5/13/2010

1

Weld Inspection

Level 1

Introduction to Welding

Definition

Introduction to Welding

Welding Terminology

Physics of Welding

5/13/2010

2

DefinitionWelding: A group of processes used to join metallic and

nonmetallic materials. Often done using heat but maybe

done using pressure or a combination of heat and pressure.

A filler material may or may not be used.

Other processes: riveting, forging, cutting, turning, and bending

First used: 2000 BC

Modern methods: 1881

Examples of Welding Processes

Shielded Metal Arc

Gas Tungsten Arc Welding

Gas Metal Arc Welding

Submerged Arc Welding

5/13/2010

3

Shielded Metal Arc Welding

Gas Tungsten Arc Welding

5/13/2010

4

Gas Metal Arc Welding

Submerged Arc Welding

5/13/2010

5

Introduction to Welding

Joint between the materials is melted

Intermixing occurs

Upon solidification a metallurgical bond results

The weld has the potential to have same strength as the

materials being joined

Unlike soldering, brazing and adhesive bonds which are

not fusion processes

Arc Welding

Intense heat to melt metal is produced by electric arc

Arc between electrode and metal to be joined

5/13/2010

6

Shielded Metal Arc Welding

High current, low voltage, AC or DC

The Arc

5/13/2010

7

Heat in The Arc

Change the arc length

Change the shielding gas

Addition of potassium salts reduces arc voltage

Metal Arc Transfer

Metal is transferred across the arc (consumable electrode)

Mechanism of transfer:

Molten metal drop touches and transfers by

surface tension

Magnetic pinch effect

Gravity (flat welding)

More heat is transferred than non-consumable electrodes

Ionization column must be present to conduct electricity (arc)

5/13/2010

8

Electrical Supply

AC

DC, electrode positive

DC, electrode negative

Selection depends upon:

Process

Type of electrode

Arc atmosphere

Metal being welded

Properties of Metals

Physical

Chemical

Mechanical

5/13/2010

9

Physical Properties

Colour

Melting Temperature

Density (weight per unit volume)

Chemical Properties

How the metal reacts in an environment

Corrosion Resistance (ability to resist corrosion)

Oxidation Resistance (ability to resist combining with oxygen)

5/13/2010

10

Mechanical PropertiesStrength (ability to resist load without failing)

Tensile strength (ability to resist pulling force)

Compressive strength (ability to resist crushing force)

Ductility (ability to deform without breaking)

Brittleness (inability to resist fracture)

Toughness (ability to resist cracking)

Hardness (ability to resist indent or scratching)

Grain size (important in determining mechanical properties)

