ENGG434 / ENG8434
Introduction to Materials Welding and Joining
TOPIC 1 – General introduction to welding technology
OUTLINE
• Background
• Need for joining technology
• Weld failures
• Why are welds potentially susceptible to
failure?
• Requirements for an acceptable weld
• Classification of joining processes
• Commonly used joining processes
• Joint configurations and welding positions
• Safety
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
BACKGROUND
• Welding continues to serve as the primary means of metal
joining in the fabrication and manufacturing industries today,
with application in fields as diverse as transport, construction,
power generation, the petrochemical industry and microelectronics.
• Welding is the most economical and efficient way of joining
metals permanently and the only way of joining two or more
pieces of metal to make them act as a single piece.
• In recent decades welding has emerged as an applied
technology with a wide, but very specialised multidisciplinary
scientific base.
• The global demand for consistently high quality welds in a
wide variety of materials continues to grow, with increasing
emphasis on basic and applied research in many weldingrelated fields.
Mining
Gas transmission
Petrochemical
Power generation
Microjoining
Power generation
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
THE NEED FOR JOINING TECHNOLOGY
• More efficient way of fabricating large or complex structures and components.
• Provides a means of performing repair and maintenance on existing structures.
• Gas or liquid tight joints can be produced.
• Completely rigid joints can be produced.
• Holes are not required for welded joints (no reduction in area).
• Gussets, filler plates and connecting angles are usually not required in welded
fabrication (overall weight reduction).
• Crevices are not formed between joint faces (fewer corrosion problems).
Welded leach autoclave
Heat
exchanger
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Reclamation of a continuous
casting roll
WELD FAILURES: Brittle fracture of
Liberty ships and T2 tankers during
World War II
Liberty Ships were the first all-welded, pre-fabricated cargo ships
built by the USA. Between 1941 and 1945, more than 2700
Liberty ships were built. During World War II, there were nearly
1500 instances of significant brittle fracture. Twelve of the
Liberty ships and T2 tankers built broke in half without warning.
“In January 1943 the one-day old T2 tanker SS Schenectady had
just completed successful sea trials and returned to harbour in
calm cool weather when … without warning and with a report
which was heard for at least a mile, the deck and sides of the
vessel fractured just aft of the bridge superstructure. The fracture
extended almost instantaneously to the turn of the bilge port and
starboard. The deck side shell, longitudinal bulkhead and bottom
girders fractured. The vessel jack-knifed and the centre portion
rose so that no water entered. The bow and stern settled into the
silt of the river bottom.”
Journal of the American Society of Naval Engineers, vol. 55(2), May 1943, 358-361.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELD FAILURES: Brittle
fracture of Liberty ships and T2
tankers during World War II
• Brittle fractures often initiated at upper
deck covers and almost always at the
welds.
• Almost all failures occurred in winter.
• The steel’s ductile-to-brittle transition was
above ambient temperature. Failure was
caused by low weld notch toughness at
low temperatures, with cracks initiating at
weld defects or stress concentration
points.
• Unlike riveted hulls there were no natural
crack arrestors (rivet holes or plate edges)
to halt propagation of the cracks.
Crack
Rivet
hole
Weld
Crack
WELDED
CONSTRUCTION
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
RIVETED
CONSTRUCTION
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
WELD FAILURES: King Street
Bridge, Melbourne
• The King Street Bridge over the Yarra River in Melbourne
was an all-welded steel girder structure, built between 1957
to 1961 using 30 m long fabricated I-beams, reinforced with
cover plates on the lower tension flange to save material.
• On the morning of 10 July 1962, three of the four girders
fractured in a brittle manner at points 4.9 m from both the
southern and northern ends, whereas the fourth girder failed
at only one position (southern end).
• Failure occurred under a load of 470 kN (47 tons), which was
well within the permissible design limits for the bridge. The
roadway dropped by 300 mm under the weight of a 28 ton
truck.
• Cracking started from weld heat-affected zones at the ends of
the cover plates.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELD FAILURES: King Street
Bridge, Melbourne
The failure of the four girders was attributed to a
combination of three factors: inappropriate steel for
welding, unsatisfactory design details, and low ambient
temperatures.
