1
Aluminium Alloy
1.1 Wrought Aluminium and Aluminium Alloy Designation System

A system of four-digit numerical designations in used to
identify wrought aluminium and wrought aluminium alloys. The first digit indicates the alloy group as follows:
 
1.1.1Non-heat-treatable alloys : 1xxx, 3xxx, 4xxx, 5xxx
Aluminium 99% minimum and greater------------------------------- 1xxx
Aluminium alloys grouped by major alloying element
Manganese------------------------------------------------------- 3xxx
Silicon--------------------------------------------------------- 4xxx
Magnesium------------------------------------------------------- 5xxx
1.1.2Heat-treatable alloys : 2xxx, 6xxx, 7xxx
Copper---------------------------------------------------------- 2xxx
Magnesium and Silicon------------------------------------------- 6xxx
Zinc------------------------------------------------------------ 7xxx
 
1.2 Alloy No.

At present we used the alloy no. of Aluminium Association. For example :
 1070-H14 ( Aluminium 99%)
 5052-H32 (Non-heat-treatable alloys)

 6061-T6 (Heat-treatable alloys)

 

2.1The last two digits identify the aluminium alloy or indicate the aluminium purity. The second digit indicates modifications of the original alloy or impurity limits.

2
Temper Designation System

 The temper designation system is used for all forms of wrought and cast aluminium and aluminium alloys except ingot. It is based on the sequences of basic treatments used to produce the various temper. The temper designation follows the alloy designation, the two being separated by a hyphen. Basic temper designations consist of letters. Subdivisions of the basic tempers, where required, are indicated by one or more digits following the letter. These designate specific sequences of basic treatments, but only operations recognized as significantly influencing the characteristics of the product are indicated. Should some other variation of the same sequence of basic operations be applied to the same alloy, resulting in different characteristics, then additional digits are added to the designation.

2.1.Baic temper designation
 
Temper
Designation
F
as fabricated.

Applies to the products of shaping processes in which no special control over thermal conditions or strain hardening is employed. For wrought products, there are no mechanical property limits.
H112
Applies to products that may acquire some tempter from working at an elevated temperature and for which there are mechanical property limits.
O
annealed.

Applies to the wrought products that are annealed to obtain the lowest strength temper, and o cast products that are annealed to improve ductility and dimensional stability. The O may be followed by a digit other than zero.
H
strain-hardened (wrought products only).

Applies to products that have their strength increased by strain-hardening. With or without supplementary thermal treatments to produce some reduction in strength. The H is always followed by two or more digits.

H1n:
strain-hardened only
H2n:
strain-hardened and partially annealed
H3n:
strain-hardened and stabilized
Numeral 8 has been assigned to the hardest tempers normally produced.

n=4 designates tempers whose ultimate tensile strength is approximately midway between that of the O temper and that of the HX8 tempers.

n=2 designates tempers whose ultimate tensile strength is approximately between that of the O temper and that of the HX4 tempers.

n=6 designates tempers whose ultimate tensile strength is approximately midway between that of the HX8 temper and that of the HX4 tempers.

n=9 designates tempers whose min ultimate tensile strength is approximately exceeds that of the HX8 temper by 2 ksi or more.

T
thermally treated to produce stable tempers other than F, O, or H. Applies to products that are thermally treated, with or without supplementary strain-hardening, to produce stable tempers. The T is always followed by one or more digits.

T1 : cooled from an elevated temperature shaping process and naturally aged to a substantially stable condition.

T3 : solution heat-treated, cold worked, and naturally aged to a substantially stable condition.

T4 : solution heat-treated, and naturally aged to a substantially stable condition.

T5 : cooled from an elevated temperature shaping process and then artificially aged.

T6 : solution heat-treated, and then artificially aged.

T7 : solution heat-treated and overaged / stabilized.

T8 : solution heat-treated, cold worked, and then then artificially aged.

T9 : solution heat-treated, artificially aged, and the cold worked.

3
Working Knowledge

1.The Normal Defect of Sulfuric Acid Anodizing Treatment
 
Defect
Happened Reason
Improvement Method
Local spark or penetrate of worked piece
1. short circuit between worked piece and cathod
1. prevent touch cathode during put worked piec
2. short circuit between worked pieces
2. increased the distance between worked pieces
3. contact failure between worked piece and holder
3. holder must be cleaned before usage, and contact must be tight with worked piece
Oxidizing film too soften, and easy to take out
1. the temperature of electrolyte is too high
1. used stirring or cooling system to decrease the temperature of electrolyte, and control the difference between +/-2oC
2. treatment time is too long
2. short the treatment time
3. the working circuit density is too high
3. decreased the working circuit density
Oxidizing film have red spot, or surface color changed to red
1. contact failure between conducting bar and holder to induce the copper penetrate on the surface of worked piece
1. improve the contact between conducting bar and holder, and changed bar material to aluminum
2. conducting failure
2. increase the checking frequency of equipment during treatment
Oxidizing film bright too dark, or burned
1. worked piece have long time not to treatment on the tank, or recharged after closed treatment
1. increase checking frequency and control the maintenance period of electric equipment
2. the solved aluminum concentration of electrolyte is too high, induced to penetration of film too dark, or burned
2. check the solved aluminum content
 