Effects of Welding

Heat creates stress, affects ductility and toughness

Effects of previous heat treating are lost around the weld

If done properly usually stronger than the base metal

Can effect the chemical resistance

5/13/2010

11

Expansion and Contraction

Metal expands when heated

Metal contracts when cooled

Expansion and contraction creates stress

Welding jigs or fixtures prevent movement but lock in stress

Butt Joint Root Opening

5/13/2010

12

Butt Joint Root Opening

Butt Joint Distortion

5/13/2010

13

Tee Joint Distortion

Reducing Distortion & Stress

Tack weld

Align parts for contraction

Use jigs or fixtures

Preheat parts

Heat treat welded parts

Proper welding procedures

5/13/2010

14

Heat Treating

Pre heating

Raise the temperature just prior to welding

Entire part is heated

Less contraction and stress on cooling

Heat Treating

Interpass heating

Heating while welding or between passes

Minimize expansion and contraction

Reduce stress

5/13/2010

15

Heat Treating

Annealing

Heat treatment after welding

Heated above critical temperature

900° C for mild steel

Held at temperature for 1 hour per inch of thickness

Slow cooled

Heat Treating

Stress Relieving

Heat treatment after welding

Heated below transition temperature

650° C for mild steel

Held at temperature for 1 hour per inch of thickness

Air cooled

Relieves some of the stress of welding

5/13/2010

16

Electrical Principles

Voltage

Force that causes electrons to flow in a circuit

Similar to pressure

Measured in volts

Electrical Principles

Resistance

Opposition to flow of electrons measured in ohms

Air gap is resistance

If voltage is not sufficient to overcome resistance

of gap no arc exists

Higher voltage allows a longer arc

Arc stops if voltage is not high enough

5/13/2010

17

Electrical Principles

Current

Flow of electrons measured in amperes

Compared to flow of water

If there is no arc, no current flows in welding circuit

Units of Measure

Micro [µ] = 1/1,000,000 or .000001

Milli [m] = 1/1,000 or .001

Centi [c] = 1/100 or .01

Deci [d] = 1/10 or .1

Kilo [ K] = 1,000

Mega [M] = 1,000,000

5/13/2010

18

Terminology

Welding Technology Fundamentals

Page 441

Procedures Handbook of Arc Welding

Page 16.1-1

Basic Weld Joints

5/13/2010

19

Butt Joints

Parts of a Grooved Butt Joint

5/13/2010

20

Corner Joint

T - Joint

5/13/2010

21

Edge Joint

Fillet Welds

5/13/2010

22

Engineering Drawings

Isometric Projection

5/13/2010

23

Orthographic Projection

Orthographic Projection

5/13/2010

24

Orthographic Projection

Orthographic Projection

5/13/2010

25

Orthographic Projection

View Selection

5/13/2010

26

First and Third Angle

Projection

First and Third Angle

Projection

5/13/2010

27

Drawing Lines

Dimensioning

S = size

P = position

5/13/2010

28

DimensioningAngles Chamfers

Tapers

Auxiliary Views

5/13/2010

29

Sectional Views

Sectional Views

Mating parts

Typical cross section

5/13/2010

30

Thread Illustrations

Team Project 2

Prepare a sketch in third angle orthographic projection

5/13/2010

31

Preparation of Joints for

Welding

Preparation of Joints for

Welding

Flanged Preparation

e = member thickness

Used of relatively thin material

Medium efficiency

5/13/2010

32

Preparation of Joints for

Welding

Square Butt Preparation with backing

g = root gap

Improves probability or full penetration

Stress raisers that affect fatigue performance

Preparation of Joints for

WeldingSingle Vee Preparation

ß = bevel angle, α = groove angle, s = root face,

g = root gap, = solid angle

Optimum joint efficiency require back gouging and

welding

5/13/2010

33

Preparation of Joints for

Welding

Single Bevel Preparation

α = groove angle, s = root face, g = root gap,

Ω = angle of incidence

Used for Tee and corner joints

Optimum joint efficiency require back gouging and

welding

Preparation of Joints for

Welding

Single U Preparation

α = groove angle, s = root face, g = root gap,

β = bevel angle, r = root radius

Reduced volume of weld as compared to Vee,

less distortion

Optimum joint efficiency require back gouging and

welding

5/13/2010

34

Preparation of Joints for

WeldingPartial U Preparation

α = groove angle, s = root face, g = root gap,

d = depth of prepared edge, r = root radius,

b = root width

Preparation of Joints for

WeldingDouble Vee Preparation

α = groove angle, s = root face, g = root gap,

β = bevel angle, d = depth of of prepared edge

Reduced distortion and weld volume compared to

single Vee, back gouging preferred before

welding second side

5/13/2010

35

Preparation of Joints for

WeldingDouble Vee Preparation with Broad Root Face

α = groove angle, s = root face, g = root gap,

d = depth of prepared edge

Used in SAW

Preparation of Joints for

WeldingDouble U Preparation

α = groove angle, s = root face, g = root gap,

β = bevel angle, d = depth of of prepared edge

Used for thicker sections

Reduced volume of weld as compared to Vee,

less distortion

5/13/2010

36

Preparation of Joints for

WeldingDouble J Preparation

α = groove angle, s = root face, g = root gap,

d = depth of prepared edge, r = root radius

Preparation of Joints for

WeldingPartial Double J Preparation

α = groove angle, s = root face, g = root gap,

r = root radius, d = depth of of prepared edge

5/13/2010

37

Preparation of Joints for

WeldingMixed Preparation

α = groove angle, r = root radius, l = half width of flat bottom

Welding Symbols

5/13/2010

38

Welding Symbols

L-P

FAR

S (E)T

N

L-P

FAR

S (E)T

N

Weld-all around

5/13/2010

39

L-P

FAR

S (E)T

N

Field Weld

L-P

FAR

S (E)T

N

Reference Line

5/13/2010

40

L-P

FAR

S (E)T

N

Tail(Tail omitted when references not used)

L-P

FAR

S (E)T

N

Specification, process or other reference

5/13/2010

41

L-P

FAR

S (E)T

N

Depth of penetration, size or strength

L-P

FAR

S (E)T

N

Groove weld size

5/13/2010

42

L-P

FAR

S (E)T

N

Basic weld symbols

L-P

FAR

S (E)T

N

Finish symbol

5/13/2010

43

L-P

FAR

S (E)T

N

Finish contour

L-P

FAR

S (E)T

N

Groove angle

5/13/2010

44

L-P

FAR

S (E)T

N

Root opening

L-P

FAR

S (E)T

N

Number of spot, stud or projection welds

5/13/2010

45

L-P

FAR

S (E)T

N

Length and pitch

Basic Weld Symbols

L-P

FAR

S (E)T

N

Designates the specific type of weld

5/13/2010

46

Basic Groove Weld Symbols

Square

Single V

Single bevel

Double J

Double flare

Fillet and Plug Weld Symbols

Fillet

Plug

5/13/2010

47

Single and Double Welds

Single Double

Bevel Groove

J Groove

Flare

Fillet

Arrow Significance

5/13/2010

48

Arrow Significance Groove

Welds

Arrow Significance Groove

Welds

5/13/2010

49

Arrow Significance Fillet

Welds

Arrow Significance Fillet

Welds

5/13/2010

50

Information in the Tail

L-P

FAR

S (E)T

N

Specification, process or other referenceWelding process

Welding procedure

“Typical” representative of all welds on the drawing

Field Weld

In a place other than original construction

Usually in the erection phase

5/13/2010

51

Melt-thru Symbol

Extent of Welding

If length is not specified

length is between abrupt changes in direction

Length maybe directly dimensioned on drawing

Weld all around symbol

L-P

FAR

S (E)T

N

Weld-all around

5/13/2010

52

Uses of Weld All Around

Finishing of Weld

C Chipping

G Grinding

M Machining

R Rolling

H Hammering

5/13/2010

53

Break in Arrow

Arrow points to member to be chamfered

Combined Welding Symbols

5/13/2010

54

Alternate Combined Welding

Symbols (AWS A2.4)