The King Street bridge today
• The bridge was constructed using a fairly new steel specification
introduced by British Steel - BS 968, a high-carbon, high-strength
steel designed for riveted and bolted bridge construction. Welding
of such a high-carbon steel promotes heat-affected zone failures.
• Low notch ductility - the temperature at the time of failure (10°C) was well below the ductile-to-brittle transition temperature
of the steel.
• Lack of preheating in the short transverse welds at the ends of the
cover plates which terminated at the position of fracture.
• The thickening of the flanges at points of maximum tensile stress
by the addition of cover plates constituted poor design.
• Poor weld sequence and electrode care.
The 1963 report
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
WHY ARE WELDS POTENTIALLY SUSCEPTIBLE
TO FAILURE?
Welding results in:
•
•
•
•
Geometric discontinuities
Microstructural changes in the vicinity of the weld
Residual stress
Weld defects
Weld failure in the main
tower of a wind turbine
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
WELDING RESULTS IN GEOMETRIC
DISCONTINUITIES:
Change in cross-section results in stress
concentration
Geometric discontinuities and changes in
section thickness result in stress
concentrations → preferential crack
initiation sites.
Stress corrosion cracking from the weld
toe of a stainless steel weld
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELDING RESULTS IN GEOMETRIC
DISCONTINUITIES:
Tendency towards failure is enhanced by poor
weld profile, misalignment, weld toe
intrusions and undercut.
Hydrogen crack from the weld toe of a
carbon steel weld
Poor weld
profile
Undercut
Misalignment
Hydrogen crack from the root of a
carbon steel weld
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELDING RESULTS IN CHANGES IN MICROSTRUCTURE:
Welding can affect:
•
•
•
•
•
•
Base metal
Weld metal
Base metal
Grain structure
Grain size
Phase composition
Segregation
Recrystallisation
Precipitates and
inclusions
Weld metal
Weld
Base metal
STRUCTURE – PROPERTY RELATIONSHIP
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
WELDING RESULTS IN CHANGES IN MICROSTRUCTURE:
Laser welding of semi-solid metal processed rheocast aluminium
alloy AA7017 (Al-Mg-Zn):
Base metal
Al-rich matrix
(Al,Zn)49Mg32
Weld metal
M. du Toit, P.R. Letsoalo and H. Möller. “Fusion welding of rheocast semisolid metal (SSM) processed aluminium alloy 7017”. Solid State Phenomena.
Precipitation of fine, uniformly distributed
(Al,Zn)49Mg32 precipitates in the weld
metal increased hardness and strength of
the weld.
13
Hardness profile across an autogenous
laser weld
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELDING RESULTS IN RESIDUAL STRESS:
Welding creates high tensile residual
stresses in the weld and adjacent heataffected zone. In carbon steels, these
residual stresses approach the yield
stress of the material.
Residual stress measurements in a steel weld using
neutron diffraction techniques
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
WELDING MAY RESULT IN WELD DEFECTS:
Slag inclusion
Lack of fusion
Centreline crack
Porosity
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
REQUIREMENTS FOR AN ACCEPTABLE WELD
2. Energy source / process
3. Filler metal / consumable
1. Base metal preparation
Joint preparation
Clean
Fit-up
4. Protection from atmospheric
contamination
Flux/slag
Shielding gas
Vacuum
5. Skilled welding personnel
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
QUALIFIED WELD PROCEDURE
SPECIFICATION (WPS)
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
ENERGY SOURCES
AND WELDING
PROCESSES
USING AN ELECTRIC ARC AS ENERGY SOURCE:
An arc is defined as electric current flowing between two electrodes
through a column of ionised gas (plasma).
Plasma Arc Welding
Gas Metal Arc Welding
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Temperature distribution in a low
current gas tungsten arc
A welding transformer is a step-down transformer. The
voltage relationship between the primary and secondary
coils is determined by the number of turns in each coil.
NP/NS = VP/VS
where: N is the number of turns, V is the induced voltage,
and the subscripts P and S refer to the primary and
secondary coils, respectively.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
How NOT to do it!
