SU1719452A1 - Aluminum base casting alloy - Google Patents

Abstract

The invention relates to aluminum-based casting alloys used to produce thick-walled parts. working at elevated temperatures and experiencing shock and vibration loads. The aim of the invention is to increase the mechanical properties, reduce linear shrinkage and porosity, which is achieved by the additional content of titanium nitride in the alloy. Foundry alloy based on aluminum contains, wt%: silicon 3.5-6.0; magnesium 0.3-0.6; zirconium 0.01-0.05; titanium nitride 0.01-0.02; aluminum else. The alloy has the following properties: tensile strength of 224-232 MPa; relative lengthening of 3-3,2%; linear shrinkage of 0.8%. Porosity 1 point. 2, tab.

Description

The invention relates to non-ferrous metallurgy and can be used to produce thick-walled parts operating at elevated temperatures and experiencing shock and vibration loads.

Known alloy based on aluminum, containing silicon and magnesium, wt;%: SI 6.0-8.0; Md 0.2-0.4; AI the rest.

However, the alloy has low mechanical properties and cannot be used to obtain critical parts.

Doping alloys containing nitrogen are known.

However, these alloys are expensive and complex, since they contain Cu, Co, N1, Y, Cr, V, TI, 2m. The effect of increasing the mechanical properties is achieved by the formation (or insertion) of endogenous particles of aluminum nitrides and other alloying elements into them. However, the endogenous nitride particles do not possess all the signs of a good modifier.

Closest to the proposed alloy is A356 of the following composition, wt.%:

Md 0.3-0.6

SI 3.5-6.0

C 0,1

Fe 0.6

MP 0.5

,eleven

Pb 0.1

Sn 0.05

Ti 0,2

AI Else

 - impurities.

Yu

ate

Yu

However, the known alloy has a complex chemical composition and cannot be used to produce thick-walled castings due to their low crack resistance.

The purpose of the invention is to improve the mechanical properties, reducing linear shrinkage and porosity.

The goal is achieved by the fact that the known aluminum-based alloy additionally contains titanium nitride in the following ratio, wt.%:

Silicon3.5-6.0

Magnesium013-0,6

Zirconium 0.01-0.05

Titanium Nitride 0,01-0,02

Titanium nitride is obtained in the form of a powder by plasma-chemical synthesis.

The proposed alloy is obtained as follows.

In the electric furnace of the type of SSGOL-1.1.6.12-MZ-U4.2, the silo brand silumin melted. The melt was overheated to 1000 K and A8 aluminum was introduced. Then, at the same temperature of 1000 K, Mg90 brand magnesium was introduced. The titanium nitride was introduced into the melt together with the addition of zirconi from potassium fluorocirconate.

Samples for determining mechanical properties were obtained by cutting out castings from the body. The temporary tensile strength was determined on an FP 100/1 tensile testing machine, the hardness was determined on a BriJel press of the TSH type - 2M by indentation of a ball

(GOST 9012-59). The micro- and microstructures were studied using an NEOFOT-2 optical microscope.

The chemical composition of the samples is given in table. one.

The test results are shown in Table. 2

The proposed alloy has improved mechanical properties compared with the prototype and is characterized by low shrinkage and porosity. Possible application of the alloy - casting thick-walled and differential castings.

Claims (1)

Invention Formula Aluminum-based foundry alloys containing: silicon, magnesium and zirconium, characterized in that. that in order to improve mechanical properties, reduce linear shrinkage and porosity, it additionally contains titanium nitride in the following ratio of components, wt.%: Silicon3.5-6.0 Magnesium0.3-0.6 Zirconium 0.01-0.05 Titanium Nitride 0.01-0.02 Aluminum Else Table 1 table 2