Complete Penetration

Note: CJP = Complete joint penetration

or CP = Complete penetration

GTSM = Grind to sound metal

5/13/2010

55

Groove Welds

Key parameters:

Depth of penetration

Bevel angle

Root opening

Three Basic Angles

Θ1 = Bevel angle

Θ2 = Groove angle

Θ3 = Angle at root

5/13/2010

56

Dimensioning Double Groove

Welds

Depth of Penetration &

Groove Weld Size

L-P

FAR

S (E)T

N

L-P

FAR

S (E)T

N

5/13/2010

57

Depth of Penetration &

Groove Weld Size

E may be greater or smaller than S

Practice

Single Groove

Partial Penetration

5/13/2010

58

Practice

Single Groove

Partial Penetration

Practice

Single Groove

Partial Penetration

5/13/2010

59

Practice

Single Groove

Partial Penetration

Practice

Double Groove

Partial Penetration

5/13/2010

60

Practice

Double Groove

Partial Penetration

Practice

Double Groove

Partial Penetration

5/13/2010

61

Practice

Double Groove

Partial Penetration

Practice

Double Groove

Full Penetration

5/13/2010

62

Practice

Double Groove

Full Penetration

Practice

Double Groove

Full Penetration

5/13/2010

63

Practice

Square Groove

Square Groove

Requires Full Penetration

5/13/2010

64

Square Groove

Symmetrical Double Groove

Welds

5/13/2010

65

Optional Joint Preparation

Complete Penetration With

Back-gouging

5/13/2010

66

Complete Penetration With

Back-gouging

Complete Penetration With

Back-gouging

5/13/2010

67

Flare Weld

Flare Weld

5/13/2010

68

Surface Finish

Most common is flush

Welds With Backing

Basic Symbol

M = Material of backing bar

R = Removal of backing bar after

welding

5/13/2010

69

Welds With Backing

Backing bar size can be placed in tail

S = SteelR = Removed

Joints With Spacers

5/13/2010

70

Combination Groove and Fillet

Sequence of Preparation

Solid lines indicate preparation before fit-up

5/13/2010

71

Sequence of Preparation

Solid lines indicate preparation before fitting

CSA W59

Fillet Welds

5/13/2010

72

Fillet Welds

Note: vertical side (line) always on left

Equal-legged

Fillets

5/13/2010

73

Fillet Size

S = Specified size (size on symbol)

Seff = Effective size (size that corresponds to

specified size)

Sm = Measured size (based on actual measurement)

Fillet Size

5/13/2010

74

Fillet Size

Some countries specify the size of fillet by throat

rather than leg

In Canada and USA we use leg

ISO (ISO/TC44/SC7) recognizes both, but requires

identification:

“z” designates leg size

“a” designates throat size

Fillet Size

5/13/2010

75

Unequal-legged Fillet Welds

Size is shown in brackets as:

(S1 x S2)

Not leg specific

Unequal-legged Fillet Welds

or

5/13/2010

76

Unequal-legged Fillet Welds

Often the which leg size is governed by

geometry of joint

Fillet Sizes (With Gaps)

Gaps less than 1mm (CSA W59)

or 1/16 (AWS D1.1)

5/13/2010

77

Fillet Sizes (With Gaps)

Gaps greater than 1mm (CSA W59)

or 1/16 (AWS D1.1)

Maximum gap

5mm for material < 75mm thick

8mm for material > 75mm thick

Measured size increased

by amount of gap

Fillet Welds in Skewed

Connections

Beyond this range, weld is considered partial

penetration (CSA W59 and AWS D1.1)

5/13/2010

78

Fillet Welds in Skewed

Connections

It is necessary to show a sketch of the weld with

dimensions

Length of Fillet Welds

5/13/2010

79

Length of Fillet Welds

Length of Fillet Welds

(Not Specified)

Considered to run length of joint to change of

direction

5/13/2010

80

Length of Fillet Welds

(Not Specified)

Fillet

All-around

5/13/2010

81

Intermittent Fillet Welds

Intermittent Fillet Welds

Common Centre Symbols Aligned

5/13/2010

82

Intermittent Fillet Welds

Staggered Centres Staggered Symbols

Fillets Welds

With Terminal Ends

5/13/2010

83

Fillets Welds

Surface Finish & Contour

Plug and Slot Welds

5/13/2010

84

Plug and Slot Welds

Plug and Slot Welds

5/13/2010

85

Plug Welds

Key Parameters:

