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The welding of aluminium castings  Tony Paterson
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting  </li></ul><ul><l...
What is a casting? <ul><li>three dimensional shape formed from the melt (highly complex shapes possible) </li></ul><ul><li...
Why  weld a Casting ? <ul><li>Join a casting to wrought material </li></ul><ul><li>Joining several castings together </li>...
Why  weld a Casting ? <ul><li>Join a casting to wrought material </li></ul><ul><li>Welding compromises the strength of tem...
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting  </li></ul><ul><l...
Aluminium Casting Designations  Which alloy is which -  Cast Alloy Designations <ul><li>There is no single universally acc...
Aluminium Casting Designations  Cast Alloy Designation (US) <ul><li>US 3 digit number, plus 1 decimal </li></ul><ul><li>  ...
Aluminium Casting Designations  Cast Alloy Designation (US) <ul><li>Example  535.0  is an Al/Mg alloy, with no  modificati...
Aluminium Casting Designations  Cast Alloy Designation (EN) <ul><li>EN 5 digit number  </li></ul><ul><li>  Al+ </li></ul><...
Aluminium Casting Designations  Cast Alloy Designation (EN) <ul><li>Examples:  AC 42100 is an Al/Si/Mg alloy .  AC 45100 i...
Aluminium Casting Designations  Cast Alloy Designation (Chemical) – similar to wrought <ul><li>Chemical designation   (old...
Aluminium Casting Designations  Cast Alloy Designation (BS now superceded) <ul><li>UK discontinued LM series  (unsystemati...
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting  </li></ul><ul><l...
Which castings are weldable ? <ul><li>Process </li></ul><ul><li>Composition </li></ul>
Which castings are weldable ? Process Alloys Processes Wrought alloys All except > 0,25% copper addition -  (some exceptio...
Weldable Cast Alloys <ul><li>Non heat treatable </li></ul><ul><ul><li>EN 44100 (LM6, AlSi12) </li></ul></ul><ul><ul><li>EN...
Which castings are weldable ? Composition  <ul><li>Based on aluminium silicon </li></ul><ul><li>Main elemental additions o...
Aluminium 660 o C 231 o C- 327 o C  Se, Sn, Bi, Cd, Pb,  97,7 o C Na 44.2 o C P-  650 o C Mg  630 o C Sb  420 o C Zn  1410...
Which castings are weldable ? Composition – cf wrought alloys
Which castings are weldable ? Composition relationship between filler/parent metal and weld cracking –  (Note: long copper...
Which c astings are weldable ? Compostion   NOTE  Log scale!  l n  Cu upper limit % (wrought and cast alloys) (Other alloy...
Silicon <ul><li>Si improves fluidity, feeding and hot tear resistance. </li></ul><ul><li>Si increases hardness, reduces du...
Copper <ul><li>Basis of heat treatable alloys </li></ul><ul><li>Improves strength, hardness, thermal conductivity </li></u...
Iron <ul><li>Normally not added but picked up from furnace  </li></ul><ul><li>Forms many intermetallic phases </li></ul><u...
Magnesium <ul><li>Strengthening in AlSi alloys </li></ul><ul><li>Premium grade alloys have 0,4 - 0,7%Mg </li></ul><ul><li>...
Lead <ul><li>Added up to 0,35%Pb to improves machinability by enhancing intergranular chip breaking  </li></ul><ul><li>Not...
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting  </li></ul><ul><l...
Designations of comparable casting alloys (unalloyed and aluminium silicon)  CEN Chemical designat-ion  UK BS1450/ AEA  Fr...
Designations of comparable casting alloys (aluminium silicon copper)  CEN Chemical designat-ion  UK BS1450/ AEA  France NF...
Designations of comparable casting alloys (Aluminium copper/aluminium magnesium and piston alloys)  Note: Designations in ...
Alloys selection for weldability/ corrosion resistance <ul><li>Generally corrosion resistance and weldability run in paral...
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting  </li></ul><ul><l...
Alloys used in RSA <ul><li>EN 44100  (LM6, AlSi12) </li></ul><ul><li>10,5 – 13,5%Si; 0,15%Cu  </li></ul><ul><li>Widely use...
Cast Alloys cont.. <ul><li>EN 46500  (LM24, AlSi9Cu3(Fe)(Zn)) </li></ul><ul><li>8,0 – 11,0%Si; 2,0 – 4,0%Cu; 1,3%Fe; 0,35%...
Cast Alloys cont.. <ul><li>EN 42000  (LM25, AlSi7Mg) </li></ul><ul><li>6,5 – 7,5%Si; 0,2%Cu </li></ul><ul><li>Larger casti...
Cast Alloys cont.. <ul><li>EN 46100  (LM2, ADC12, AlSi11Cu2(Fe)) </li></ul><ul><li>10,0 – 12,0%Si; 1,5 – 2,5%Cu </li></ul>...
