Physicochemical preparation of the AlSi11 alloy for ... · bFoundry Co - operative in Ustron, 43 - 450 Ustroń, 9 Harbutowicka St., Poland *Corresponding author. E-mail address: [email protected]

A R C H I V E S

o f

F O U N D R Y E N G I N E E R I N G

Published quarterly as the organ of the Foundry Commission of the Polish Academy of Sciences

ISSN (1897-3310) Volume 10

Issue 2/2010

33 – 38

6/2

A R C H I V E S o f F O U N D R Y E N G I N E E R I N G V o l u m e 1 0 , I s s u e 2 / 2 0 1 0 , 3 3 - 3 8 33

Physicochemical preparation of the AlSi11

alloy for castings of fire-fighting equipment

M. Dudyka,*, T. Ciućka

a, J. Pietor

b, S. Płonka

a

aUniversity of Bielsko - Biała, Department of Manufacturing Technology and Automation,

43 - 309 Bielsko-Biała, 2 Willowa St., Poland bFoundry Co - operative in Ustron, 43 - 450 Ustroń, 9 Harbutowicka St., Poland

*Corresponding author. E-mail address: [email protected]

Received 15.03.2010; accepted in revised form 10.05.2010

Abstract

The paper presents results of reaction kinetics investigation of crystallization processes of refined, modified with Sr and Sb as well

as filtered silumin destined to casting of fire-fighting equipment. It has been determined an effect of performed upgrading processes

of: refining, modification and filtering on changes of mechanical properties (Rm, A5, HB and KCV) of the AlSi11 (AK11) alloy. There

were performed metallographic examinations of the upgraded alloys and flooded foamed filters. It has been proved, that developed and set

into production upgrading technology of the AlSi11 (AK11) alloy enables casting of fire-fighting equipment, complying with rquirements

of the European Union.

Keywords: Aluminum Fire-Fighting Equipment, Silumis, Refining, Modification, Filtering

1. Introduction

High mechanical, technological and operational requirements

imposed by domestic and foreign recipients of aluminum castings

destined for fire-fighting equipment have forced producers of

these alloys to introduce a modern manufacturing technologies.

Castings for fire-fighting equipment produced from aluminum

alloys should be characterized with a suitable:

High mechanical properties ( Rm, A5, HB and KCV).

Tightness with respect to flowing media.

Roughness.

Easiness and reliability of connection with other fire-

fighting equipment components.

Manufactured up-to-now from domestic charge materials (pig

sows) aluminum castings of fire - fighting equipment not fully

comply with requirements of national and EN standards.

It concerns mainly a castings poured into permanent moulds and

pressure casting dies.

Within Polish foundry industry are commonly used, during

melting, a suitable metallurgic processes aimed at obtaining of

a predetermined properties, demanded by national and foreign

standards [1, 2].

Pig sows used to production of reliable castings, where

metallic charge materials containing aluminum scrap have been

used, require implementation of refining and modification

processes of liquid metal.

To enable possibly maximal purification of the alloy from

oxides and non-metallic inclusions, prior casting into mould one

should perform processes of filtration [6].

Mentioned above upgrading processes of aluminum alloys

were implemented during melting of the AlSi11 (AK11) alloy

destined to production of reliable castings for fire-fighting

equipment.

mailto:[email protected]


2. Methodology and results of the tests

Production of aluminum castings destined to fire-fighting

equipment, according to requirements of the PN - EN 1706 (2001)

standard, is presented on example of permanent-mould castings

of a suction sleeve coupler according to the PN-91/M-51031

standard, and fire hydrant attachment according to the PN-91/M-

51038 standard, produced from the EN AC-44000, AlSi11

(AK11) alloy.

Shape and appearance of the fire-fighting equipment’s

castings are shown in the Fig 1.

a)

b)

Fig. 1. View of the fire - fighting equipment: a – raw casting

of fire hydrant attachment, b – suction sleeve coupler, ø75

Permanent-mould castings of aluminum fire-fighting

equipment poured directly after melting of the pig sows from

AlSi11 (AK11) alloy not fully comply with requirements imposed

by the PN-91/M-51031 standard, i.e. strength and tightness of the

castings most of all.

To obtain higher mechanical properties, comparing with the

actual ones, after melting of the pig sows one performed suitable

upgrading processes of the AlSi11 (AK11) alloy. For this

purpose, after melting of the pig sows from the investigated alloy

in electric resistance furnace, one performed refining with use

of “Alraf ”preparation.

Liquid alloy, refined in two separate electric furnaces

underwent the modification: with AlSiSr10 master alloy

or metallic antimony.