Diameter of hole

Angle of countersink

Depth of filling

Spacing of welds

Contour and surface finish

Plug Weld, Diameter

5/13/2010

86

Plug Weld, Countersink

Plug Weld, Depth of Filling

Complete fill

5/13/2010

87

Plug Weld, Spacing

Plug Weld, Symbols

5/13/2010

88

Safety Considerations

Pressurized Gases

High temperatures and hot surfaces

Electrical hazards

Fume generation

Non-ionizing radiation

Ionizing radiation

Molten droplets of metal

Explosive hazards

Oxy-Fuel Cutting

Torch tip selection

Oxygen pressure

Acetylene pressure

Cutting Speed

Tip alignment

Torch Position

5/13/2010

89

5/13/2010

90

Tip Alignment

Torch Position

Tilted to 20 degrees away from direction of cutting

5/13/2010

91

Torch Position

Torch 90 degrees to the surface of the metal

Torch Position

Cutting thin steel

5/13/2010

92

Cutting Conditions

Good Cut

Cutting Conditions

Preheat flames too small

Cutting speed too slow

5/13/2010

93

Cutting Conditions

Preheat flame too long

Top surface melted over

Cutting edge irregular

Excess slag

Cutting Conditions

Oxygen pressure too low

Top edge melted

Travel speed too slow

5/13/2010

94

Cutting Conditions

Oxygen pressure too high

Nozzle too small

Cut control lost

Cutting Conditions

Cutting speed too slow

Irregular, emphasized drag lines

5/13/2010

95

Cutting Conditions

Cutting speed too fast

Pronounced break in drag line

Cut edge irregular

Cutting Conditions

Torch travel unsteady

Cut edge wavy and irregular

5/13/2010

96

Cutting Conditions

Cut lost

Not properly restarted

Bad gouges at restart point

Shielded Metal Arc Welding

5/13/2010

97

Shielded Metal Arc Welding

Acronyms:

AC Alternating Current

DC Direct Current

CC Constant Current

CV Constant Voltage

DCEN Direct Current Electrode Negative

DCEP Direct Current Electrode Positive

OCV Open Circuit Voltage

Current and Polarity

DCEN DCEP

5/13/2010

98

Current and Polarity

DCEP Deeper penetration than DCEN

DCEN Electrode melts faster, less heat to the

base metal

Used for welding thin materials

AC Produce a neutral or reducing gas

(to protect the weld puddle)

Medium depth of penetration

Current and Polarity

Manual processes such as SMAW require CC welding

machine

CC machines sometimes called droopers or droop curve

machines

A CC machine adjusts to maintain a constant current as

small changes in arc length occur

5/13/2010

99

Constant Current Machine

25% change in voltage 4% change in current

Welding Machines

5/13/2010

100

Welding Machines

Current Type (AC, DC, or AC/DC)

Input power requirements (117, 240 0r 550 Volts)

Rated current output

Duty Cycle

Open Circuit Voltage

Rated Current Output

5/13/2010

101

Duty Cycle

How long a welding machine can be used at maximum

current

Based on a ten minute cycle

E.g. 60% duty cycle machine can be used at maximum current

for a maximum of 6 minutes out of every 10 minutes.

It can be used for longer periods at lower current settings

Duty Cycle

200 amp, 20% duty cycle

5/13/2010

102

Open Circuit Voltage

Voltage of the welding machine when on but not being used.

Typically 80 volts compared to closed circuit voltage of

5 to 30 volts

A high OCV is required to initiate the arc.

Welding Leads

Electrode lead

Work lead

Electrical resistance increases as diameter decreases

and length increases

Voltage and current are affected when leads are too small

in diameter

5/13/2010

103

Welding Leads

Welding Technology Fundamentals

Page 58

Wire Diameter

Suggested Filter Lenses

Sensible 7 thru 14 Shade

Adjustability On The Outside

Of The Helmet While You Are

Welding

5/13/2010

104

SMAW ElectrodesSpecified by:

AWS

A5.1 carbon steel

A5.3 aluminum and aluminum alloys

A5.4 corrosion resistant steels

A5.5 low alloy steels

A5.6 copper and copper alloys

A5.11 nickel and nickel alloys

A5.15 gray and ductile cast iron

CSA W 48-01

carbon steel covered electrodes

chromium and chromium-nickel covered electrodes

low alloy steel covered electrodes

Electrode Coverings

1. Add filler metal

2. Create a protective gas shield

3. Create a flux to remove impurities

4. Create slag to protect bead as it cools

5. Add alloys to improve mechanical and chemical properties

6. Determine the polarity of electrode

5/13/2010

105

Electrode Size

CSA W47-01

Electrode Size

AWS

Lengths: 9, 12, 14, and 18 inches

Diameters: 1/16, 5/64, 3/32, 1/8, 5/32, 3/16, 7/32,

1/4, 5/16, 3/8 inches

5/13/2010

106

Freezing Characteristics

Electrodes manufactured to melt rapidly are called

fast-fill electrodes

Electrodes manufactured to freeze rapidly are called

fast-freeze electrodes

Electrodes manufactured to compromise between

fast-fill and fast-freeze are called fill-freeze

Electrode Designations

E 6010

AWS

Electrode

Minimum tensile strength in thousand psi

Welding position

Utilization

5/13/2010

107

Minimum Tensile strength

Minimum tensile strength of the as deposited metal

Welding Position

1 All position

2 Flat and horizontal fillets only

3 Flat position only

4 Flat, horizontal, overhead and vertical down

5/13/2010

108

Team Assignment 5

Assignment

What electrodes are low hydrogen?