Cast Alloys cont.. <ul><li>EN 44000  (ALSi11) </li></ul><ul><li>Very fluid permanent mould alloy </li></ul><ul><li>Traditi...
Cast Alloys cont.. <ul><li>EN 42100  (AlSi7Mg0.3) </li></ul><ul><li>Used for alloy rims, premium aerospace castings, nucle...
Cast Alloys cont.. <ul><li>EN 43100  (LM9, AlSi10Mg) </li></ul><ul><li>10,0 – 11,8%Si; 0,25 – 0,45%Mg </li></ul><ul><li>Mo...
Cast Alloys – filler alloy choice Selection of filler rods and wires for MIG and TIG welding   Parent metal combination LM...
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting  </li></ul><ul><l...
Repair Welding <ul><li>Casting is heat treatable and has been hardened </li></ul><ul><li>Welding will over age HAZ </li></...
Non Heat Treatable Castin g <ul><li>Preheat 100  C up to 8 mm thick </li></ul><ul><ul><li>340 - 400  C for heavy or intr...
Heat Treatable Alloy cont.. <ul><li>Preheat 100 - 400°C (short period to avoid anneal) </li></ul><ul><li>Use 4043 filler m...
Cosmetic Repair <ul><li>Non heat treatable </li></ul><ul><li>Preheat as appropriate </li></ul><ul><li>Clean thoroughly </l...
Cosmetic Repair <ul><li>Heat treatable alloy </li></ul><ul><li>Casting is in ‘as cast’ F temper </li></ul><ul><li>Preheat ...
Welding Multiple Castings <ul><li>Preferably F or T2 condition </li></ul><ul><ul><li>Lowest strength in base metal </li></...
Welding Cast to Wrought <ul><li>Same principles as casting to casting </li></ul><ul><li>Wrought material will lose strengt...
Build-up of Castings <ul><li>Very similar to cosmetic repair procedure </li></ul><ul><li>Depends on alloy and temper </li>...
Aluminium to Steel <ul><li>Very difficult ~ intermetallic compounds, melting temperatures, expansion </li></ul><ul><li>Can...
Aluminium to Copper <ul><li>Used for electrical terminations </li></ul><ul><li>Can coat copper with silver or silver alloy...
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting  </li></ul><ul><l...
General Considerations <ul><li>Avoid unnecessary stresses </li></ul><ul><ul><li>No sudden thickness changes ~ use tapers <...
General Considerations <ul><li>Clean the joint properly </li></ul><ul><ul><li>Aluminium very susceptible to contamination ...
General Considerations <ul><li>Create the right conditions for welding - physical </li></ul><ul><ul><li>Dry (RH<65%), warm...
General Considerations <ul><li>Ensure consumables are suitable </li></ul><ul><ul><li>Gas must be 99,995% pure minimum - no...
Cutting and Preparing Al <ul><li>Cannot use oxy fuel </li></ul><ul><li>Aluminium is not fit up tolerant – cannot fill sign...
Cutting and Preparing Al cont.. <ul><li>Planers, routers and edge mills for edge preparation </li></ul><ul><li>Tungsten ca...
Welding problems Gas porosity in aluminium welds – always caused by hydrogen <ul><li>Low solubility in solid and high solu...
Welding problems Gas porosity in aluminium welds – always caused by hydrogen (Low solubility in solid and high solubility ...
Welding problems - Gas Porosity in welds
Welding problems Cracking in aluminium is always hot cracking <ul><li>Strength of solidifying metal is too low to resist s...
Hot Cracking cont.. <ul><li>Weld bead chemistry - Select suitable filler metal </li></ul><ul><li>Higher alloy content allo...
Welding problems Composition relationship between filler/parent metal and weld cracking –  (Note: long copper sensitivity ...
Good Fair Poor Filler Alloy 5356 Parent Alloy 6061 Filler Alloy 4043  a b d c 1 2 3 4 5 6 Silicon in the Weld Bead (%) 0 1...
<ul><li>Welding of aluminium castings  </li></ul><ul><li>Topics covered: </li></ul><ul><li>What is a casting  </li></ul><u...
The welding of aluminium castings  Tony Paterson (082 602 4517) Questions??
