Which welding process uses hydrogen gas as a shielding or reducing atmosphere?
A
Atomic hydrogen welding B
Submerged arc welding C
Gas tungsten arc welding D
Resistance spot welding
Analysis & Theory
Atomic hydrogen welding uses hydrogen to protect the weld and provide heat.
Hydrogen is often used in heat treatment furnaces because it acts as a:
A
Strong oxidizing agent B
Reducing agent C
Neutral gas D
Lubricant
Analysis & Theory
Hydrogen prevents oxidation by reducing metal oxides.
What is a safety concern when using hydrogen in welding and manufacturing processes?
A
It is heavier than air and accumulates on the floor B
It is non-flammable C
It forms explosive mixtures with air D
It is toxic in small concentrations
Analysis & Theory
Hydrogen is highly flammable and forms explosive mixtures with air.
In atomic hydrogen welding, the heat is generated by:
A
An electric arc between the workpiece and the electrode B
Resistance heating between the plates C
An arc struck between two tungsten electrodes in a hydrogen atmosphere D
Friction between rotating tools
Analysis & Theory
The arc between two electrodes dissociates hydrogen, releasing intense heat when recombined.
Hydrogen embrittlement is a phenomenon that affects:
A
Non-metallic materials only B
Ferrous and some non-ferrous metals C
Only plastics D
Ceramics
Analysis & Theory
Hydrogen can diffuse into metals, making them brittle and prone to cracking.
In gas welding, hydrogen can be used instead of acetylene mainly for welding:
A
Cast iron components B
High-carbon steels C
Non-ferrous metals like aluminum D
Tool steels
Analysis & Theory
Hydrogen flames are suitable for non-ferrous metals.
The flame temperature of hydrogen-oxygen flame is approximately:
A
1200 °C B
2800 °C C
3200 °C D
5000 °C
Analysis & Theory
The oxy-hydrogen flame reaches around 2800 °C.
Which property makes hydrogen suitable as a shielding gas in some specialized processes?
A
High density B
Inertness C
Reducing characteristics D
Toxicity
Analysis & Theory
Hydrogen reduces oxides and prevents contamination.
Hydrogen is produced industrially by methods such as:
A
Steam reforming of hydrocarbons B
Electrolysis of saline water C
Thermal cracking of polymers D
All of the above
Analysis & Theory
Hydrogen can be produced by all these methods.
In the context of welding, which of the following statements about hydrogen is TRUE?
A
Hydrogen flames are cooler than air-acetylene flames B
Hydrogen is never used in any welding process C
Hydrogen can be used to prevent oxidation during heating D
Hydrogen acts as an inert shielding gas
Analysis & Theory
Hydrogen is a reducing gas and prevents oxidation.