What electrodes cannot be used with AC?

Which electrodes have iron powder addition?

Cellulose is used to improve penetration, what

electrodes will provide good root penetration?

What electrodes cannot be used for DCEP?

Low Hydrogen Electrodes

*5, 6 & 8

5/13/2010

109

E 7018

E4918 (CSA W48-01)

Low hydrogen

Fill-freeze

All position

70,000 psi, 490 Mpa

Moderately heavy slag easy to remove

Smooth quiet arc, very low spatter, medium penetration

AC or DCEP

Iron powder addition

Electrodes

Assignment: Prepare a similar description for E7015,

E7016, E7028, E8018, E6010, E6019

Hint: Use references: Welding Technology Fundamentals,

Page 74-78, Procedure Handbook of Arc Welding

Chapter 6.2, and CSA W48-01 appendix D

5/13/2010

110

Electrode Storage

Low Alloy

Steel

Electrodes

5/13/2010

111

Electrode Designations

E 10016-D2

AWS

Electrode

Minimum tensile strength in thousand psi

Welding position

Utilization

Alloy addition

Alloy Additions

5/13/2010

112

Low Alloy Electrodes

Assignment: 1. Describe the electrodes E9018-B3L and

E6218-B3L

2. Create memory rules to help recall which

electrodes are low hydrogen, and which electrodes

cannot be used with AC

Chromium and Chromium

Nickel Electrodes

E 316L-16

Alloy designation

ElectrodePosition

Use-ability

15 all position DC only

16 all position AC/DC, (DC if available)

25 flat or horizontal position only, DC

26 flat or horizontal position AC/DC (DC if available)

Low carbon

5/13/2010

113

Chromium and Chromium

Nickel Electrodes

Team Assignment 6:

1. What electrode is used to join 304 stainless steel

to 304 stainless steel?

2. What electrode is used to join 316L stainless steel

to 316L stainless steel?

3. What electrode is used to join 304L stainless steel

to 316L stainless steel?

Hint: Procedure handbook of Arc Welding chapter 7.2

Flat Welding PositionStriking an arc

Scratch method Pecking method

5/13/2010

114

Arc Blow

Stringer Bead

Width of bead 2 to 3 times electrode diameter

Height of bead 1/8th bead width

5/13/2010

115

Weaving Bead

Width less than 6 times

Travel Angle

5/13/2010

116

Work Angle

Reading The Bead

Good bead

5/13/2010

117

Reading The Bead

Current too low

Reading The Bead

Current too high

5/13/2010

118

Reading The Bead

Arc length too short

Reading The Bead

Arc length too long

5/13/2010

119

Reading The Bead

Travel speed too slow

Reading The Bead

Travel speed too fast

5/13/2010

120

Gas Tungsten Arc Welding

Current & Heat Distribution

Constant current

5/13/2010

121

Cleaning Action

Shielding Gases

Argon

Easier to start and maintain arc

Lower flow rates

Less expensive

Helium

Hotter arc

Deeper penetration

Faster welding speeds

5/13/2010

122

Electrodes

Zirconia: AC only, Aluminum

Thoria: Steel and SS

Pure: Aluminum

Current Selection

R2 p9.4-2

5/13/2010

123

Current Selection

Current Selection

5/13/2010

124

Pulsed GTAW

Arc Starting

High frequency start

Electrode contact

5/13/2010

125

Laying A Bead

Pool formed Electrode moved to

back of puddle, filler

added to front of

puddle

Rod is withdrawn

electrode is moved

to front of puddle

Typical SS Welding Procedures

5/13/2010

126

GTAW Variations

Autogenous

Automatic

Hot Wire

Multi-Electrode

Team Assignment 7

Prepare a welding procedure including all the details your

team is capable of to perform a full penetration Butt weld

to join two 3-1/2” schedule 40, 316L pipe for use in a

pressure chemical application.

5/13/2010

127

Gas Metal Arc Welding

Metal Transfer

Short Circuit

Globular Transfer

Spray Transfer

5/13/2010

128

Short Circuit

Thin material

Out of position

Low heat transfer

Globular Transfer

Spatter, flat position

5/13/2010

129

Spray Transfer

At least 90% Argon

Pulsed Spray Transfer

Above and below transition current

Out of position

5/13/2010

130

Power Supply

Constant Potential

Inductance

Slope Adjustment

No current adjustment

Wire Feeder

5/13/2010

131

Shielding Gas

Type of transfer

Penetration and bead shape

Speed of Welding

Mechanical Properties of weld

Shielding Gas

5/13/2010

132

Shielding GasArgon: aluminum, nickel, copper magnesium

excellent arc stability

good penetration and bead profile

finger like penetration

CO2 steel

reactive gas

will not support spray transfer

greater spatter and fumes

good fusion and penetration

Helium heavy sections of Al, Cu and Mg

higher thermal conductivity

additional heat to base metal

Shielding GasArgon-Oxygen 1 to 8% Oxygen

Stainless steel

increases droplet rate

more fluid puddle

reduces undercut

Argon- CO2 Carbon and low alloy steels

Most popular 5 to 18%

More fluid puddle

Higher welding speeds

Argon- Helium Aluminum, copper, nickel alloys

Increased heat input

Deeper penetration

5/13/2010

133

Electrode Wire

ER49S-B2

Electrode

Rod

Solid

Alloy

Tensile Strength

[MPa]

