Temper Bead Sperko Engineering 2004
Temper Bead Welding
What Is It?
Temper Bead Sperko Engineering 2014
Definition
Temper Bead Welding. A weld bead
placed at a specific location in or at the
surface of a weld for the purpose of
affecting the metallurgical properties of
the heat-affected-zone or previously
deposited weld metal. (partial)
Temper Bead
Weld Metal and HAZ
Weld Metal
HAZ HAZ
Temper Bead
Fe-C Equilibrium Phase Diagram
Alpha Iron
(BCC) Ferrite + Carbide
Austenite (FCC)
Liquid
% Carbon 0.8%
Upper Transformation (A3)
Lower Transformation (A1)
Magnetic Transformation (A2)
Temperature
1350F
1650F
2750F
Temper Bead Sperko Engineering 2004
Body-Centered Cubic
Temper Bead
Face-Centered Cubic
Temper Bead
Body-Centered Cubic
Temper Bead
Face-Centered Cubic
Temper Bead
Temper Bead
Temper Bead
Fe-C Equilibrium Phase Diagram
Alpha Iron
(BCC) Ferrite + Carbide
Austenite
(FCC)
Liquid
% Carbon 0.8
Upper Transformation (A3)
Lower Transformation (A1)
Magnetic Transformation (A2)
Tem
per
ature
1350F
1650F
2750F
0.3%
Solid
Temper Bead
Nonequilibrium Cooling
Ac3
Time
Furnace Cool
Air Cool Oil Quench
Water
Quench
Temper Bead Sperko Engineering 2004
Temper Bead
T-T-T Diagram
AR1
Pearlite
Bainite
Martensite Start
Martensite Finish
Tem
per
ature
Time (s) 10 100 1000 10000 100000
Austenite
Austenite
0
Quench and Temper
A1
A3
Rapid Cool
Time
Tem
peratu
re
Martensite
Temper Bead
Zones subject to hardening
Alpha Iron
(BCC)
Ferrite + Carbide
Austenite
(FCC)
Liquid
% C
Upper Transformation (A3)
Lower Transformation (A1)
1350F
Bead on plate
Temper Bead
Other Zones in HAZ
Alpha Iron
Ferrite + Carbide
Austenite
Liquid
% C 0.8%
Upper Transformation (A3)
Lower Transformation (A1)
1350F
1900F
Subcritical Tempering/Stress-relief
Temper Bead
Weld Zones (simple version)
Liquid (Cast)
Coarse Grain
Fine Grain
Intercritical
Subcritical
Tempered (PWHT)
Temper Bead Sperko Engineering 2004
The whole bead on plate
Temper Bead Sperko Engineering 2004
Second Pass --overlapped HAZ
Temper Bead Sperko Engineering 2004
Two layers. . . . . .
Temper Bead
The real thing. . . . .
Temper Bead
What is temper bead welding?
Temper Bead
What is temper bead welding?
Note the depth of the
HAZ of the first pass
Where is temper bead welding used?
It was first used thousands of years ago as the half-bead technique:
Deposit a layer of weld metal
Grind half of it off
Deposit a layer of weld metal
Grind half of it off
Deposit a layer of weld metal. . .
Until you are done. . . Or until you have several layers of weld metal. . . then just weld using small beads to ensure plenty of interbead tempering
Where is temper bead welding used?
Half-bead? How do you know how much of the weld was ground off???
Among other things, EPRI did some work in the 1990s and found that grinding could be eliminated by controlling heat input ratios in successive layers.
The ratio of heat input in one layer of weld to that of the previous layer is increased by about 50%, that optimizes the overlapping resulting in overlapping the
Heat Input Ratio
Where is temper bead welding used?
Very prescriptive half-bead technique was permitted in ASME Sections III and VIII for small and shallow in-process repairs of components that were already heat treated.
In 2000, ASME Section IX issued rules for qualification of temper bead WPSs based on the EPRI work to replace those rules with user-developed procedures.
QW-290 Temper Bead Welding
Used to make welds where PWHT would normally be required. Usually for repairs, but may be permitted for some new construction in the future. Fully incorporated into NBIC
Applies when permitted by construction code
Builds on existing qualifications
Requires special control of volts, amps and travel speed for each layer of weld metal
Temper Bead
Basic Qualification
All WPSs shall be qualified for groove
welding in accordance with the rules
for qualification by groove welding in
QW-202 or the rules in QW-283 for
welds with buttering and QW-214 or -
216 for overlay.
Temper Bead
Upgrading Previous Qualifications
One can upgrade an existing WPS by welding and testing a new test coupon big
enough to do the required testing
WPSs already qualified for temper bead welding can be modified for use with different temper bead variables by welding and testing a test coupon big enough to do the required
testing.
Temper Bead
Welding Process Restrictions
Temper bead welding is limited to SMAW, GTAW,
SAW, GMAW (including FCAW) and PAW.
Manual and semi-automatic GTAW and PAW are
prohibited.
Rationale: To effectively use temper bead welding,
heat input and bead size must be controlled. In
manual GTAW and PAW, the bead size is
uncontrolled.
Temper Bead
Welding Process Restrictions
TWO EXCEPTIONS:
Manual GTAW and PAW may be used for:
The root pass of groove welds made from one side
as described in paragraph QW-290.6 for making (in-process) repairs to temper bead welds.
Temper Bead
Default Qualification Basis
Unless the construction code specifies
that impact testing is the basis for
acceptance, the qualification variables
are those listed for hardness testing. In
case of conflict with QW-250 variables,
these variables apply.
Nonessential variables always apply.