2.1 the content is limited at 1 gm/l
 
2.2 new electrolyte added 12~13 gm/l of aluminum sulfate
Oxidizing film have black spot or black banded mark
1. the electrolyte have suspension impurity
1. clean the electrolyte
2. worked piece have oil stein or other dirty on surface
2. check the degrease agent composition, make sure of pretreatment
3. the copper and iron impurity of electrolyte are too high
3. clean the electrolyte after analysis, and partial change at certain period
4. worked piece after anodizing is not cleaned before closed treatment
4. worked piece must be cleaned after anodizing, to prevent remain the electrolyte or impurity on the surface
Local corrosion of oxidizing film
1. the electrolyte is not clean after oxidizing treatment
1. increased the clean procedure
2. the residual electrolyte is not clean on deep draw area
2. increased the clean procedure
3. the closed treatment is doing before clean the electrolyte
3. increased the clean procedure
Oxidizing film color change to light and too white after doping potassium chromate
1. the temperature of electrolyte is too low, and filling time too short
1. improve the treating condition
2. the content of sulfate ion is too high
2. checking and adjusting the content of sulfate ion
3. the thickness of oxidizing film too thin
3. increase the oxidizing treatment time
The thickness of oxidizing film is non-uniform
1. the surface of worked piece have dirty not to clean
1. strongly apply the practice of pretreatment to clean surface
2. the stirring of treating tank is not uniform
2. strongly the stirring work
3. the circuit density is too high
3. the normal circuit density is 1~2A/dm2
The surface of worked piece is easy to coating hand mark, or water mark, or film color changed to white after closed r treatment of hot water
1. the temperature and time of closed treating is not enough
1. improve the certain treating condition
2. pHvalue is not correct
2. adjusting the pH value
3. the content of aluminum hydrate of solution is too high
3. changed the water
 
2.The Normal Defect of Chromate Acid Anodizing Treatment
 
Defect
Happened Reason
Improvement Method
Worked piece is burned
1. contact failure between worked piece and holder
1. improve the contact between conducting bar and holder
2. contact between worked piece and cathode, or between worked piece itself
2. prevent the contact
3. The voltage is too high
3. decrease the voltage
Worked piece is corroded to create deep hole
1. the CrO3content of electrolyte is not too low
1. increased the CrO3content
2. the alloy have defect on itself, or it's composition non-homogeneous
2. change material
Oxidizing film too thin, and color is changed to white
1. contact failure between conducting bar and holder
1. improve the contact between conducting bar and holder
2. the oxidizing time too short
2. increase the oxidizing treatment time
3. the circuit density is too small
3. adjust the circuit density
Oxidizing film have powder on the surface
1. the temperature of electrolyte is too high
1. adjust the temperature
2. the circuit density is too high
2. adjust the circuit density
Oxidizing film color is changed to black
1. the polish gel is not clean on the worked piece surface

1. increased the clean procedure
2. the worked piece itself have problem
2. change worked piece
Oxidizing film surface color changed to red
1. pretreatment is not completed
1. improve the pretreatment procedure
2. contact failure between conducting bar and holder
2. improve the contact situation
 
3.The Normal Defect of Hard Coating Anodizing Treatment
 
Defect
Happened Reason
Improvement Method
The thickness of oxidizing is not enough
1. the oxidizing time is too short
1. increase the oxidizing time
2. the circuit density is too low
2. increase the circuit density
3. the oxidizing area calculation is non-correct
3. re-correct the worked piece oxidizing area
The hardness of oxidizing film is too low
1. the temperature of electrolyte is too high
1. decrease the temperature of electrolyte
2. the circuit density is too high
2. decrease the circuit density
3. the thickness of oxidizing is too thick
3. short the oxidizing time
The oxidizing film is penetrated, and the worked piece is burned
1. the copper content of alloy is too high
1. change the alloy
2. the heat radiate is not good
2. increase the stirring and cooling of electrolyte
3. the contact failure between worked piece and holder
3. improve the contact
4. the charged of oxidizing is too fast
4. improve the working procedure
 
4.The Normal Defect of Aluminum Forming
 
Defect
Happened Reason
Improvement Method
Material have defect
 
1. the hollow shell or the raised edge of the material, have crack
1. the tumble defect
1. improve the quality control
2. creat protruding
2. the mechanical characteristics is too uniform
2. annealing (not induce the grain growth)
Tool have defect

 
1. the bottom of hollow shell is tearing at start of deep drawing
1. the corner of head or die is too sharp
1. increase the corner redial
2. the bottom of hollow shell is tearing at final of deep drawing
2. drawing ratio is too large, the head is not aim with die center
2. increase middle drawing, select the good material; if the material is square hollow shell, it is increase the corner space between head and die
3. drawing scratch
3. lubrication is not good, the tool surface condition is not good (already wear)
3. use special grease oil for drawing (material must be surface treatment by phosphate or copper coating), glossy the tool surface(coating chromium), select the resistant scratch material
4. the fringe of finish have zigzag, shell surface have fold
4. corner of die is too large, the space between head and die is too large
4. change the die or change the tool set
Tool or equipment adjusting to create defect    
1. the fringe have fold
1. the pressure of material holding frame is too low
1. increase holding frame pressure
2. the side of finish have grab, or other defect, tool surface also have defect
2. the head aim with die center, or tilt, to create the wear
2. regrind the tool or change the tool set
3. shell surface too rough, esp., rectangle deep drawing finish
3. the pressure of material holding frame is too low, or the die corner is too large
3.  
increase holding frame pressure, or insert tower between die and holding frame
4. shell line have flatten fold or crack
4. the pressure of material holding frame is too low, or the space between die and head is too large
4. change the tool set



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