Electrode Wire

5/13/2010

134

Torch Position

Torch Position

5/13/2010

135

Team Assignment 8

Flux Cored Arc Welding

5/13/2010

136

Flux Cored Arc Welding

Electrodes

1. Gas shielded

2. Self Shielded

3. Metal Cored

Gas Shielded Electrodes

Used with same equipment as GMAW

Constant voltage

Constant wire speed

Most are designed for DCEP

Gas is usually CO2 or 75% Ar / 25%CO2

Rutile wire: spray transfer only

stable arc, smooth bead

good penetration & out of position

Basic wire: short circuit and globular transfer

considerable spatter

not easy to use out of position

5/13/2010

137

Self Shielded Electrodes

Very similar to an inside out SMAW electrode

Flat and out of position wire

Immune to moisture pickup

DCEN or DECP, with long stick-out

Most fume generation

Metal Cored Electrodes

Core contains: arc stabilizers

deoxidizers

metal powders

Used with shielding gas

Short circuit/globular/spray transfer

Out of position with pulsed spray transfer

5/13/2010

138

Electrode Designations

EXXXT-1

Electrode

Tensile Strength

Tubular or C = metal cored

Grouping (27 groups /

CSA W48-01)

Welding Position

1= all, 2 = F groove and F&H fillet

Refer to CSA W48-01 figure B1

Power Supply

Constant Potential

Inductance

Slope Adjustment

No current adjustment

5/13/2010

139

Submerged Arc Welding

Three to ten times faster than SMAW

Electrodes

Typical wire size: 1/16, 5/64, 3/32”

Also cored and strip

Available for mild steel, low alloy, stainless steel and

nickel-base alloys

5/13/2010

140

Fluxes

Manufacturing: Fused (mixed, melted, fused, crushed,

screened & packaged)

Bonded (blended dry, binder added,

dried, sized & packaged)

Alloy Content

of Weld: Active (Controlled amounts of Mn & or Si

to improve resistance to porosity

and cracking)

Neutral (contains little or no deoxidizers)

Power Supplies

DCEN, DCEP, AC

DCEP recommended for deep penetration

DCEN recommended for: fillets (clean plate)

hard facing

hard to weld steels

greater build-up

AC recommended for: tandem arc

5/13/2010

141

Joint Preparation

Joint Preparation

5/13/2010

142

Joint Preparation

Backing Required

Electrode & Flux Specification

F XX X X-E L XX X

Flux

Tensile StrengthHeat Treat Condition

A = as welded, P = PWHT

Temp of impact strength

Z = impact testing not required

S = single pass only

Electrode

Mn L = low, M = medium,

H = high, C = composite electrode

If solid K = killed steel

Carbon or chemical analysis

5/13/2010

143

Team Assignment 9

Make a short presentation (7 to 10 minutes) to act as a

review for your class mates on one of the welding methods.

SMAW

GTAW

GMAW

FCAW

SAW

Heating

Preheating: Just prior to welding

Interpass heating During welding

Post weld heat treatment : After welding

5/13/2010

144

Preheating

Why?

Reduce local shrinkage stresses

Reduce cooling rate through critical temperature

(870º to 720º C) to prevent excess hardening

& lowering ductility in weld & HAZ

Reduce cooling rate around 205º C to allow more

time for hydrogen to to diffuse from weld

and adjacent plate material to avoid hydrogen

embrittlement and cracking

How Much Preheat?

Base metal chemistry

Plate thickness

Restraint

Rigidity of members

Heat input of welding process

5/13/2010

145

Guides for Preheat

Specification

Note usually given as minimum preheat and is

determined by measuring temperature for some

distance around the weld

Observe minimum ambient temperatures

Remember Q&T steels can be damaged if preheat

is to high

Guides for Preheat

5/13/2010

146

W59-03 Appendix P

W59-03 Appendix P

5/13/2010

147

W59-03 Appendix P

W59-03 Appendix P

5/13/2010

148

W59-03 Appendix P

Methods of Preheating

Production of small parts maybe best in a furnace

Natural gas premixed with air

Acetylene or propane torches

Electric strip heaters parallel to joint

5/13/2010

149

Measuring Preheat

Temperature

With the exception of Q&T steels temperatures

can be exceeded by 40º C

If temperature indicating crayons are used it is best

to have one above and one below target temperature

Pyrometers, thermocouples and infrared sensors are also

Used, calibration and proper use are important

Preheating Quench &

Tempered Steel

Q & T steel have been heat treated heating above a

certain temperature will destroy the properties of that

heat treatment

The assembly may require preheat but it must not be to high

The material must cool rapidly enough to re-establish the

original properties

Preheating and welding heat input must be closely controlled

5/13/2010

150

Interpass Temperatures

Usually steel which requires preheat is required to

remain at that temperature between passes

On massive weldments the heat input from welding

may not be sufficient to maintain the required temperature

Just as it is desirable to control the cooling rate of the weld

as a whole it is also important to control cooling between

passes

Heat from additional sources maybe required to maintain

interpass temperatures

Post Weld Heat Treatment

Annealing

Normalizing

Stress Relief

5/13/2010

151

Full Annealing

Purpose:

