what material are water closet bolts often made out of due to corrosion resistance?

Aluminium is the earth's about arable metal and is the third most common chemical element comprising 8% of the earth's chaff. The versatility of aluminium makes it the most widely used metal after steel.

Aluminium Alloys Explained

Production of Aluminium

Aluminium is derived from the mineral bauxite. Bauxite is converted to aluminium oxide (alumina) via the Bayer Process. The alumina is then converted to aluminium metal using electrolytic cells and the Hall-Heroult Process.

Annual Demand of Aluminium

Worldwide demand for aluminium is effectually 29 million tons per year. About 22 1000000 tons is new aluminium and 7 million tons is recycled aluminium scrap. The apply of recycled aluminium is economically and environmentally compelling. It takes fourteen,000 kWh to produce one tonne of new aluminium. Conversely information technology takes only 5% of this to remelt and recycle ane tonne of aluminium. There is no difference in quality betwixt virgin and recycled aluminium alloys.

Applications of Aluminium

Pure aluminium is soft, ductile, corrosion resistant and has a high electrical conductivity. It is widely used for foil and conductor cables, but alloying with other elements is necessary to provide the higher strengths needed for other applications. Aluminium is one of the lightest engineering metals, having a strength to weight ratio superior to steel.

By utilising various combinations of its advantageous properties such as strength, lightness, corrosion resistance, recyclability and formability, aluminium is beingness employed in an ever-increasing number of applications. This array of products ranges from structural materials through to thin packaging foils.

Alloy Designations

Aluminium is virtually commonly alloyed with copper, zinc, magnesium, silicon, manganese and lithium. Small additions of chromium, titanium, zirconium, pb, bismuth and nickel are as well fabricated and iron is invariably present in small quantities.

There are over 300 wrought alloys with fifty in common utilize. They are normally identified by a iv figure system which originated in the Us and is now universally accepted. Tabular array i describes the organisation for wrought alloys. Cast alloys have similar designations and use a 5 digit arrangement.

Tabular array 1. Designations for wrought aluminium alloys.

Alloying Chemical element	Wrought
None (99%+ Aluminium)	1XXX
Copper	2XXX
Manganese	3XXX
Silicon	4XXX
Magnesium	5XXX
Magnesium + Silicon	6XXX
Zinc	7XXX
Lithium	8XXX

For unalloyed wrought aluminium alloys designated 1XXX, the last ii digits represent the purity of the metal. They are the equivalent to the terminal two digits later on the decimal point when aluminium purity is expressed to the nearest 0.01 percent. The second digit indicates modifications in impurity limits. If the second digit is cipher, it indicates unalloyed aluminium having natural impurity limits and i through 9, bespeak individual impurities or alloying elements.

For the 2XXX to 8XXX groups, the last 2 digits identify unlike aluminium alloys in the group. The 2d digit indicates alloy modifications. A 2nd digit of zilch indicates the original alloy and integers 1 to nine indicate sequent alloy modifications.

Physical Properties of Aluminium

Density of Aluminium

Aluminium has a density around i tertiary that of steel or copper making information technology one of the lightest commercially bachelor metals. The resultant high strength to weight ratio makes it an important structural textile allowing increased payloads or fuel savings for send industries in particular.

Strength of Aluminium

Pure aluminium doesn't have a loftier tensile strength. Even so, the addition of alloying elements like manganese, silicon, copper and magnesium tin increase the strength properties of aluminium and produce an blend with backdrop tailored to detail applications.

Aluminium is well suited to cold environments. Information technology has the advantage over steel in that its' tensile strength increases with decreasing temperature while retaining its toughness. Steel on the other manus becomes brittle at low temperatures.

Corrosion Resistance of Aluminium

When exposed to air, a layer of aluminium oxide forms almost instantaneously on the surface of aluminium. This layer has excellent resistance to corrosion. It is adequately resistant to most acids but less resistant to alkalis.

Thermal Conductivity of Aluminium

The thermal conductivity of aluminium is virtually iii times greater than that of steel. This makes aluminium an important textile for both cooling and heating applications such as rut-exchangers. Combined with information technology being non-toxic this property ways aluminium is used extensively in cooking utensils and kitchenware.

Electric Conductivity of Aluminium

Along with copper, aluminium has an electrical electrical conductivity high enough for utilise as an electrical conductor. Although the conductivity of the unremarkably used conducting alloy (1350) is merely around 62% of annealed copper, it is only ane third the weight and tin can therefore acquit twice as much electricity when compared with copper of the aforementioned weight.

