Hydrogen is not ideal for metal
determine the net hydrogen contents produced by the electrode's flux
Hydrogen is viewed as an eventual alternative to the raw materials of fossil-fuel power, such as coal, petroleum and natural gas. However, hydrogen is not quite ideal for metals like steel, aluminium and magnesium. Metals will become brittle and the ductility of the metal will be reduce.
Diffusible hydrogen can be introduced during manufacture from operations such as forming, coating, plating or cleaning. The most common causes of failure in practice are poorly-controlled electroplating or bad welding practice with damp welding rods. High temperature accompanying welding promotes the penetration of hydrogen into the welding pool and then into other areas of the joints.
The presence of hydrogen causes the formation of cold cracks, porosity and the embrittlement of steel. Reducing the amount of diffusible hydrogen and taking steps to reduce or eliminate residual stresses will lessen the chances of hydrogen-assisted cracking.
For hydrogen embrittlement to occur, a combination of three conditions are required:
1. the presence and diffusion of hydrogen atoms or ions
2. a susceptible material
3. stress
Application of Hydrogen Embrittlement Testing by electrode’s flux:
1) Determine the net hydrogen contents produced by
the electrode’s flux
This test first requires the electrodes to be used to produce welds of pre-determined length under laboratory controlled temperature and humidity. The welds are carefully kept at sub-zero temperatures during post-welding processing to prevent loss of hydrogen via diffusion, up until they are loaded into a gas chromatography chamber.
The coupons are heated up to a pre-determined temperature and held for a fixed duration to release the diffusible hydrogen gas within the weld. By virtue of the difference in gas molecular weight, the hydrogen gas collected can be separated from the equipment’s inert carrier gas and quantified.
2) To determine diffusible hydrogen content via Gas
Chromatography
This test primarily used as a characterization test for electrode manufacturers to certify a batch of electrodes as being low hydrogen contents according to AWS electrode specifications.
However, it can be specified as a more realistic batch verification test for end users to determine whether a stored batch of electrode is still fit for purpose as part of a quality control or troubleshooting process.
Determine Hydrogen Level
Diffusible hydrogen content in deposited metal obtained using welding process
Determine Hydrogen Level
Diffusible hydrogen content in deposited metal obtained using welding process
Common Test Method
AWS A4.3
BS EN ISO 3690
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Our state-of-the-arts hydrogen embrittlement testing lab can carry out HISC testing on nickel alloys and duplex stainless steels to investigate how hydrogen influences materials’ behaviour under mechanical stress.
For more information about how we perform Hydrogen Embrittlement (HE) Testing, call us or send us an enquiry today.