Make steel soft and ductile

Reduce stresses

Heat steel to 100º F above critical temperature

Hold for 1 hour per inch of thickness

Slow cool, usually in furnace

Normalizing

Purpose:

Reduce stresses, usually after welding

Greater hardness & tensile strength than

full annealing

Heat steel to 100º F above critical temperature

Hold for 1 hour per inch of thickness

Cool in still air

5/13/2010

152

Stress Relief

Purpose:

Provides dimensional stability

Softens martensitic areas

Improves fracture resistance

Heat slowly to about 625º C

Hold for a period of time

Slowly cool

Welding Procedures

CWB Pre-qualified Joints

Not pre-qualified Joints

ASME No pre-qualified joints

5/13/2010

153

CWB Pre-Qualified Joints

CSA W59-03 Section 10

SMAW, FCAW and SAW only

Weld Procedure Specification

Submit to CWB for Approval

Qualify Welders

CWB Not Pre-Qualified Joints

Welding Procedure Specification

Procedure Qualification

CWB Approval

Qualify Welders

5/13/2010

154

ASME Weld Procedures

No pre-approved joints

Each welding procedure will have a procedure

qualification record

Three types of variables: Essential

Supplementary

Non-essential

What is Included in a Welding

Procedure?

One welding procedure specification

One or more data sheets

5/13/2010

155

Welding Procedure

SpecificationScope

Welding Procedure

Base Metal

Base Metal Thickness

Preparation of Base Material

Filler Material

Shielding Gas

Position

Minimum Preheat and Interpass Temperatures

Electrical Characteristics

Welding Technique

Treatment of Underside of Groove

Weld Metal Cleaning

Quality of Welds

Storage of Electrodes

Data Sheet

5/13/2010

156

Data Sheet

CWB Welder Qualification

Classification

Process

Mode of Application

Position

5/13/2010

157

Classification

S With backing

T Without backing

FW = fillet & tack welds, ASW = arc spot weld, WT = tack welds

Process

SMAW

FCAW

GMAW

SAW

ESW

EGW

5/13/2010

158

Mode of Application

Manual

Semi-automatic

Machine Welding

Automatic

Position

Class F Flat position & horizontal fillets

Class H Flat and horizontal positions

Class V Flat, horizontal & vertical positions

Class O Flat, horizontal, vertical & overhead positions

5/13/2010

159

Electrode Designations

F4 Exx15, Exx16, Exx18

F3 Exx00, Exx10, Exx11

F2 Exx12, Exx13, Exx14

F1 Exx22, Exx24, Exx27, Exx28

Team Assignment 10

Review a weld procedure and present your teams

understanding to your class

5/13/2010

160

Verification Functions

Develop inspection plans & check lists

Ordering and delivery of material

Welding procedure specifications

Welder qualifications

Proper fit up and welding processes

Heat Treatment

Inspection

Inspection Records

Nondestructive Testing

Procurement Verification

Vendor approval

Quantity & Dimensions

Material Specification

Special Requirements

Heat treatment

Inspection

Nondestructive Testing

QA Requirements

Documentation Requirements

5/13/2010

161

Receiving Inspections

Quantity Inspections

Dimensions

Identification

Mill test reports or other required documentation

Manufacturing defects

Weather or transportation damage

Documentation Verification

Mill Test Reports

Certificates of Compliance

Partial Data Reports

5/13/2010

162

SMAW Electrode Storage

Low Hydrogen Minimum 120º C

Used within 4 hours

Alternate exposure times maybe approved

Portable storage devices maybe approved

E49 within 10 hours in portable storage

Non-Low Hydrogen Stored warm and dry

Kept free from oil and grease

Preparation for Welding

5/13/2010

163

Preparation for Welding

Assembly Fillet Welds

5/13/2010

164

Assembly Groove Welds

Workmanship

5/13/2010

165

Tack Welds

5/13/2010

166

Backing

Distortion Control

5/13/2010

167

Preheat & Interpass

Temperatures

Dimensional Tolerances

5/13/2010

168

Sweep

Camber

5/13/2010

169

Warpage and Tilt

5/13/2010

170

Misalignment

Profile of a Fillet Weld

5/13/2010

171

Fillet Weld Size

5/13/2010

172

Fillet Weld Size

Butt Weld Profile

5/13/2010

173

Groove Weld Profile

Butt Weld Profile

5/13/2010

174

Butt Weld Profile

Undercut

5/13/2010

175

Butt Weld Profile

Weld Discontinuities

5/13/2010

176

Incomplete Penetration

Lack of Fusion

5/13/2010

177

Porosity

Slag

Inclusions

5/13/2010

178

Solidification

Crack

Hydrogen Induced Cracking

5/13/2010

179

Lamellar Tearing

Arc Strikes

5/13/2010

180

Excess Convexity

Excessive Concavity

5/13/2010

181

Excessive Reinforcement

Insufficient Reinforcement

5/13/2010

182

Undercut

Discontinuities Related to

Specific Welding Methods

SMAW

SAW

GMAW & FCAW

GTAW

5/13/2010

183

SMAW

Spatter Lower current

Check polarity

Shorter arc

If molten metal running in front of arc,

change electrode angle

Watch for arc blow

Ensure electrodes are not wet

SMAW

Undercut Reduce current