Reflectivity of Aluminium

From UV to infra-carmine, aluminium is an excellent reflector of radiant energy. Visible light reflectivity of effectually lxxx% means it is widely used in light fixtures. The same properties of reflectivity makes aluminium ideal equally an insulating material to protect confronting the sun'due south rays in summer, while insulating confronting oestrus loss in winter.

Table 2. Backdrop for aluminium.

Property	Value
Atomic Number	thirteen
Atomic Weight (g/mol)	26.98
Valency	3
Crystal Structure	FCC
Melting Point (°C)	660.two
Boiling Signal (°C)	2480
Mean Specific Oestrus (0-100°C) (cal/g.°C)	0.219
Thermal Conductivity (0-100°C) (cal/cms. °C)	0.57
Co-Efficient of Linear Expansion (0-100°C) (x10^-vi/°C)	23.5
Electrical Resistivity at twenty°C (Ω.cm)	2.69
Density (g/cm³)	ii.6898
Modulus of Elasticity (GPa)	68.3
Poissons Ratio	0.34

Mechanical Properties of Aluminium

Aluminium tin can be severely deformed without failure. This allows aluminium to be formed by rolling, extruding, drawing, machining and other mechanical processes. It tin can likewise be cast to a high tolerance.

Alloying, common cold working and heat-treating can all be utilised to tailor the backdrop of aluminium.

The tensile strength of pure aluminium is around 90 MPa merely this can be increased to over 690 MPa for some estrus-treatable alloys.

Table 3. Mechanical properties of selected aluminium alloys.

Alloy	Temper	Proof Stress 0.20% (MPa)	Tensile Strength (MPa)	Shear Strength (MPa)	Elongation A5 (%)	Elongation A50 (%)	Hardness Brinell HB	Hardness Vickers HV	Fatigue Endur. Limit (MPa)
AA1050A	H2	85	100	60	12		xxx	30
	H4	105	115	70	10	9	35	36	70
	H6	120	130	lxxx	7		39
	H8	140	150	85	6	v	43	44	100
	H9	170	180			3	48	51
	0	35	eighty	l	42	38	21	20	fifty
AA2011	T3	290	365	220	15	fifteen	95	100	250
	T4	270	350	210	18	xviii	xc	95	250
	T6	300	395	235	12	12	110	115	250
	T8	315	420	250	13	12	115	120	250
AA3103	H2	115	135	80	eleven	11	40	40
	H4	140	155	90	9	nine	45	46	130
	H6	160	175	100	viii	6	fifty	l
	H8	180	200	110	vi	6	55	55	150
	H9	210	240	125	4	3	65	70
	0	45	105	seventy	29	25	29	29	100
AA5083	H2	240	330	185	17	16	90	95	280
	H4	275	360	200	16	14	100	105	280
	H6	305	380	210	10	9	105	110
	H8	335	400	220	nine	8	110	115
	H9	370	420	230	five	5	115	120
	0	145	300	175	23	22	70	75	250
AA5251	H2	165	210	125	14	xiv	60	65
	H4	190	230	135	xiii	12	65	70	230
	H6	215	255	145	9	8	70	75
	H8	240	280	155	8	7	eighty	80	250
	H9	270	310	165	v	4	xc	90
	0	fourscore	180	115	26	25	45	46	200
AA5754	H2	185	245	150	15	14	70	75
	H4	215	270	160	14	12	75	80	250
	H6	245	290	170	10	9	80	85
	H8	270	315	180	9	8	90	90	280
	H9	300	340	190	5	four	95	100
	0	100	215	140	25	24	55	55	220
AA6063	0	50	100	70	27	26	25	85	110
	T1	ninety	150	95	26	24	45	45	150
	T4	90	160	110	21	21	50	50	150
	T5	175	215	135	14	13	threescore	65	150
	T6	210	245	150	14	12	75	80	150
	T8	240	260	155		9	80	85
AA6082	0	60	130	85	27	26	35	35	120
	T1	170	260	155	24	24	70	75	200
	T4	170	260	170	19	19	seventy	75	200
	T5	275	325	195	11	xi	90	95	210
	T6	310	340	210	xi	eleven	95	100	210
AA6262	T6	240	290		8
AA6262	T9	330	360		iii
AA7075	0	105	225	150		17	60	65	230
	T6	505	570	350	x	10	150	160	300
	T7	435	505	305	13	12	140	150	300

Aluminium Standards

The sometime BS1470 standard has been replaced by ix EN standards. The EN standards are given in table iv.