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Welding of aluminium castings - October 2011

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Welding of Aluminium Casting by Dr Tony Patterson, AFSA

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  • Transcript of "Welding of aluminium castings - October 2011"

    1. 1. The welding of aluminium castings Tony Paterson
    2. 2. <ul><li>Welding of aluminium castings </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    3. 3. What is a casting? <ul><li>three dimensional shape formed from the melt (highly complex shapes possible) </li></ul><ul><li>cf wrought flats - one dimensional (thickness) </li></ul><ul><li>wrought extrusions – two dimensional </li></ul><ul><li>wrought forgings – simpler three dimensional </li></ul><ul><li>(hot or cold formed from solid or semi solid cast) </li></ul><ul><li>Generally non homogenous structure due to directional solidification </li></ul><ul><li>Produced using various processes (sand, permanent mould (gravity and low pressure – laminar flow), high pressure die casting </li></ul>
    4. 4. Why weld a Casting ? <ul><li>Join a casting to wrought material </li></ul><ul><li>Joining several castings together </li></ul><ul><li>Build up a casting </li></ul><ul><ul><li>Worn area or manufacturing </li></ul></ul><ul><li>Join casting to other metal </li></ul><ul><li>Physical damage to old casting </li></ul><ul><li>Repair of superficial defect in a new casting </li></ul><ul><li>Repair of unavoidable shrinkage porosity in new casting </li></ul><ul><li>Note that not all castings are weldable </li></ul>
    5. 5. Why weld a Casting ? <ul><li>Join a casting to wrought material </li></ul><ul><li>Welding compromises the strength of tempered aluminium because it reverses the temper effect </li></ul><ul><li>It is desirable to choose the position and nature of welds to limit the impact of this loss of strength. </li></ul><ul><li>From a structural point of view a casting forms a good corner stress transfer unit in three dimensional structural applications as it potentially displaces welds to low stress areas. </li></ul><ul><li>Whilst adhesive bonding is sometimes called for, some casting alloys are weldable. </li></ul>
    6. 6. <ul><li>Welding of aluminium castings </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    7. 7. Aluminium Casting Designations Which alloy is which - Cast Alloy Designations <ul><li>There is no single universally accepted designation system </li></ul><ul><li>Designations systems include: </li></ul><ul><li>US 3 digit number, plus 1 decimal </li></ul><ul><li>EN 5 digit number (RSA standard since 1990’s) </li></ul><ul><li>Chemical designations (eg old DIN) </li></ul><ul><li>UK discontinued LM series still commonly cited in RSA </li></ul><ul><li>Others – eg old eastern Europe </li></ul><ul><li>Others Far East – including Japan </li></ul><ul><li>Note: From a welding point of view we need to understand which alloy we are dealing with as not all are weldable – in particular most Cu (2xx.x)and ZnCu (7xx.x) alloys are practically unweldable. </li></ul><ul><li>There are exceptions. </li></ul><ul><li> </li></ul>
    8. 8. Aluminium Casting Designations Cast Alloy Designation (US) <ul><li>US 3 digit number, plus 1 decimal </li></ul><ul><li> Al+ </li></ul><ul><li> Cu Si/Cu/Mg Si Mg Zn Sn Other </li></ul><ul><li>1xx.x 2xx.x 3xx.x 4xx.x 5xx.x 7xx.x 8xx.x 9xx.x </li></ul><ul><li>Non-heat-treatable </li></ul><ul><li>Heat-treatable </li></ul>
    9. 9. Aluminium Casting Designations Cast Alloy Designation (US) <ul><li>Example 535.0 is an Al/Mg alloy, with no modification, assigned alloy number 35, for final casting </li></ul>A X XX .X Principle Alloying Element Alloy Number Form - Final Casting (.0) or Ingot (.1 or .2)* *Depending on Purity Limits (Modifications (sometimes have a prefix [A,B,C]) depending on the element