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Some newer developments:
• Inverter technology
• Synergic Power Supplies
• Waveform Control
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Waveform
control
Filler wire
Shielding gas
Conventional short-circuiting
transfer in Gas Metal Arc
Welding (GMAW):
Spatter
Arc instability
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Lincoln Electric Surface Tension Transfer (STT) process:
Controlled shortcircuiting (dip)
transfer:
Waveform Control
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
• Reduced spatter
• Reduced fume
• Heat input control
Gas Tungsten Arc Welding (GTAW) – Arc heating
Gas Tungsten Arc Welding
An arc welding process in which
the heat for welding is supplied by
an arc that forms between the
workpiece and a non-consumable
tungsten electrode. The electrode,
weld pool, arc and adjacent base
metal are protected from
atmospheric contamination by a
gaseous shield.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Gas Tungsten Arc Welding (GTAW) – Arc heating
• Very clean and defect-free process, suitable for producing high quality welds.
• Very thin base metals (fraction of a mm) can be joined.
• GTAW is suitable for welding most metals and alloys (even reactive metals such as Ti).
• Manual welding requires a great deal of skill.
• Poor shielding can result in contamination of the weld metal.
• Tungsten particles in the arc can form of inclusions in the weld.
• GTAW is uneconomical for joining thick sections.
• Slow welding speeds, low deposition rates & low melting rates.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Plasma Arc Welding (PAW) – Arc heating
Non-consumable
tungsten electrode
Plasma gas
Shielding gas
Constricting nozzle
Constricted
arc
Plasma arc welding (PAW) is a gas-shielded arc welding process that uses an electric arc
that forms between a non-consumable tungsten electrode and the workpiece to heat and
melt the substrate. The PAW process therefore has many features in common with gas
tungsten arc welding (GTAW), but differs from the GTAW process in that the arc plasma
is constricted by a nozzle orifice to form a highly focused, intense welding arc.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Manual Metal Arc Welding (MMAW) – Arc heating
Core wire
Flux covering
Electrode holder
Evolved gas shield
Arc
Slag
Weld metal
Manual metal arc welding is an arc welding
process in which the heat for welding is supplied
by an arc that forms between the workpiece and a
short, consumable flux-coated electrode.
Shielding is provided by a covering of molten
flux (slag) over the weld pool, and by evolution
of gas from the electrode coating.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Submerged Arc Welding (SAW) – Arc heating
Wire feeder
Flux delivery tube
Electrode wire
Granular flux
Slag
Arc cavity
Solidified weld
Arc
Submerged arc welding is an arc welding process in which the heat for welding is supplied by
an arc that forms between the workpiece and a bare consumable electrode wire that is fed
continuously into the weld pool. The weld pool, arc, electrode and adjacent base metal are
protected from atmospheric contamination by a thick blanket of granular flux that melts in
contact with the liquid weld metal to form a thin layer of slag.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Gas Metal Arc Welding (GMAW) – Arc heating
Gas metal arc welding is an arc welding process in which the heat for welding is
supplied by an arc that forms between the workpiece and a bare solid consumable
electrode wire. The weld pool, arc, wire electrode and adjacent base metal are
protected from the atmosphere by a shielding gas that flows through the torch.
Gas Metal Arc Welding
Metal transfer across the arc during Gas
Metal Arc Welding
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Flux Cored Arc Welding (FCAW) – Arc heating
FCAW-G (Auxiliary shielding gas)
FCAW-G (Self-shielded)
Flux cored arc welding is an arc welding process in which the heat for welding is
supplied by an arc that forms between the workpiece and a tubular consumable
electrode wire. The weld pool, arc, electrode wire and adjacent base metal are protected
from atmospheric contamination by a thin slag covering and by gas evolved during the
combustion and decomposition of flux compounds contained within the tubular
electrode wire, with or without the use of additional external shielding gas.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
USING ELECTRICAL RESISTANCE AS HEAT SOURCE FOR
WELDING:
Resistance spot
welding (RSW)
Heat generated = I 2 Rt
where: I is the welding current
R is the resistance
t is time
5000 to 20,000 A
Resistance spot welding) is a resistance welding process
used primarily for welding two or more metal sheets
together by applying pressure and heat from an electric
current to the weld area.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Resistance spot welding – Pressure welding process
RSW weld nugget
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Electroslag Welding (electrical resistance heating):
Electroslag Welding (ESW) utilises the heat generated by the resistance heating effect
produced by passing a high current through a molten slag bath. A consumable filler wire
conducts the current into the bath and continuously melts to form the weld metal.