Table 4. EN standards for aluminium

Standard	Telescopic
EN485-1	Technical weather condition for inspection and delivery
EN485-two	Mechanical backdrop
EN485-3	Tolerances for hot rolled material
EN485-four	Tolerances for cold rolled material
EN515	Temper designations
EN573-1	Numerical blend designation system
EN573-2	Chemical symbol designation organization
EN573-iii	Chemical compositions
EN573-4	Product forms in different alloys

The EN standards differ from the old standard, BS1470 in the following areas:

Chemical compositions – unchanged.
Blend numbering system – unchanged.
Temper designations for heat treatable alloys at present cover a wider range of special tempers. Up to four digits after the T have been introduced for not- standard applications (e.g. T6151).
Temper designations for not heat treatable alloys – existing tempers are unchanged but tempers are now more comprehensively divers in terms of how they are created. Soft (O) temper is at present H111 and an intermediate temper H112 has been introduced. For alloy 5251 tempers are now shown as H32/H34/H36/H38 (equivalent to H22/H24, etc). H19/H22 & H24 are now shown separately.
Mechanical properties – remain like to previous figures. 0.two% Proof Stress must now exist quoted on test certificates.
Tolerances have been tightened to various degrees.

Estrus Treatment of Aluminium

A range of heat treatments tin be applied to aluminium alloys:

Homogenisation – the removal of segregation by heating afterwards casting.
Annealing – used after cold working to soften work-hardening alloys (1XXX, 3XXX and 5XXX).
Precipitation or age hardening (alloys 2XXX, 6XXX and 7XXX).
Solution heat treatment earlier ageing of precipitation hardening alloys.
Stoving for the curing of coatings
After heat treatment a suffix is added to the designation numbers.
The suffix F means "as made".
O means "annealed wrought products".
T means that information technology has been "estrus treated".
W means the material has been solution heat treated.
H refers to not oestrus treatable alloys that are "cold worked" or "strain hardened".

The non-oestrus treatable alloys are those in the 3XXX, 4XXX and 5XXX groups.

Table 5. Heat treatment designations for aluminium and aluminium alloys.

Term	Description
T1	Cooled from an elevated temperature shaping procedure and naturally aged.
T2	Cooled from an elevated temperature shaping process common cold worked and naturally aged.
T3	Solution estrus-treated cold worked and naturally aged to a substantially.
T4	Solution heat-treated and naturally aged to a substantially stable condition.
T5	Cooled from an elevated temperature shaping procedure and then artificially aged.
T6	Solution rut-treated and then artificially aged.
T7	Solution heat-treated and overaged/stabilised.

Work Hardening of Aluminium

The non-heat treatable alloys can have their properties adjusted by cold working. Cold rolling is an example.

These adjusted properties depend upon the degree of cold work and whether working is followed by any annealing or stabilising thermal treatment.

Nomenclature to draw these treatments uses a letter of the alphabet, O, F or H followed by one or more numbers. As outlined in Table 6, the showtime number refers to the worked condition and the second number the degree of tempering.

Tabular array half dozen. Non-Heat treatable alloy designations

Term	Description
H1X	Work hardened
H2X	Piece of work hardened and partially annealed
H3X	Work hardened and stabilized past low temperature handling
H4X	Work hardened and stoved
HX2	Quarter-difficult – caste of working
HX4	Half-difficult – caste of working
HX6	Iii-quarter hard – degree of working
HX8	Full-difficult – degree of working

Tabular array vii. Temper codes for plate

Code	Description
H112	Alloys that take some tempering from shaping merely do not have special command over the amount of strain-hardening or thermal treatment. Some strength limits apply.
H321	Strain hardened to an amount less than required for a controlled H32 atmosphere.
H323	A version of H32 that has been hardened to provide adequate resistance to stress corrosion cracking.
H343	A version of H34 that has been hardened to provide acceptable resistance to stress corrosion not bad.
H115	Armour plate.
H116	Special corrosion-resistant atmosphere.

DISCLAIMER

This Data is indicative but and must not be seen as a substitute for the total specification from which it is drawn. In item, the mechanical property requirements vary widely with temper, product and product dimensions. The information is based on our nowadays cognition and is given in good religion. Nevertheless, no liability volition be accepted by the Company is respect of any action taken by whatsoever third party in reliance thereon.

Every bit the products detailed may be used for a wide diverseness of purposes and as the Company has no control over their use; the Visitor specifically excludes all atmospheric condition or warranties expressed or implied by statute or otherwise as to dimensions, properties and/or fitness for any particular purpose.

Whatever communication given by the Company to any third party is given for that party's aid only and without liability on the part of the Company. Whatsoever contract between the Company and a client will be bailiwick to the company's Conditions of Sale. The extent of the Company's liabilities to any customer is clearly set out in those Conditions; a copy of which is bachelor on asking.

This information has been sourced, reviewed and adapted from materials provided by Aalco - Ferrous and Non-Ferrous Metals Stockist.

For more information on this source, please visit Aalco - Ferrous and Non-Ferrous Metals Stockist.

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