Mechanical testing of weld metal

deformation and the yield strength is indicated with

the symbol Re and measured in units MPa.

Mechanical properties given in this catalogue refer

to typical values for test specimens taken from

all-weld metal material. They represent the average

obtained from a large number of tests, and for

established products they are based on the last five

years results from annual approvals check tests.

Other weld metals e.g. stainless steel, do not show

the same well marked transition boundary and in

such cases the yield strength is defined as the point

when a specified permanent deformation remains

in the test specimen after the load is removed. The

catalogue values refer to a residual deformation of

0.2% and are designated Rp 0.2%.

Test plate preparation and specimen location for

all-weld metal testing is shown in the figure below.

Two types of test specimens are prepared – cylindrical test pieces for tensile testing and square Charpy

V-Notch test pieces for impact energy testing.

Tensile Strength

The tensile test is used to determine:

•฀ Tensile Strength

•฀ Yield Strength

•฀ Elongation

Elongation

This is the maximum stress which the material under

test can be subjected to before fracture occurs and

is designated Rm.

This is a measurement of the weld metal´s ability to

deform before fracture occurs. It is designated A5

and measured as a percentage of the original test

specimen length, which is normally five times the

specimen diameter.

The impact test is used to determine:

•฀ Fracture toughness properties

Impact test

specimen

Impact energy (fracture toughness)

Impact testing is used to determine weld metal

toughness at a given temperature, under impact

loading conditions, and is a measurement of the

material´s resistance to brittle fracture. Impact

energy is determined using a V-notch test specimen according to the Charpy-V method and is

measured in the unit joule (J). Fracture toughness

values are temperature dependant and decrease

with decreasing temperature. In general a weld

metal is “safe” against brittle fracture down to the

temperature which gives a minimum impact energy

value of 47 Joule.

20mm

Tensile test

specimen

Yield Strength

The yield strength is the applied stress (load) at

which the material under test starts to yield plastically, producing a permanent deformation after the

load is removed.

Mild and carbon-manganese weld metals have a

clear transition point between elastic and plastic

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