    10. 10. Aluminium Casting Designations Cast Alloy Designation (EN) <ul><li>EN 5 digit number </li></ul><ul><li> Al+ </li></ul><ul><li>Cu Si/Mg Si/Cu/Mg Si.12% Mg Zn/Mg Master </li></ul><ul><li>21xxx 41xxx 45xxx 44xxx 51xxx 71xxx 9xxxx </li></ul><ul><li>42xxx 46xxx </li></ul><ul><li>43xxx 47xxx </li></ul><ul><li>Non-heat-treatable </li></ul><ul><li>Heat-treatable </li></ul>
    11. 11. Aluminium Casting Designations Cast Alloy Designation (EN) <ul><li>Examples: AC 42100 is an Al/Si/Mg alloy . AC 45100 is an Al/Si/Cu/Mg alloy </li></ul>AC X X XXX Principle Alloying Element Alloy Groups (with principal element) Arbitrary Generally 0 0 except for aerospace
    12. 12. Aluminium Casting Designations Cast Alloy Designation (Chemical) – similar to wrought <ul><li>Chemical designation (older German specifications) </li></ul><ul><li> </li></ul><ul><li>First symbol: AB (billet) or AC (casting) or (A) or G (DIN) </li></ul><ul><li>Second symbol: Al </li></ul><ul><li>Third and following: Alpha numeric </li></ul><ul><li>– Alpha - Main element or elements in order of decreasing nominal content (or, if equal, in alphabetical order – up to a maximum of four elements) followed by numbers. </li></ul><ul><li>- Numeric - represent the mass percentage contents to the nearest 0,5%, or, if less than 1%, the nearest 0,1%) </li></ul><ul><li>Weldability: take care with alloys where Cu>0,25 -0,4% </li></ul>
    13. 13. Aluminium Casting Designations Cast Alloy Designation (BS now superceded) <ul><li>UK discontinued LM series (unsystematic – WW2 base) </li></ul><ul><li>Still used in RSA and cited in reference literature </li></ul><ul><li> Al </li></ul><ul><li> Cu Si/Cu Si/Mg Mg Other (piston) </li></ul><ul><li>LM0 LM2 LM6 LM5 LM28 </li></ul><ul><li>LM4 LM9 LM13 </li></ul><ul><li>LM20 LM25 </li></ul><ul><li>LM21 </li></ul><ul><li>LM22 </li></ul><ul><li>LM24 </li></ul><ul><li>Non -heat-treatable </li></ul><ul><li>Heat-treatable </li></ul>
    14. 14. <ul><li>Welding of aluminium castings </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    15. 15. Which castings are weldable ? <ul><li>Process </li></ul><ul><li>Composition </li></ul>
    16. 16. Which castings are weldable ? Process Alloys Processes Wrought alloys All except > 0,25% copper addition - (some exceptions <0,4%) and free machining alloys All - Rolling, extrusion, forging, etc Cast alloys All except > 0,25% copper additions, and free machining alloys Sand, gravity, permanent mould, low pressure. Not standard high pressure die casting (i.e . unless vacuum cast.)
    17. 17. Weldable Cast Alloys <ul><li>Non heat treatable </li></ul><ul><ul><li>EN 44100 (LM6, AlSi12) </li></ul></ul><ul><ul><li>EN 44000 (AlSi11) </li></ul></ul><ul><ul><li>EN 43100 (LM9, AlSi10Mg) </li></ul></ul><ul><ul><li>EN 5100 (LM5) </li></ul></ul><ul><li>Heat treatable </li></ul><ul><ul><li>EN 42000 (LM25, AlSi7Mg) </li></ul></ul><ul><ul><li>EN 42100 (AlSi7Mg0,3) </li></ul></ul>
    18. 18. Which castings are weldable ? Composition <ul><li>Based on aluminium silicon </li></ul><ul><li>Main elemental additions of Cu, Mg, Fe, Mn, Ni, Zn, Pb </li></ul><ul><li>Other elemental additions include a wide additional range. </li></ul><ul><li>Alloy elements modify casting characteristics </li></ul><ul><li>Also influence hardness, fluidity, machinability, weldability , castability </li></ul>
    19. 19. Aluminium 660 o C 231 o C- 327 o C Se, Sn, Bi, Cd, Pb, 97,7 o C Na 44.2 o C P- 650 o C Mg 630 o C Sb 420 o C Zn 1410 o C Si 1245 o C Mn 1150 o C Fe 1083 o C Cu 1852 o C – 2625 o C Zr, Ti, Cr, B, V, Mo Which castings are weldable ? Composition - What do we add - Summary 768 o C Sr hardeners Grain refiners (never melts) Free machining Grain modifiers (casting) affects micro porosity (early freeze c.f. Si) MgSi composition 6xxx
    20. 20. Which castings are weldable ? Composition – cf wrought alloys
    21. 21. Which castings are weldable ? Composition relationship between filler/parent metal and weld cracking – (Note: long copper sensitivity above 0,25%) Dilution by 4043 – thus choose 5356 Dilution by 4043 – avoid 5356 5xxx 6xxx 2xxx