Temper Bead
Impact Tests
When specified by the applicable Section or
Design Specification, the test coupon shall
be Charpy V-notch impact tested and the
supplemental variables of QW-250
applicable to the process being qualified
shall apply.
Temper Bead Sperko Engineering 2004
Hardness Variable QW-403.26
An increase in the Carbon Equivalent
IIW formula
CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15
P-number qualified still applies
Temper Bead Sperko Engineering 2004
QW-409.29
A change in the ratios of heat input
beyond the following (See Figure QW-
462.12.):
Temper Bead
Temper Bead in Groove
Temper Bead Sperko Engineering 2014
Heat Input Ratio
An increase or decrease in the ratio of heat
input between the first tempering bead layer
and the weld beads deposited against the
base metal of more than 20% for P-1 and P-3
metals and 10% for all other P-number
metals
Temper Bead Sperko Engineering 2014
Heat Input Ratio
An increase or decrease in the ratio of heat
input between the second tempering bead
layer and the first tempering bead layer of
more than 20% for P-1 and P-3 metals and
10% for all other P-number metals.
Temper Bead Sperko Engineering 2004
Heat Input Ratio
the ratio of heat input between subsequent
layers shall be maintained until a minimum
of 3/16 inches of weld metal has been
deposited over the base metal
Temper Bead
Heat Input Formula
Standard Heat input measurements:
Volts X Amps X 60 / Travel Speed or Instantaneous
Power/unit length of weld bead
Deposit Length / Unit Length of Electrode
Volume of weld metal = size (width X thickness) of
the weld bead
For machine or automatic GTAW or PAW, the power ratio
is measured as:
Power ratio = (Amperage X Voltage)
[(WFS/TS) X Af]
Temper Bead Sperko Engineering 2014
Surface Temper Beads
QW-410.58
The deletion of surface temper beads or a
change from surface temper beads that
cover the weld surface to beads that are
only deposited along the toes of the weld.
Temper Bead
Temper Bead In Butt Weld
Note 3: This is the distance from the edge of the
surface temper beads to the toe of the weld.
Surface Temper Beads
Temper Bead
Temper Bead on Plate
This layer doubles as a Surface Temper Weld Reinforcement
Sperko Engineering 2014
Temper Bead
Temper Bead applied to a
Fillet weld
Sperko Engineering 2014
Temper Bead
Surface Temper Bead Offset
Note 3: This is the distance from the edge of the
surface temper beads to the toe of the weld.
Surface Temper Weld Bead
Offset Distance S
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Temper Bead
QW-410.61
The distance S from the edge of the surface temper
weld reinforcing bead to the toe of the weld shall be
limited to the distance measured on the test coupon
1/32 +1/16 inch. Alternatively, a range for S may be
established by locating surface temper beads at
various distances from the toe of the weld followed
by hardness traverses for each distance.
Temper Bead
QW-410.63 Bead Overlap
A change in visible bead overlap
beyond +15% of that qualified. (e.g., if
the qualified overlap is 50%, the
overlap range permitted is from 35 to
65%.). Bead overlap shall measured as
shown below.
Temper Bead
Visible Bead Overlap
% Visible Overlap = (A-B)/A X 100%
A
B
Direction of bead sequence
Temper Bead
QW-410.62
Surface Grinding of Temper
Bead Layers
The addition or deletion of grinding such as flat topping or
half-bead removal of temper bead layers. Grinding
required to clean the surface or remove minor surface
flaws is permitted without specific qualification.
Half-bead just will not go away. . . .
Temper Bead Sperko Engineering 2014
Temper Bead in Groove
Note 1: Weld beads shown above may be
deposited in any sequence that will result
in placement of the beads as shown
Temper Bead
Possible Bead Sequence 1A
Temper Bead
Possible Bead Sequence 1B
Temper Bead Sperko Engineering 2014
Possible Bead Sequence 1C
Temper Bead
Possible Bead Sequence 2
Temper Bead Sperko Engineering 2014
Possible Bead Sequence 3
Temper Bead
In-process Repairs
In-process repairs are repairs in
which a flaw is mechanically
removed and a repair weld is made
before a joint is presented for final
visual inspection (i.e., the welder
blew it. . . . )
Temper Bead
In-process Repairs
For processes other than manual and
semi-automatic GTAW and PAW, repairs
shall be made using the parameters given
in the WPS for production temper bead
welding. Then guess what layer you are at
-- and use the parameters for the layer(s)
being fixed.
Temper Bead
In-Process Repairs
When it is necessary to make repairs
using manual or semi-automatic GTAW
or PAW, a WPS shall be prepared based
on PQRs developed for temper bead
welding using machine or automatic
GTAW or PAW respectively.
Bead size and heat input details must be
described in the WPS.
Temper Bead
Welder qualfication
Code has nothing special.
I recommend that each welder weld a
test coupon consisting of a mock-up
making beads of the size specified in the
WPS using the heat input specified in the
WPS. Only visual examination is
required.
What does TB welding do?
Temper Bead Sperko Engineering 2014
Modifies the microstructure of the HAZ to minimize untempered
microstructures.
1)That softens hardened structures that might be present - - like
martensite.
2)Does not soften all of the microstructure there are always local
hard spots. If hardness is an issue for service (e.g., H2S), TB
may not be a suitable option. Do testing.
3)For hardenable materials, the microstructure is predominately
tempered martensite which has excellent toughness.
4)Is of questionable value for low-hardenability metals
5)Residual stresses are still yield-point magnitude.
Temper Bead Sperko Engineering 2004
Temper Bead Welding
Grrr . . . . Arrgh!