Weldability Study of AISI 1035 Steel Using Hydrated E6013 Electrode in Wet Tropical Climate

WELDABILITY STUDY OF AISI 1035 STEEL IN
WET TROPICAL CLIMATE USING HYDRATED
E6013-RB26 ELECTRODE
❑ Dr. Ir. Slameto Wiryolukito,
❑ Yuga Lendistanu, M.T.
Materials Science and Engineering Department, Faculty of Mechanical and Aerospace
Engineering, Institut Teknologi Bandung, Indonesia

• Water vapor absorbed into the
flux can cause hydrogen
cracking
• Higher carbon equivalent means
lower weldability
• Cheap, easy,
practical
• Commonly used
• Electrode flux
tends to absorb
water vapor
• Practical, stress
induced by self-
restraint
• Economical, samples
in small size
50
75
100
Jan Feb Mar Apr Mei Jun Jul Agt Sep Okt Nov Des
RH
(%)
Maksimum Minimum Rata-Rata
Jakarta 2015
[BMKG]
[www.twi-global.com]
[BMKG]
[AWS B4, 2016]
1st IC-DAEM & SENAMM XI 2018
Observation
Station
Yearly Average RH (%)

Source of Hydrogen in Welding Electrode
Welding
Electrode
Allowable
Moisture (%)
E6010 -
E6013 -
E70XX 0.40
E80XX 0.20
E90XX 0.15
E100XX 0.15
E110XX 0.10
Moisture in
flux
Hydrates
(·H2O)
Absorbed water
vapor
Arc Atmosphere
> 3500°C
100%
hydrogen from
hydrates exited
in weld metal
12% hydrogen
from water
vapor existed in
weld metal
Flux likely to
absorb, but easy
to release with
baking as per
manufacturer’s
recommendation
Important binder
and shield gas
former, stable up
to 1000°C
Allowable Moisture in Welding
Electrode based on AWS A5.5
[1996]
Allowable moisture for
E6013 is not specified!
[Hirai et al., 1980]

• to acquire allowable exposure duration of the E6013-RB26 electrodes
in a wet tropical atmosphere so that no crack will occur in the AISI 1035
steel weldment
• to study cracking modes in the AISI 1035 steel weldment due to
influence of level of absorbed moisture in the E6013-RB26 electrode flux
Boundary Condition
• Base Metal : AISI 1035 Steel
• Process : SMAW, WIC Test
• Electrode : Kobe Steel RB26 Φ3.2 mm (class AWS A5.1 E6013)
• Variable : Preheat/non-preheat treatment and absorbed moisture content in the
electrode flux
• Electrode hydration and welding process was implemented in room temperature environment
• Surface crack was observed 3 days after welding
Purpose

Work Flow Chart
1
st
IC-DAEM
&
SENAMM
XI
2018
Start
Preparation
As-Received
Characterization
AISI 1035 Steel
E6013-RB26
Electrode
• OpticalEmissionSpectrometry(OES)
• Hardness Test
• Tensile Test
• Metallography
• OES
• Weighing 100°C
• Weighing 91%RH
• Weighing 80%RH
• Weighing 68%RH
Electrode
Treatment
• Baking 100°C, 40’
• Hydration
• No preheat
• Preheat 150°C
Welding
(WIC Test)
Surface NDT
Metallography
Micro-Vickers
Hardness Test
Analysis
Conclusion
Finish

Steel Samples
ASTM 10 Grain-Sized Pearlitic Microstructures in AISI 1035 Steel As-Received

Weld
direction
Steel Samples

Electrode Hydration and Weighing Procedure
1] Electrode homogenization
(100°C, 40 minute) in an oven
2] Electrode
hydration using
supersaturated
salt solution agent
in air-tight
container
3] Weigh electrode in
each intended period
(0.0001 g precision),
then immediately
return the electrode to
hydration apparatus.
→ Output: absorbed
moisture mass in
electrode flux

Electrode Mass Gain Model
8
8.3
8.6
8.9
0 60 120 180
Electrode
Covering
Gross
Weight
(g)
Baking Duration (minutes); at 100°C
Function of
Absorbed Moisture
(α) Gain in E6013-
RB26 Covering over
Exposure Duration at
91%, 80%, and 68%
Relative Humidity, at
24°C
E6013-RB26 Covering Gross
Weight over Time at 100°C
Baking Temperature; Remained
Constant after 40 Minutes
1. Baking
2. Hydration
after Baking

Sample Coding and Treatment
Pre-Welding:
Variation in Preheat Treatment
and Absorbed Moisture Content
(α)
Welding:
Similar Heat Input

Surface NDT Result
• Crater (≈10 mm) at the end of weldment
is neglected in crack measurement
• Crack length is measured as straight as
relative to weld length so that crack
percentage does not beyond 100%
Dye Penetrant Result
MPI Result: NP-7 (left) vs WP-0 (right)
measure

Hardness
Hardness Test Spots [NACE MR0175]
No Preheat
634 HV =
AISI 1035
[Callister, 2014]
Preheat 150°C
• HAZ hardness was higher when
preheat was not implemented
• Even,
hardness at
some spots
were found
beyond
634 HV

martensite
phase!