    22. 22. Which c astings are weldable ? Compostion NOTE Log scale! l n Cu upper limit % (wrought and cast alloys) (Other alloy elements, eg silicon, also have a role) Welding Rating Excellent A Very good B Good C Poor D 0.1 0.2 0.3 0.5 1 2 3 3+ ****** (1xxx) ** ******* *** * ** * (3xxx, 5xxx, 51000 (LM0,LM5) ) **** * * ** * (6xxx, LM25, LM6 ) **** * *** ** *** ** ** ** ( LM20 ) * ******** ******** (2xxx, LM4, 21,22,24,26 )
    23. 23. Silicon <ul><li>Si improves fluidity, feeding and hot tear resistance. </li></ul><ul><li>Si increases hardness, reduces ductility & machinability. </li></ul><ul><li>Si content is related to casting process </li></ul><ul><ul><li>Sand casting 5 - 7% Si </li></ul></ul><ul><ul><li>Permanent mould 7 - 9% Si </li></ul></ul><ul><ul><li>Die casting 8 - 12% Si </li></ul></ul>
    24. 24. Copper <ul><li>Basis of heat treatable alloys </li></ul><ul><li>Improves strength, hardness, thermal conductivity </li></ul><ul><li>Decreases castability and hot tear resistance </li></ul><ul><li>Allows most hardening in 4 - 6% range </li></ul><ul><li>Copper base alloys above about a 0,4% limit weldability, corrosion resistance and suitability for decoration </li></ul>
    25. 25. Iron <ul><li>Normally not added but picked up from furnace </li></ul><ul><li>Forms many intermetallic phases </li></ul><ul><li>Increases elevated temperature strength </li></ul><ul><li>Improves hot tear resistance </li></ul><ul><li>Reduces ductility </li></ul><ul><li>Too high reduces castability </li></ul><ul><ul><li>Flowability and feeding characteristics </li></ul></ul>
    26. 26. Magnesium <ul><li>Strengthening in AlSi alloys </li></ul><ul><li>Premium grade alloys have 0,4 - 0,7%Mg </li></ul><ul><li>No benefit above 0,7% </li></ul><ul><li>High corrosion resistance </li></ul>
    27. 27. Lead <ul><li>Added up to 0,35%Pb to improves machinability by enhancing intergranular chip breaking </li></ul><ul><li>Not suited to food grade products as these limit lead to 0,05% </li></ul>
    28. 28. <ul><li>Welding of aluminium castings </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    29. 29. Designations of comparable casting alloys (unalloyed and aluminium silicon) CEN Chemical designat-ion UK BS1450/ AEA France NF A50 Germany DIN 1725 Italy UNI USA AA / ASTM Japan JIS H5202 H5302 Unalloyed aluminium – generally weldable Al 99,5 LM0 A5 Al99,5H 3950 150.1 Al 99,7 A7 Al99,7H 3950 Aluminium Silicon – generally weldable 42000 AlSi7Mg0,3 AEA 44525 (A –S7G03) (G AlSi7Mg) 42100 AlSi7Mg (Fe) LM25 A-S7G03 G- AlSi5Mg 3599 A356,1 AC4C 42200 AlSi7Mg(0,6) AEA 44530 (A-S7G06) (G -AlSi7Mg) A357 43100 AlSi10Mg LM9 A-S10G (G –AlSi10Mg) 3049 A360 AC4A 43200 AlSi10Mg(Cu) (LM9) (A-S9G) A360 44000 AlSi11 (LM9) A-S13 (G –AlSi12) 44100 AlSi12(Fe) LM6 A-S12U G –AlSi12 4514 A413 AC3A 44200 AlSi12 AEA46330 /LM6 A-S13 AC3A 44300 AlSi12(Fe) (LM20) A-S12 (G –AlSi12)
    30. 30. Designations of comparable casting alloys (aluminium silicon copper) CEN Chemical designat-ion UK BS1450/ AEA France NF A50 Germany DIN 1725 Italy UNI USA AA / ASTM Japan JIS H5202 H5302 Aluminium Silicon Copper – generally not weldable 45000 AlSi6Cu4Mn LM21 A-S5UZ G-AlSi6Cu4 7369/4 A308 AC2A 45100 AlSi5Cu3Mg (LM4) (LM22) A-S5U3G (G-AlSi6Cu4) 45200 AlSi5Cu3Mn LM4 A-S5U3 (G-AlSi7Mg) 3052 A319.2 AC2A 45400 AlSi5Cu4Mn LM22 A-S5U G-AlSi6Cu4 3052 A319.2 AC2A 46000 AlSi9Cu3 (LM26) A-S10G A335 AC4B 46100 AlSi9Cu3 LM2 A-S10UG 5067 A384.1 ADC12 46200 AlSi9Cu3(Fe) (LM24) A-SGU3 46500 AlSi9Cu3(Fe)(Zn) LM24 A-S9U3 G-AlSi8Cu3 5075/3601 A380.1 AC4B/ ADC10 47000 AlSi12(Cu) LM20 A-S12 G-AlSi12(Cu) 5079 A313.1 47100 AlSi12Cu1 (Fe) (LM6)(LM20) A-S12 G-AlSi12(Cu)
    31. 31. Designations of comparable casting alloys (Aluminium copper/aluminium magnesium and piston alloys) Note: Designations in brackets are considered fairly comparable For export purposes the LM series is not recognised CEN Chemical designat-ion UK BS1450/ AEA France NF A50 Germany DIN 1725 Italy UNI USA AA / ASTM Japan JIS H5202 H5302 Aluminium Copper – not weldable 21000 Al Cu4MgTi AEA 24850 A-U5GT A204.2 AC1B Aluminium Magnesium – weldable 51000 AlMg3 LM5 A-G3T G-AlSiMg5 3059 Piston Alloys 48100 AlSi18Cu1 Mg1Ni1 LM28 (KS 2811) A392.1 (AC9B) 48000 AlSi12Cu1 Mg1Ni1 LM13 A-S12UN (KS 1275) A336.0 AC8A
