The welding tests are usually performed as butt-welding with MAG-, MMA- or laser welding. The used filler materials are normally of different types and strength levels. Different heat inputs and number of passes are sometimes used. The welding parameters are carefully registered and documented.
The welding trials are submitted to visual- and non-destructive testing. Welded joints that do not fulfil the requirements in SS-EN-ISO 15614-1:2004 are not tested.
To evaluate the weldability specimens from the welding trials are submitted to mechanical testing. The mechanical testing is to a great extent performed in accordance with SS-EN-ISO 15614-1:2004.
The tensile testing is conducted transverse to the welded joint. Testing is performed both with and without weld reinforcement. For more information about tensile testing click here.
The method used to evaluate the hardness is Vickers. Indentations are made in the weld metal, HAZ and the parent metal for measuring and recording the range of values in the welded joint. The distance between the indentations is normally in the range of 0,3 - 0,5 mm. The measured maximum value for HAZ and weld metal is documented.
A Parent Metal
B Hardness indentations
Figure 1: Typical example of hardness testing
Impact toughness testing
To evaluate the impact toughness of the welded joint the Charpy-V method is used. The specimen is machined transverse to the welded joint and the V-notch is cut perpendicular to the surface of the weld. Five different locations (A-D) in the weldment are tested, see figure 2. The different temperatures tested are in the range of 0 ºC to - 60 ºC. SSAB is normally testing impact toughness from a plate thickness of 6 mm. A reduced specimen is used for steels between 6 - 10 mm. The absorbed impact energy in the test is recalculated to J/cm2 due to the use of a specimen with reduced size, see example in figure 3.
|a - centre of weld metal
b - fusion line
c - fusion line + 1 mm
d - fusion line + 3 mm
e - fusion line + 5 mm
|1 Parent Metal|
Figure 2: Locations in the weldment where the notch is placed
A Reduced size
If the read value on the impact toughness machine is 80 J, the recalculated impact energy for the reduced size specimen to J/cm2 is:
(100/(5 x 8)) * 80 = 200
Answer: 200 J/cm2
Figure 3: Recalculation of impact energy (J) to J/cm2