1. No category

Experience from the workshop! Weld
recommendations for high strength steels
Mikael Reinberth, Sr Specialist, Joining and Thermal Cutting Technology
General aspects
 All conventional welding methods can
be used
 Can be welded to all weldable steels
 Heat input/t8/5 should be controlled
 Max. heating temperature:
►
►
►
►
►
►
►
Dx 355 - 700
Dx 900 - 960
Dx 1100
Wx 460 - 700
Wx 960
Wx 1100
Wx 1300
650ºC
400ºC
200ºC
580ºC
550ºC
200ºC
200ºC
Filler material
Rm (MPa)
Recommended
strength of
welds
subjected to
high stresses
1100
1000
MAG
MAG
(Solid wire)
(FCAW)
(MCAW)
A5.5 E 120X
A5.28 ER120S-X
A5.29 E12XT-X
A5.28 E120C-X
A5.23
F12X
A5.5 E 110X
A5.28 ER110S-X
A5.29 E11XT-X
A5.28 E110C-X
A5.23
F11X
A5.5 E 100X
A5.28 ER100S-X
A5.29 E10XT-X
A5.28 E100C-X
A5.23
F10X
A5.5 E 90X
A5.28 ER90S-X
A5.29 E9XT-X
A5.28 E90C-X
A5.23
F9X
A5.5 E 80X
A5.18 ER80S-X
A5.29 E8XT-X
A5.28 E80C-X
A5.23
F8X
A5.5 E 70X
A5.18 ER70S-X
A5.29 E7XT-X
A5.28 E70C-X
A5.23
F7X
(solid wire/flux
combinations)
Domex 960-1100, Weldox 960 - 1300
Domex 650 – 700 MC, Weldox 700
Domex 550 – 600 MC
900
Domex 500 MC
HARDOX
Domex
Domex 220 - 460 MC
Recommended
strength of all
other welds
SAW
MAG
MMA
800
700
600
500
8
Recommended t8/5-intervals
Requirement: min. 27 J at -40ºC
Steel grade
Recommended t8/5 intervals
Weldox 700
5 – 25 s
Weldox 900
5 – 20 s
Weldox 960 - 1300
5 – 15 s
Domex 355 – 500 MC 2 – 25 s
Domex 550 – 700 MC 2 – 10 s
Domex 900 - 1100
t8 / 5
5 – 15 s
Q 2 
1
 4300  4 ,3  T0   10  2  
d  500  T0

5

1
1
t 8 / 5  6700  5  T0   Q  

 500  T0 800  T0
Q = Heat input (kJ/mm)
d = Single plate thickness (mm)
T0 = Working temperature (ºC)
F2 = Shape factor
F3 = Shape factor
2
 
1
  
  800  T0



2

  F2


  F3

Use WeldCalc to calculate and optimize the weld procedure
Max interpass temperature
Steel Grade
Temperature (ºC)
Weldox 700 - 960
300
Weldox 1100 - 1300 200
Domex 700 MCE
100
Domex 900 - 1100
200
Static strength of high strength joints
Weldox 700
Rp0,2
[Mpa]
700-780
Rm
[Mpa]
780-830
Base material / HAZ
Weldox 900
780-850
940-1000
HAZ / Weld metal
Weldox 960
900-980
1000-1050
HAZ / Weld metal
Weldox 1100
950-1030
1010-1090
HAZ / Weld metal
Weldox 1300
1000-1100
1100-1200
HAZ / Weld metal
Domex 700
700 - 780
760 - 850
Base material / HAZ
Domex 960
960 - 1070
1020 - 1140
HAZ / Weld metal
Domex 1100
950 – 1070
1010 - 1180
HAZ
Steel grade*
Typical location of fracture
Weldox – hardness profile
Weldox 700, 900, 960
Weldox – hardness profile
Weldox 1030, 1100, 1300
Hydrogen crack
 Formed at low temperatures
(< 200 °C)
 Located in the HAZ or in the
weld metal
 Three different parameters
has to coincide in order to
obtain hydrogen cracks:
 Brittle microstructure
 Hydrogen

Filler metal

Plate surface

Atmosphere (1 – 2ml/100g)
 Tensile stresses
Hydrogen crack in HAZ
Min. preheat temp. for Weldox
The table below is valid for heatinputs of 1.7kJ/mm or higher
For heat inputs between 1.0-1.6 kJ/mm. Increase the the preheat temperature with 25°C
for cases where elevated preheat temperatures are required. For heatinputs lower than
1.0 kJ/mm use WeldCalc or EN 1011-2
*Consumable determine the preheating temperature if its carbon equivalent + 0.03 is higher
than that of the plate
Joint preparation
► Machining
► Milling
► Thermal cutting
► Flame cutting
► Laser cutting
► Plasma cutting
Type of joints
28
Joint configurations
 For thicker plates changes in the mechanical properties
in the center line is more pronounced. As a
consequence, unsymmetrical joints are beneficial for
enhanced resistance to hydrogen cracks
Factors Affecting the Fatigue Strength in
Welded Joints
Load


Due to residuals stresses
t
Load
Stress
peaks

Butt weld
Slaggs, inclusions,
Cold laps, undercut, etc
How to Improve Fatigue Strength in Welds
 Create compressive residual stress
 Improve to geometry of the weld toe

Lower
Peaks
HFMI in General
 Cylindrical indenters accelerated against the object
 Frequency above 90 Hz
 Material highly plastically deformed
HFMI, Tools
Example of Welded Joints to Consider
Examples of Welded Joints Not Suitable
maximum possible improvement, # of FAT classes
Proposed Fatigue Strength Improvement
Proposal for HFMI treated welds, m=5
8
7
6
5
4
IIW guideline for needle or hammer peening, m=3
3
2
1
0
0
1
2
3
4
235‐355 355‐550 550‐750 750‐950 over 950
fy (MPa)
[3] Yildirim, H. C. and Marquis, G. B., Fatigue strength improvement factors for high
strength steel welded joints treated by high frequency mechanical impact, , Int J Fatigue,
44, 2012, pp. 168-176.
5
Summary of the Effect of HFMI
 As welded: 71 MPa at 2 million cycles (independent of steel
grade)
 HFMI Treated: 180 MPa at 2 million cycles, using 960 material
 Improvement in stress by more than the double – or 105
times longer fatigue life!
Limitations
 Improvement is dependent on the stress ratio (R-value)
 Thickness between 5 and 50 mm
 For original FAT-classes 50-90
 Maximum stress 0.8 of yield stress
Thank You!
Thank You!