contains copper, manganese, titanium, silicon, cadmium. The alloy additionally contains carbon and nitrogen.

Description

The invention belongs to the field of non-ferrous metallurgy and can be used as a material for the manufacture of structures, or their elements, parts of machines and mechanisms.

Known alloy of the same purpose AMA, 5Kd (see DSTU - 2839-94, Cast aluminum alloys, - 1995, - Z4sb.), which contains (in mass. 90):

Copper 4.3-4.995

Manganese 0.35-0.69 o

Titanium 0.05-0.3596

Cadmium 0.1-0.2596

Silicon up to 0.05905

Magnesium to 0.0395.

The disadvantage of this alloy is a low level of technological properties, namely, a tendency to the formation of hot and cold cracks during pouring and a decrease in the level of mechanical properties, which is especially evident when casting into metal molds or when casting thin-walled products.

An alloy was adopted as a prototype (see Zolotorevsky V.S. Structure and strength of aluminum alloys M.

Metallurgy,-1981.-190 p.), which contains:

Copper 4.3 - 4995

Manganese 0.35 - 0.690

Titanium 0.05 - 0.359

Cadmium 0.1 -0.2596

Zirconium 0.05 - 0.396

Silicon up to 0.05905

Magnesium to 0.0395.

The disadvantage of this alloy is a low level of technological properties, namely, a tendency to the formation of hot and cold cracks during casting and a decrease in the level of mechanical properties and their instability, which is especially evident when casting into metal molds or when casting thin-walled products, as well as the fact that the introduction of zirconium significantly increases the cost of the alloy. The high propensity of this alloy to the formation of hot and cold cracks, a decrease in the level of mechanical properties and their instability, especially when casting in metal molds, is associated with a high chemical affinity between zirconium and copper. As a result, zirconium with copper forms intermetallics containing zirconium and copper, which, under the conditions of accelerated cooling of the melt, do not have time to dissolve during peritectic reactions, as a result of which the content of copper and zirconium in the solid solution decreases, which causes a decrease in the level of mechanical properties of the alloy and their instability.

The basis of this invention is the task of increasing the level of technological and mechanical properties of the alloy when casting the latter into metal molds, by introducing into its composition carbon in the concentration range from 0.001 to 0.035 by mass, and nitrogen 0.003-0.01 by mass, which ensures obtaining complex according to the shape of castings from high-strength AM4A, 5Kd alloy without hot and cold cracks, when casting castings in metal molds with stable mechanical properties at the level of DSTU 2839-94.

The task is accomplished by the fact that in an alloy based on aluminum containing copper, manganese, titanium, silicon, cadmium, the new thing is that it additionally contains carbon and nitrogen, with the following ratio of components, mass 905:

Copper 4.2-5.5

Manganese 0.35-0.8

Titanium 0.05-0.5

Silicon 0.03-0.15

Cadmium 0.1-0.25

Carbon 0.001-0.035

Nitrogen 0.003-0.01

Aluminum is different.

The introduction of carbon in the range from 0.001 to 0.035 by mass, and nitrogen 0.003-0.0195 by mass ensures an increase in the number of active growth centers of E - solid solution, due to the formation of stable nucleation phases in the melt of an alloy of the TiS, TIM, TAS, TIAIM type and metastable cluster of groups containing carbon, nitrogen, titanium and aluminum changes the nature of the interaction of components in the melt due to macroalloying with carbon and nitrogen. This leads to the destruction of interatomic bonds between titanium and copper in the melt and the formation of bonds between titanium, carbon, nitrogen and aluminum. As a result of the change in the nature of the interaction of the alloying components in the melt, it approaches the solid, which is manifested in a decrease in temperature fluctuations during the cooling and heating of the melt, solidification and melting of the solid solution, and the formation of a homogeneous, fine, equiaxed structure of the cellular-dendritic type without inclusions of coarse intermetallic phases of insoluble during heat treatment. As a result of the formation of a fine equiaxed structure, the casting has the ability to compensate for shrinkage stresses due to the liquid phase, which separates the crystals and feeds the casting from the overpour, as a result of which conditions are created for obtaining complex-shaped castings from a high-strength alloy without hot and cold cracks, when casting castings in metal forms with stable mechanical properties at the level of DSTU 2839-94.

The effect of carbon and nitrogen microalloying on the technological and mechanical properties of the proposed alloy is presented in the table.

Example of implementation: melting of the alloy was carried out in a resistance furnace, in a graphite chamotte crucible. AMA4.5Kd alloy (see DSTU 2839 - 94) of the following composition was used as the initial charge:

Copper 4,590

Manganese 0.6

Titanium 0.229

Cadmium 01596

Silicon 0.056

Magnesium 0.039

After melting the alloy, a ligature containing carbon, nitrogen and titanium was introduced into it. After the introduction of the ligature, the melt was mixed with a graphite stirrer, held for 5 minutes in the temperature range of 700-740"С and poured onto standard (according to DSTU 1583-89) samples for mechanical tensile tests. Melting of samples for mechanical tests was carried out in a heated to a temperature of 200"С standard metal form, the diameter of the working part of the samples is 12 mm.

Heat treatment of alloys was carried out in a resistance furnace, in which an atmosphere stirrer is installed.

Mechanical properties were determined on samples cast in a mold in accordance with the requirements of DSTU 1583-89.

Tests of mechanical properties were carried out on a TIVA - TE5T tearing machine according to standard methods.

The amount of carbon and nitrogen in the composition of the alloy was determined using vacuum spectral analysis.

As can be seen from the data presented in the table, the test results given in examples 2, 3, 4 achieve a higher level of technological (reduced tendency to crack) and mechanical (tensile strength, hardness, relative elongation) properties than in examples 1, 5. In the prototype and in the alloys that are in the range of the claimed alloy, the technological and mechanical properties are at a lower level.

This confirms the provision of obtaining complex-shaped castings from the high-strength alloy AMA, 5Kd without hot and cold cracks, pouring of castings into metal molds with stable mechanical properties at the level of DSTU 2839-94.

This alloy can be used for the manufacture of structures, or their elements, parts of machines and mechanisms, namely aircraft and rocket bodies on an industrial scale.

Table

Chemical composition, Outside Outside mech properties are declared declared

MP 777777 | 03506 | sh 02 | 02 | 038 | 045 | 05 | 08 | 170 li 77777777 1005005, 2 yushkyu004 2 | 01 | 025 | 0th | 03 | 05 | 06 Kf(|/ vi | 09030005 6 yush 006 | 006 | 005 | 004 | 0045 | 003 | 008 r is 77777717 - 117 ,1po009 | bot | 0015 | 002 | 0025 | 0035 | 004 mm 777777771 - 170771 - 17077170771 0007 | 0008 | 0009 | 001 | 0012

Strength limit, at

He after heat treatment (T5)

relative

With IZ after heat treatment (T5) (Hardness of NAV | 48-56 | 55 | 68 | 79 | 85 | 80 | 73 | 63 (cast samples for mechanical 20 15 Kk) 4 12 tests cast in a metal mold

Claims (1)

Aluminum-based alloy, which contains copper, manganese, titanium, silicon, cadmium, which is distinguished by the fact that it additionally contains carbon and nitrogen at the following ratio of components, mass 9o: copper 4.2 - 5.5 manganese 0.35 - 0.8 titanium 0.05-0.5 silicon 0.03-0.15 cadmium 0.1 - 0.25 carbon 0.001 - 0.035 nitrogen 0.003 - 0.01 aluminum the rest.