    32. 32. Alloys selection for weldability/ corrosion resistance <ul><li>Generally corrosion resistance and weldability run in parallel </li></ul><ul><li>LM0, LM2, LM4, LM5, LM6, LM9, LM21, LM24, LM 25,LM31 (low Cu alloys) resistant to weathering attack </li></ul><ul><li>Other alloys require protection by anodising or organic finishes </li></ul><ul><li>LM0, LM5, LM6, LM9, LM20, LM25, LM31 suited to marine applications </li></ul><ul><li>LM5 best if bright finish to be maintained </li></ul><ul><li>. </li></ul>
    33. 33. <ul><li>Welding of aluminium castings </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    34. 34. Alloys used in RSA <ul><li>EN 44100 (LM6, AlSi12) </li></ul><ul><li>10,5 – 13,5%Si; 0,15%Cu </li></ul><ul><li>Widely used for sand and chill castings </li></ul><ul><li>Poor machinability </li></ul><ul><li>Good weldability </li></ul><ul><li>Not heat treatable </li></ul><ul><li>. </li></ul>
    35. 35. Cast Alloys cont.. <ul><li>EN 46500 (LM24, AlSi9Cu3(Fe)(Zn)) </li></ul><ul><li>8,0 – 11,0%Si; 2,0 – 4,0%Cu; 1,3%Fe; 0,35%Pb </li></ul><ul><li>High strength because of Cu and Fe </li></ul><ul><li>Good castability because of high Si </li></ul><ul><li>Not weldable because of Cu </li></ul><ul><li>Non heat treatable </li></ul><ul><li>. </li></ul>
    36. 36. Cast Alloys cont.. <ul><li>EN 42000 (LM25, AlSi7Mg) </li></ul><ul><li>6,5 – 7,5%Si; 0,2%Cu </li></ul><ul><li>Larger castings ~ cylinder blocks etc. </li></ul><ul><li>High strength </li></ul><ul><li>Good castability </li></ul><ul><li>Heat treatable </li></ul><ul><li>Weldable </li></ul>
    37. 37. Cast Alloys cont.. <ul><li>EN 46100 (LM2, ADC12, AlSi11Cu2(Fe)) </li></ul><ul><li>10,0 – 12,0%Si; 1,5 – 2,5%Cu </li></ul><ul><li>Pressure die casting alloy specifically </li></ul><ul><li>Good castability </li></ul><ul><li>Not weldable </li></ul><ul><li>Non heat treatable </li></ul>
    38. 38. Cast Alloys cont.. <ul><li>EN 44000 (ALSi11) </li></ul><ul><li>Very fluid permanent mould alloy </li></ul><ul><li>Traditionally used for alloy wheels </li></ul><ul><li>Good ductility, moderate strength </li></ul><ul><li>High impact strength </li></ul><ul><li>Non heat treatable </li></ul><ul><li>Weldable </li></ul><ul><li>. </li></ul>
    39. 39. Cast Alloys cont.. <ul><li>EN 42100 (AlSi7Mg0.3) </li></ul><ul><li>Used for alloy rims, premium aerospace castings, nuclear plant, marine parts </li></ul><ul><li>High strength, good ductility </li></ul><ul><li>Good corrosion resistance </li></ul><ul><li>Heat treatable </li></ul><ul><li>Weldable </li></ul>
    40. 40. Cast Alloys cont.. <ul><li>EN 43100 (LM9, AlSi10Mg) </li></ul><ul><li>10,0 – 11,8%Si; 0,25 – 0,45%Mg </li></ul><ul><li>Most fluid permanent mould alloy available </li></ul><ul><li>Used for intricate castings ~ feedability </li></ul><ul><li>Non heat treatable </li></ul><ul><li>Good weldability ~ high ductility </li></ul>
    41. 41. Cast Alloys – filler alloy choice Selection of filler rods and wires for MIG and TIG welding Parent metal combination LM25 LM20 LM9 LM6 LM5 LM4 1070, 1200, 1350, 5251, 5454, 6082, 6061, 6063, 4043 4043 4043 4043 5356 4043 5083 4043 NR 4043 NR 5356 4043 7020 NR NR NR NR 5356/5556 NR LM4 4043 4043 4043 4043 NR 4043 LM5 NR NR NR NR 5356/5056 NR LM6 4043/4047 4043/4047 4043/4047 4043/4047 LM9 4043/4047 4043/4047 4043/4047 LM20 4043/4047 4043/4047 LM25 4043/4047
    42. 42. <ul><li>Welding of aluminium castings </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    43. 43. Repair Welding <ul><li>Casting is heat treatable and has been hardened </li></ul><ul><li>Welding will over age HAZ </li></ul><ul><li>Can do simple repairs in T6 or T7 temper </li></ul><ul><li>Better to weld in F or T2 condition </li></ul><ul><li>Large extensive repairs only in F or T2 </li></ul><ul><li>Anneal before welding </li></ul>