Using the alloys upgraded in such way, one poured a test

samples to mechanical, metallographic and chemical analysis

tests, with and without filtration process during their pouring [6].

Moreover, in order to have confirmation of correctness of the

performed metallurgical processes, one investigated a course

of kinetics of the crystallization, using method of Thermal -

Derivative and Electric - Derivative (ATD - AED) method [5].

In the Fig. 2 are shown microstructures of the AlSi11 alloy,

obtained in result of the implemented processes of refining and

modification with strontium or antimony.

In the Fig. 3 are shown graphical records of the crystallization

curves: temperature curve, t = f(τ), and electric conductance

curve, σ = f(τ), in function of time, as well as their first order

derivatives according to the ATD - AED method, for the AlSi11

alloy after refining and modification with strontium or antimony.

Effect of the accomplished upgrading processes on changes

visible on crystallization curves, graphical record of the ATD -

AED method, is confirmed by obtained microstructures.

Microstructures of the investigated alloy, obtained in result of the

upgrading processes, illustrate very distinct differences in shape

of crystallized, basal phases (dendritic crystals - phase α and

eutectic mixture - α + Si), constituting structure of the casting.

High differences in morphology of structures and kinetics

of crystallization of the AlSi11 alloy, arisen in result of performed

metallurgical processes have an effect on changes of mechanical

properties.

In course of the investigations performed earlier one pointed

out that in case of commercial alloys there exits a possibility that

the impurities can have form of oxides and non-metallic

inclusions [3, 4, 6, 8]. Analysis of the obtained test results proves

necessity of accomplishment of filtration processes during casting

process of reliable machinery components.

In the Fig. 4 are shown microstructures of flooded ducts

of foamed filter with visible, blocked impurities after filtering

of the alloy.

Effect of the upgrading method on changes of mechanical

properties (Rm, A5, HB and KCV) of the AlSi11 alloy, destined to

fire-fighting equipment castings, is illustrated in form of bar

charts in the Fig. 5. Numerical values constitute arithmetic mean

from three poured samples.


a)

Magn. 100X

Magn. 500X

b)

Magn. 100X

Magn. 500X

c)

Magn. 100X

Magn. 500X

Fig. 2. Microstructures of the upgraded AlSi11 alloy: a – refined alloy, b – alloy modified with strontium,

c – alloy modified with antimony


Fig. 3. Comparison of crystallization curves of the AlSi11 (AK11) alloy after modification with strontium and antimony

Fig. 4. View of the flooded filter and microstructure with blocked impurities after process of filtering of the AlSi11 (AK11)alloy:

a – cross - section of the flooded filter, b – shape and distribution of blocked impurities

a) b)


Fig. 5. Mechanical properties of the AlSi11 (AK11)alloy, after various processes of upgrading

3. Summary

Developed research methodology and test results obtained on

base of this methodology enable preparation of the AlSi11

(AK11)alloy destined to casting of reliable fire-fighting

equipment from pig sows.

Performed investigations concerning development of the most

advantageous upgrading processes of the AlSi11 (AK11) alloy,

enable production of a castings which feature mechanical and

technological properties required by the PN-91/M-51031 and PN-

91/M-51038 standards (Fire-fighting equipment). However, to

obtain mechanical properties required by the PN-EN 1706: 2001

standard, during melting it is necessary to perform modification

with strontium or antimony.

After modification of the alloy with Sr or Sb, comparing with

refined alloy, one obtained upgraded structure. Eutecic mixture

α + Si, differing each other with respect to shape, has been

crystallized within interdendritic spaces of the phase α. It contains

reduced in size morphology of eutectic silicon, significantly

inpacting on growth of the mechanical properties.

Modification of the alloy has confirmed its significant effect

on change of kinetics of crystallization processes of the

investigated silumin. Extend and character of the obtained

changes is seen on curves of graphical records of the ATD - AED

method.

Developed and set into production upgrading technology

of the AlSi11 (AK11)alloy enables casting of fire-fighting

equipment, which complies with requirements of the European

Union.


Acknowledgements

This work was financed by Project; FSN-T, NOT, No ROW -

22/2009 - Poland.

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of silumins. WNT (Scientific & Technical Publishing House), Warsaw 1989 (in Polish)

[2] Pietrowski S.: Silumins. Publishing House of Lodz Technical University (2001)

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Documents

Physicochemical preparation of the AlSi11 alloy for ... · bFoundry Co - operative in Ustron, 43 - 450 Ustroń, 9 Harbutowicka St., Poland *Corresponding author. E-mail address: [email protected]