Wire
Guide
Slag pool
Metal droplets
Run-off tab
Consumable guide and
wire submerged in flux
Wire submerged in flux
Weld pool
Weld
Sump
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Electroslag Welding (electrical resistance heating):
Electrode
wires
Run-off tab
Slag
Retaining
shoes
Vertical base
metal plates
Sump
Starting plate
Weld metal
Run-on tab
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
USING RADIATION ENERGY AS HEAT SOURCE FOR WELDING:
Laser welding or laser beam welding (LBW)
uses a moving high density (105 to 107
W/cm2) coherent laser beam as heat source
for welding. For welding, the laser must be
focused to a small spot size to produce a high
power density. This controlled power density
melts the metal, and in the case of deep
penetration welds, vapourises some of it.
2 mm
Cross-section of
a laser keyhole
weld
Laser cladding
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Laser Hybrid Welding
Laser
Wire
Laser hybrid welding refers to a combination of
high power laser welding with conventional arc
welding, with both processes acting
simultaneously in the same weld pool.
Improved tolerance to joint fit-up.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Electron Beam Welding (EBW) – Power beam process
EBW vacuum chamber
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
USING A CHEMICAL REACTION AS HEAT SOURCE FOR WELDING:
Oxy-Acetylene Gas Welding
Combustion of acetylene in oxygen
can produce a flame temperature of
3100°C to 3300°C.
2C2H2 + 5O2 → 4CO2 + 2H2O
Oxy-fuel gas welding is a manual process in which
the metal surfaces to be joined are melted by heat
from a gas flame, with or without the addition of
filler metal, and are caused to flow together and
solidify without the application of pressure to the
parts being joined.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Aluminothermic (Thermit) welding (chemical heat source):
A welding process that employs an exothermic reaction to heat the metal, and requires no
external source of heat or current.
3Fe3O4 + 8Al → 4Al203 + 9Fe (+ 3350 kJ)
(Temperature > 3000°C)
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Aluminothermic
(Thermit) welding
Crucible
Molten slag
Molten metal
Tapping device
Slag basin
Risers
Sand/refractory mould
Rail
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
USING PRESSURE AND/OR DEFORMATION AS ENERGY SOURCE
FOR WELDING:
Friction welding is a solid-state welding
technique that uses friction to soften the
contact surfaces at the joint interface before
applying pressure to join the parts.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
Friction welding
Cross-sections of a friction welds
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Friction Stir Welding – Deformation welding process
Structure of a typical friction stir weld
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Cold Pressure Welding – Pressure welding process
Cold pressure welding is a solid state
welding process, in which two work
pieces are joined together at room
temperature and under a pressure, causing
a substantial deformation of the welded
parts and providing an intimate contact
between the welded surfaces.
Roll bonded
aluminium
refrigerator
evaporation plate
Roll bonding
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Explosive welding – Deformation welding process
1
2
3
4
5
6
Wavy interface characteristic of explosive welding
Flyer (cladding)
Resolidified zone
Target (substrate)
Explosion
Explosive powder
Plasma jet
Explosive Welding is a solid-state
welding process, in which welded parts
(plates) are metallurgically bonded as a
result of oblique impact pressure exerted
by the controlled detonation of an
explosive charge.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Flash Butt Welding
Flash butt welding of anchor chains
Flash Butt Welding is a resistance welding
process, in which ends of rods (tubes, sheets) are
heated and fused by an arc struck between them
and then forged (brought into a contact under a
pressure) producing a weld.
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Flash butt welding of rails
WELDING PROCESS
CLASSIFICATION
CLASSIFICATION OF JOINING PROCESSES
AWS A3.0M/A3.0
Above the melting
temperatures of the
filler metal and the
material being
joined
Below the melting
temperature of the
joint and the base
metal
Between the melting
temperatures of the
braze alloy/solder and
the material being
joined
Welding classification based on the type of interaction
during joining:
Welding process class
Type of interaction
Fusion welding
liquid / liquid
Solid-state welding
solid / solid
Brazing and soldering
solid / liquid
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
MECHANICAL JOINING
Joining technologies in which the parts are joined
using a force or form-locking method such as bolting,
screwing or riveting. The joint strength is determined
by the strength of the bolt/screw/rivet and frictional
forces.