    44. 44. Non Heat Treatable Castin g <ul><li>Preheat 100  C up to 8 mm thick </li></ul><ul><ul><li>340 - 400  C for heavy or intricate castings </li></ul></ul><ul><li>Use 4043 (6%Si) or 4047 (12% Si) filler </li></ul><ul><li>Heat input 0,8 - 1,6 kJ/mm </li></ul><ul><li>Slow cool </li></ul><ul><li>Weld strength very close to base metal </li></ul>
    45. 45. Heat Treatable Alloy cont.. <ul><li>Preheat 100 - 400°C (short period to avoid anneal) </li></ul><ul><li>Use 4043 filler metal </li></ul><ul><li>Solution anneal ~ also stress relieves weld </li></ul><ul><li>Heat treat as required – but 4043 NHT </li></ul>
    46. 46. Cosmetic Repair <ul><li>Non heat treatable </li></ul><ul><li>Preheat as appropriate </li></ul><ul><li>Clean thoroughly </li></ul><ul><li>Weld with 4043 or 4047 filler </li></ul><ul><li>Slow cool <15°C per minute </li></ul>
    47. 47. Cosmetic Repair <ul><li>Heat treatable alloy </li></ul><ul><li>Casting is in ‘as cast’ F temper </li></ul><ul><li>Preheat and clean thoroughly </li></ul><ul><li>Use 4043 filler </li></ul><ul><li>Low heat input minimises precipitation aging </li></ul><ul><li>Post weld aging enhances weld strength – but 4043 not heat treatable </li></ul>
    48. 48. Welding Multiple Castings <ul><li>Preferably F or T2 condition </li></ul><ul><ul><li>Lowest strength in base metal </li></ul></ul><ul><li>Preheat and clean </li></ul><ul><li>Weld with 4043 or 4047 filler </li></ul><ul><li>Non heat treatable ~ slow cool </li></ul><ul><li>Heat treatable ~ Solution anneal and harden </li></ul>
    49. 49. Welding Cast to Wrought <ul><li>Same principles as casting to casting </li></ul><ul><li>Wrought material will lose strength </li></ul><ul><li>Hot weld cracking is main problem </li></ul><ul><li>Caused by shrinkage & other stresses </li></ul><ul><li>Several techniques can be used </li></ul>
    50. 50. Build-up of Castings <ul><li>Very similar to cosmetic repair procedure </li></ul><ul><li>Depends on alloy and temper </li></ul><ul><li>Preheat depends on casting size and complexity </li></ul>
    51. 51. Aluminium to Steel <ul><li>Very difficult ~ intermetallic compounds, melting temperatures, expansion </li></ul><ul><li>Can tin steel, then with tin/aluminium then use aluminium with TIG welding (used for welding anode stems to steel anode inserts) </li></ul><ul><li>Usually use friction welding (not friction stir) </li></ul>
    52. 52. Aluminium to Copper <ul><li>Used for electrical terminations </li></ul><ul><li>Can coat copper with silver or silver alloy </li></ul><ul><li>Then join with Al or Al/Si filler without penetrating the silver layer </li></ul><ul><li>Can use MIG spot welding </li></ul><ul><li>Usually use friction welding </li></ul>
    53. 53. <ul><li>Welding of aluminium castings </li></ul><ul><li>Objectives: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    54. 54. General Considerations <ul><li>Avoid unnecessary stresses </li></ul><ul><ul><li>No sudden thickness changes ~ use tapers </li></ul></ul><ul><ul><li>Ensure good fit up ~ 1 - 1,5 mm </li></ul></ul><ul><ul><li>Good alignment is essential </li></ul></ul><ul><ul><li>Use correct weld preparation ~ check drawing </li></ul></ul>
    55. 55. General Considerations <ul><li>Clean the joint properly </li></ul><ul><ul><li>Aluminium very susceptible to contamination </li></ul></ul><ul><ul><li>(hydro carbons or oxides) </li></ul></ul><ul><ul><li>Solvent wipe to degrease 50 mm either side </li></ul></ul><ul><ul><li>Clean stainless steel wire brush </li></ul></ul><ul><ul><li>Do not use grinding disks </li></ul></ul><ul><ul><li>Tungsten carbide burrs are suitable </li></ul></ul><ul><ul><li>Weld within three hours of cleaning </li></ul></ul>
    56. 56. General Considerations <ul><li>Create the right conditions for welding - physical </li></ul><ul><ul><li>Dry (RH<65%), warm, draught free conditions are best </li></ul></ul><ul><ul><li>(Be careful at coast or early on winter mornings on highveld) </li></ul></ul><ul><ul><li>Al very susceptible to hydrogen from moisture or oils – leads to porosity </li></ul></ul><ul><ul><li>Draughts can disrupt inert gas flow and cause oxide inclusions (Note - too high an inert gas flow disrupts the molten pool and causes porosity) </li></ul></ul>