Reduce travel speed

Reduce electrode size

Change electrode angle

Avoid excessive weaving

5/13/2010

184

SMAW

Rough Welding Check polarity

Check current

Ensure electrodes are not wet

SMAW

Porosity Remove scale rust and moisture

Use low hydrogen electrodes

Use shorter arc length

5/13/2010

185

SMAW

Lack of Fusion Increase current

Stringer bead technique

Ensure joint is clean

Check joint fit-up and design

Over Lap

SMAW

Incomplete Penetration Increase current

Decrease travel speed

Use smaller diameter electrode

Increase root gap

Proper electrode selection

5/13/2010

186

SMAW

Cracking Hydrogen induced cracking

Low hydrogen electrodes

Store electrodes properly

Use preheat

Smaller diameter electrodes

SMAW

Cracking Hot Cracking

Proper fit-up

Proper electrode selection

Ensure root pass is of sufficient size

Check rigidity of joint

Check Distortion control techniques

5/13/2010

187

SMAW

Cracking Solidification Cracking

If originating in crater use back

step technique

If centre bead decrease travel speed

SAW

Cracking Fillet Welds

If members 25 mm or greater ensure

gap of 1 to 1.5 mm to help with

shrinkage

Check polarity, usually DCEP but

DCEN sometimes used to

reduce penetration to help

deal with cracking

Check wire size, larger wire often used

when cracking is a problem

Check condition of root pass and fit-up

Check bead shape (1-1/4 to 1)

5/13/2010

188

SAW

Cracking Fillet Welds & T Welds

Groove angles should be at least 60º

If different materials, weld puddle

towards the most weld-able material

Increasing stick out reduces cracking

tendency

Ground at the start end of the weld

Decreasing welding speed and

current reduces cracking tendency

SAWCracking Butt Welds

If bead is hat shaped , check voltage

and travel speed, may need to be

reduced

If the first bead from the second side,

after back gouging is cracking check

to make sure the width is greater than

depth

If the steels are of poor weld-ability

often reducing current and/or travel

speed or increasing stick out reduces

dilution and reduces cracking tendency

5/13/2010

189

GMAW & FCAW

Fillet Welds Undercut & overlap are common

Check manipulation of the gun to ensure

welding of both base metals

Slag

Check for slag removal between passes

Gas Shielding is affected by ambient air movement

GTAW

Porosity Check shielding gas flow rates, leaks etc.

Check arc length (too long cannot be protected)

Tungsten Inclusions

Check for touching the electrode into the puddle

Check for current being to high

Check the size and type of electrode

5/13/2010

190

Team Assignment 11

Identify weld discontinuities in samples provided.

Record results

Mechanical Testing

5/13/2010

191

Bend Tests

Face Bend Root Bend

Bend Tests

Root Bend Face Bend

5/13/2010

192

Bend Tests

Bend Tests

5/13/2010

193

All Weld Metal Tensile Test

Reduced Section Tensile Test

5/13/2010

194

Vickers Hardness Test

Vickers Hardness Test

5/13/2010

195

Hardness Tests

Three groups:

Elastic hardness

Resistance to cutting or abrasion

Resistance to penetration

Resistance to Penetration

Brinell Hardness Test

A hard steel ball or carbide sphere is

forced into the surface under a specified

load.

Diameter is measured to determine Brinell

Hardness

BHN = Brinell Hardness Number

5/13/2010

196

Resistance to Penetration

Rockwell Hardness Method

Measures the net increase in depth of the

impression after a minor load is applied

and after the major load is applied

14 different scales

C, A & D are the most common scales

15-N, 30-N & 45-N are the most common

Superficial scales

Resistance to PenetrationVickers Hardness Test

Considered a micro hardness method

Uses a square based diamond pyramid

The surface dimensions of the indent are

measured and converted to hardness

Used for measuring case hardening and

heat affected zones of welds

VHN = Vickers Hardness Number

5/13/2010

197

Resistance to Penetration

Tukon Hardness Method

Micro hardness technique

Employs a diamond indenter

Usually combined with a Vickers unit

Resistance to Penetration

Knoop Hardness Method

Micro hardness technique

KHN = Knoop Hardness Number

5/13/2010

198

Impact Tests

Measures the decrease in

fracture resistance caused by

sudden loading in the

presence of a notch

Methods:

Charpy

Izod

Units: foot pounds of joules

Charpy Impact Tests

CVN = Charpy V-Notch

5/13/2010

199

Izod Impact Tests

Transition Temperature

Impact test results must include temperature

Most materials exhibit a change from notch tough to notch

brittle over a very narrow temperature range called the

transition temperature

Transition temperature is determined by conducting impact

tests at different temperatures until an abrupt change in

energy required to break the specimen is noted