GB2157315A - Aluminium bronze alloy containing silicon - Google Patents

Abstract

An aluminium bronze alloy contains NOTGREATER 0.15% Mn and 0.5 to 2.5% of Si to improve its characteristics when hot and cold. The preferred composition consists of, in wt %. Al 8.5-10.5 Ni 12 -20 Zn 8.5-10.5 Fe 0 - 1 Mn 0 - 0.15 Si 0.5- 2.5 P + Sn + S + Pb 0 - 0.03 Cu balance R

Description

SPECIFICATION Aluminum and silicon multi-compound bronze alloy BACKGROUND OF THE INVENTION It is a well-known fact that most of the total production of metals is used in industry in the form of alloys for the purpose of modifying some of the properties of the constituent metals enhancing certain characteristics and correcting defects in them.

An important category of alloys is that of the aluminum multi-compound bronzes.

A characteristic of these alloys is the presence of Mn to improve their properties, especially their malleability. One type of alloy is already on sale under the name of Nialloy 2510, also created by the inventor of this present disclosure, and although it contains a low percentage of Mn, it possesses high characteristics of resistance to mechanical stresses and to corrosion, its composition being: Ni 14-16% Al 8.5-10.5% Zn 9.5-10.5% Fe maximum 1 Mn 0. 15% P + Sn + S + Pb maximum 7.7% Cu remainder Mechanical characteristics when in the form of a rough casting may be considered as being the following: Strength 608 N/mm2 Elastic limit 265 N/mm2 Stretch 11% Brinell hardness 160 HB The principal property of this alloyis that it can be hot-pressed in pieces even exceeding one kilo in weight.The above invention greatly improves the characteristics of such alloys as will now be explained below.

SUMMARY OF THE INVENTION Subject of this invention is a quaternary alloy, multicompound of aluminum bronze which, in addition to the absence of Mn, or to a very large reduction in its percentage, possesses a percentage of Si from 0.5 to 2.5. Percentages of the other consitituents remain practically the same as in the Nialloy 2510 alloy, referred to above, except for the P + Sn + S + Pb impurities which, in the above invention, are greatly reduced to a maximum of 0.03%.

Composition of said alloy is as follows: Ni 12-20% Al 8.5-10.5% Zn 8.5-10.5% Fe maximum 1% Mn maximum 0. 15% Si 0.5-2.5% P + Sn + S + Pb maximum 0.03% Cu remainder The presence of Si has made a very great improvement to both the hot and cold mechanical characteristics as shown by the following details of values found during testing.

Strength 686 N/mm2 Elastic limit 520 N/mm2 Stretch 5% Brinell hardness 190 HB This alloy has proved to be particularly sensitive to heat treatments such as annealing, normalizing, hyper-hardening and others, that make it suitable for a very wide range of uses.

The percentages of improvement, indicated for the alloy in the form of a rough casting, also occur in the various characteristics that the alloy acquires subsequently to the different hot and cold treatments such as forging, pressing, extrusion, lamination, drawing, hobbing, coinage.

This is exemplified in the considerable increase obtained in hardness or toughness.

For example, by executing full annealing up to 900"C a reduction can be obtained in strength and in the elastic limit of 30% together with an increase of 100% in stretch.

The positive effect of the presence of Si is clearly seen in the equilibrium diagram.

The limits between the "alpha" phase and the "alpha + gamma" phase (corresponding to the start of the fragile compounds beyond the eutectoid) are moved towards the "alpha" phase thus greatly reducing fragility.

When the alloy, subject of this invention, is subjected to a treatment of pendular annealing, the range of its mechanical properties are considerably increased.

These may be summed up as follows: Improvement in the characteristics when hot, Greater resistance to wear both when hot and when cold, Greater resistance to viscous flow, Stainless both when hot and when cold, Lower density and therefore lower specific gravity, Less thermal expansion, Greater sensitivity to annealing, normalizing, hyper-hardening, Better mechanical characteristics both hot and cold, Maintenance of mechanical characteristics up to 400'C, Possibility of using up to 850"C, Higher elastic limit even as much as 95% more, Highly polishable, High resistance to heat and cold, to erosion, to cavitation, High resistance to corrosion, to salt water, to acids, The structure is particularly stable thus avoiding crystalization and becoming fragile under alternating stresses and under repeated blows, Suitability for hot-pressing, Particular suitability for use in the chemical, glass, food and mining industries, in ship building, and especially in the manufacture of gearings, gears, leading screws, worm screws, parts for superheated steam, sliding blocks, ships' propellors sliding bearings, crankshafts, articulated joints, dies.

As the applications of the invention have been described as examples only and not limited to these, it is understood that any equivalent application of the inventive concepts explained and any product executed and/or in operation in accordance with the characteristics of the invention, will be considered as included within its field of protection.

Claims (7)

1. A multi-compound aluminum bronze alloy characterized by the presence of a considerable quantity of Si, comprised between the values of 0.5 and 2.5%, by the absence of Mn or by a great reduction of Mn which does not exceed the value of 0. 16% remaining at that of an inclusion and not of an alloying element while the impurities P + Sn + S + Pb reach a maximum value of 0.03%, all the above improving its hot and cold properties, its resistance to wear and its viscous flow.

2. A multi-compound aluminum bronze alloy as in Claim 1 characterized by the fact that in the equilibrium diagram the limit between the alpha phase and the alpha + gamma phase is moved towards the alpha phase thus reducing fragility.

3. A multi-compound aluminum bronze alloy as in Claim 1 characterized in that by heat treatments such as annealing, normalizing, hyperhardening and others as well, it has shown itself to be suitable for a wide variety of uses and especially to those in the chemical, glass, food and mining industries, in ship building and particularly in the manufacture of gearing, leading screws, worm screws, parts for superheated steam, sliding blocks, ships' propellors, sliding bearings, crankshafts, articulated joints, dies and very many other parts as well.

4. A multi-compound aluminum bronze alloy as in Claim 1 characterized by the following preferred composition: Ni 12-20% Al 8.5-10.5% Zn 8.5-10.5% Fe maximum 1% Mn maximum 0. 15% Si 0.5-2.5% P + Sn + S + Pb maximum 0.03% Cu remainder its values when in the state of a rough casting being considerably better than those of known alloys, approximately as follows: Strength 686 N/mm2 Elastic limit 520 N/mm2 Stretch 5% Brinell Hardness HB 190 and, following the various treatments and transformations, possessing greater hardness and toughness.

5. A multi-compound aluminum bronze alloy as in Claim 1, characterized in that, by means of a pendular annealing treatment, the range of its mechanical properties increases considerably.

6. An aluminium bronze alloy comprising 0.5% to 2.5% silicon and less than 0. 16% manganese.

7. An aluminium bronze alloy substantially as herein described.