    57. 57. General Considerations <ul><li>Ensure consumables are suitable </li></ul><ul><ul><li>Gas must be 99,995% pure minimum - normally Argon </li></ul></ul><ul><ul><li>Keep wire and filler rods clean and dry (remove or cover at night) </li></ul></ul><ul><ul><li>Clean using stainless steel wire wool – never use “Scotchbrite” as it leads to porosity. </li></ul></ul><ul><ul><li>No greasy gloves </li></ul></ul><ul><ul><li>Old MIG wire will become contaminated and cause oxide contamination </li></ul></ul>
    58. 58. Cutting and Preparing Al <ul><li>Cannot use oxy fuel </li></ul><ul><li>Aluminium is not fit up tolerant – cannot fill significant gaps </li></ul><ul><li>Plasma cutting widely used </li></ul><ul><ul><li>Cut surface is rough, oxidised, must be dressed </li></ul></ul><ul><ul><li>HT alloys crack 2 - 3 mm into plate ~ finish cut </li></ul></ul><ul><ul><li>Non HT alloys just need mechanical dressing </li></ul></ul><ul><li>Woodworking band saw works well </li></ul><ul><ul><li>Circular saws and portable jig saws are useful </li></ul></ul><ul><ul><li>Mineral oil lubrication is needed </li></ul></ul>
    59. 59. Cutting and Preparing Al cont.. <ul><li>Planers, routers and edge mills for edge preparation </li></ul><ul><li>Tungsten carbide burrs are suitable for final cleaning </li></ul><ul><li>Do not use (corundum) grinding disks for final cleaning </li></ul>
    60. 60. Welding problems Gas porosity in aluminium welds – always caused by hydrogen <ul><li>Low solubility in solid and high solubility in liquid aluminium </li></ul><ul><li>Alloying elements Si, Cu, Mn and Zn lower hydrogen solubility </li></ul><ul><li>Alloying elements Mg, Ni and Ti increase hydrogen solubility </li></ul><ul><li>Some hydrogen in molten metal comes from disassociation of water vapour in the air, burner fuels or damp fluxes. </li></ul><ul><li>To avoid hydrogen pick-up the oxide layer on the liquid aluminium should not be disturbed as if protects the metal. </li></ul>
    61. 61. Welding problems Gas porosity in aluminium welds – always caused by hydrogen (Low solubility in solid and high solubility in liquid aluminium)
    62. 62. Welding problems - Gas Porosity in welds
    63. 63. Welding problems Cracking in aluminium is always hot cracking <ul><li>Strength of solidifying metal is too low to resist stresses during cooling </li></ul><ul><li>Reduce heat input </li></ul><ul><ul><li>High travel speed, lowest weld parameters </li></ul></ul><ul><li>Preheat base metal ~ reduce cooling rate </li></ul><ul><li>Change joint design to minimize dilution </li></ul><ul><li>Change restraining jigs or fixtures </li></ul><ul><li>Use correct depth to width ratio </li></ul>
    64. 64. Hot Cracking cont.. <ul><li>Weld bead chemistry - Select suitable filler metal </li></ul><ul><li>Higher alloy content allows for dilution </li></ul><ul><li>Hot crack sensitivity depends on alloy content. </li></ul>Welding problems
    65. 65. Welding problems Composition relationship between filler/parent metal and weld cracking – (Note: long copper sensitivity above 0,25%) Dilution by 4043 – thus choose 5356 Dilution by 4043 – avoid 5356 5xxx 6xxx 2xxx
    66. 66. Good Fair Poor Filler Alloy 5356 Parent Alloy 6061 Filler Alloy 4043 a b d c 1 2 3 4 5 6 Silicon in the Weld Bead (%) 0 1 2 3 4 5 6 7 8 Magnesium in the Weld Bead (%) Figure 1. Resistance to hot cracking
    67. 67. <ul><li>Welding of aluminium castings </li></ul><ul><li>Topics covered: </li></ul><ul><li>What is a casting </li></ul><ul><li>Why weld a casting </li></ul><ul><li>Casting designations </li></ul><ul><li>Which castings are weldable </li></ul><ul><li>Effect of casting processes </li></ul><ul><li>Effect of welding composition </li></ul><ul><li>Alloys used in RSA </li></ul><ul><li>Welding of selected casting alloys </li></ul><ul><li>Specific applications </li></ul><ul><li>Welding problems </li></ul>
    68. 68. The welding of aluminium castings Tony Paterson (082 602 4517) Questions??
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