Microstructures
100 μm→
Typical Hard Microstructures with Coexistence
of Martensite, Bainite, and Pearlite Formed in
HAZ of Unpreheated Samples
Ferit Widmanstätten Formed in Both
Preheated and Unpreheated Samples
Very-Fine Pearlite and Proeutectoid Ferrite
in HAZ of Samples Preheated at 150°C

Macrograph
NP-7: α = 7%, no preheat NP-0: α = 0%, no preheat WP-1.8: α = 1.83%, preheat 150°C,
section 45°
WP-1.4: α = 1.42%, preheat 150°C WP-0: α = 0%, preheat 150°C
14 mm

• Crack initiated from the weld core
which is the last place of
solidification
• Intergranular crack propagated
through ferrite widmanstätten grain
boundaries up to surface
• Based on α = 0% and the crack
morphology, it was indicated as
solidification cracking
• Conclusion: it had poor
weldability when preheat was not
implemented although dry flux was
used
Cracking Modes in Sample NP-0

Cracking Modes in Sample NP-7
• Crack initiated from HAZ, followed
by transgranular propagation
• Crack propagation turned to
intergranular in weld metal,
through the columnar structures
• Combination of hydrogen cracking
and solidification cracking

Cracking Modes in Sample WP-1.8
Chevron cracks were characterized
by cracks that appear on both sides
of the weld metal with zigzag
patterns like stairs and 45° oriented.
Low levels of hydrogen have been
believed to cause chevron cracks.
Chevron
Surface Crack
Chevron
Subsurface
Crack

Summary

Welding
Recommendation
0
2
4
6
8
10
0 4 8 12 16 20 24
α,
Absorbed
Moisture
(%)
t, Duration (hours)
91%RH
80%RH
68%RH
• Crack still appeared in
WP-1.8 case
• The WP-1.4 case was
taken as a threshold
point that not generates
any crack
• Preheat at 150°C is
mandatory
1
st
IC-DAEM
&
SENAMM
XI
2018
NP-7 NP-0 WP-1.8 WP-1.4 WP-0

Conclusion
• Without preheating, 37% solidification cracking of the weld length
occurred in a sample welded with E6013-RB26 electrodes even in
the absence of absorbed moisture content in the electrode
covering.
• The addition of the absorbed moisture up to 7% created
combination of solidification cracking and hydrogen cracking with
48% surface crack.
• On the other hand, preheating at 150°C, intergranular hydrogen
chevron crack occurred when absorbed moisture reached 1.8%
with 3% surface crack.
• Crack-free weld joint has been observed on preheat at 150°C
samples with absorbed moisture 1.4% or less.

Conclusion
• WIC test was found to be effective to study the effect of
absorbed moisture in electrode covering to the weld
soundness.
• Electrode exposure can be accurately simulated using
oversaturated salt solution as hydration agent which
gives stable relative humidity in a domestic food
container.

Bibliography
• Lampman, S. (1997): Weld Integrity and Performance, ASM International.
• Chew, B. (1976): Moisture loss and regain by some basic flux covered electrodes, Welding Journal, AWS.
• Valencia, E. and Galeano, N. (1994): Hygroscopic behavior of certain basic‐coated electrodes in a wet tropical climate, Welding
International, 8:3, 208—213.
• American Welding Society (1996): AWS B4 Standard Methods for Mechanical Testing of Welds.
• Quincot,G.,Azenha,M.,Barros,J.,andRuiFaria(2011):UseofSaltSolutionsforAssuringConstantRelativeHumidityConditionsinContainedEnvironments,
GovernodaRepúblicaPortuguesa,Guimarães.
• Jowitt, R. and Wagstaffe, P
. (1989): The Certification of the Water Content of Microcrystalline Cellulose at 10 Water Activities, Commission of the European
Communities,Luxembourg.
• Greenspan, L. (1977): Humidity fixed points of binary saturated aqueous solutions, Journal of Research of the National Bureau of
Standards, 81A:1.
• CallisterJr.,W.danRethwisch,D.(2014):MaterialsScienceandEngineering–AnIntroduction,9thEdition,Figure10.32,Wiley,USA.(AdaptedfromEdgarC.
Bain,FunctionsoftheAlloyingElementsinSteel,1939;andR.A.Grange,C.R.Hribal,andL.F.Porter,Metall.Trans.A,Vol.8A.Reproducedbypermissionof
ASMInternational,MaterialsPark,OH.)
• Tuliani, S. (1976): A metallographic study of chevron cracks in submerged arc weld metals. Welding Research International, 6:6,
19—45.
• Mota, J. dan Apps, R. (1982): Chevron cracking – a new form of hydrogen cracking in steel weld metals. Welding Research
Council.
• Lancaster, J. (1993): Metallurgy of Welding, 5th Edition, Chapman-Hall, London, UK.
• Gedeon, S. and Eagar, T. (1990): Welding Journal, 69:7, page 264—271.
• Alipooramirabad, H., Paradowska, A., Ghoamshchi, R., Hoye, N., and Reid, M. (2016): Experimental Investigation of Welding
Stresses in MWIC Weldability Test, University of Wollongong, Australia.

Weldability Study of AISI 1035 Steel Using Hydrated E6013 Electrode in Wet Tropical Climate

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