√
√
√
√
Site assembly
Temporary
Low skill?
Low cost?
×
×
×
×
Preparation
Discontinuity
Corrosion
Weight
Bolted construction
New techniques include self piercing rivets, press
joining and hybrid joining techniques with
adhesives.
Riveted construction
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
ADHESIVE BONDING
Adhesive bonding is a wafer bonding technique
involving the application of an intermediate layer to
connect substrates using any number of adhesive
substances. Paste, glue, and tape are examples of
common adhesives.
√ Wide range of materials
√
√
√
√
Dissimilar materials
Multiple joints
Simple
Little damage to parent material
×
×
×
×
×
×
×
Cleaning
Safety
Curing time
Adhesive bonding
Strength?
Temperature range
Non-destructive evaluation difficult
Lap joints require more material (weight)
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
BRAZING AND SOLDERING
Brazing is a joining process whereby a filler metal is heated above its melting point and
distributed between two close-fitting parts by capillary action. The filler metal is brought
on capillary
jointby
filling
slightly above its melting Relies
temperature
while protected
a suitable atmosphere, usually
a flux. (Temperature between 450°C and the melting point of the metal being joined).
Soldering is a process in which two or more parts are joined together by melting and
flowing a filler metal (solder) into the joint. The filler metal has a lower melting point
than the adjoining metal. (Temperature less than 450°C).
√ Low melting point filler
√
√
√
√
Simple
Dissimilar materials
Low thermal damage
Microjoining
×
×
×
×
×
Cleaning
Capillary gap
Temperature limit
Strength
Safety?
Soldering
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
FUSION WELDING
• A union between two pieces of metal rendered plastic or liquid by heat or pressure or
both. A filler metal with a melting temperature of the same order of that of the parent
metal may or may not be used.
• A localised coalescence of metals or non-metals produced either by heating the materials
to the welding temperature, with or without the application of pressure, or by the
application of pressure alone, with or without the use of a filler metals.
√ Matching strength
√ Continuous seams
√ Temperature resistant
√ Lightweight
×
×
×
×
Cost
Quality
Safety
Permanent
Metal transfer across the arc in
gas metal arc welding
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Classification of fusion welding processes:
The nature of the energy source during welding
Electrical
Thermo-chemical
The heat source during welding
Electric arc
Electrical resistance
Radiation
Induction/conduction
Application of mechanical energy
Pressure
Deformation
Pressure or deformation
Major shielding mechanism
Flux or slag
Gas
Combination of flux or gas
Vacuum
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
CLASSIFICATION OF FUSION WELDING PROCESSES
54
Process classification in
accordance with AS 2812
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
BASIC JOINT CONFIGURATIONS
Butt (groove) weld
Fillet weld
Lap weld
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
BUTT WELDS
Single-square groove weld
Double-square groove weld
Single-V groove weld
Single-V groove weld with backing
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Double-V groove weld
Narrow gap
BUTT WELDS
Single-bevel groove weld
Double-bevel groove weld
Single-J groove weld
Double-J groove weld
Single-U groove weld
Double-U groove weld
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
BUTT WELDS
Terminology:
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
OTHER JOINT TYPES
Arc spot weld
Arc spot welds
Edge flange weld
Stake weld
Edge weld
Plug welds
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
Twin fillet
PARTS OF A WELD AND JOINT SIZES
Butt welds
Fillet welds
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
1.1 GENERAL INTRODUCTION TO WELDING TECHNOLOGY
WELDING POSITIONS
ISO 6947:2010
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELDING POSITIONS
ISO 6947:2010
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELDING POSITIONS
AWS A3.0M/A3.0
F: FILLET WELD
G: GROOVE (BUTT) WELD
Flat (or downhand):
Horizontal:
Vertical up or down:
Overhead:
Positional fixed pipe welding:
1G or 1F
2G or 2F
3G or 3F
4F or 4G
5G, 5F & 6G (inclined pipe)
Overhead welding
(If the workpiece is rotated, the suffix R is added)
Vertical welding
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology
WELD SAFETY
•
•
•
•
•
•
Compressed gas
Fume
Noise
Mechanical hazards
Fire and burns
Radiation (visible, UV, IR,
X-ray)
• Electric shock
ENGG434/ENG8434 – TOPIC 1: General introduction to welding technology