Peritectic phase is used to explain which welding phenomenon?

Peritectic phase is used to explain which welding phenomenon?

• A. Hydrogen-induced cracking
• B. Porosity in welds
• C. Hot cracking
• D. Undercut

Answer: (C)

Hot cracking is explained by the peritectic phase during solidification. In some weld metals, as the melt cools, a peritectic reaction occurs where a liquid phase reacts with a solid phase to form a different solid phase (for example, liquid plus one solid transforming to another solid). This creates a narrow, often low-melting liquid film at grain boundaries that can be trapped as the material solidifies. Under the tensile stresses and slow diffusion conditions present during cooling, this liquid film is prone to cracking, producing hot (solidification) cracks in the weld or heat-affected zone. Other defects have different causes: porosity comes from gas entrapment, hydrogen-induced cracking from hydrogen embrittlement, and undercut from welding parameters and filler-metal/metallurgy interactions at the surface. The peritectic transformation specifically describes a phase change pathway that leads to cracking in the hot state, hence it best explains hot cracking.

Hot cracking is explained by the peritectic phase during solidification. In some weld metals, as the melt cools, a peritectic reaction occurs where a liquid phase reacts with a solid phase to form a different solid phase (for example, liquid plus one solid transforming to another solid). This creates a narrow, often low-melting liquid film at grain boundaries that can be trapped as the material solidifies. Under the tensile stresses and slow diffusion conditions present during cooling, this liquid film is prone to cracking, producing hot (solidification) cracks in the weld or heat-affected zone.

Other defects have different causes: porosity comes from gas entrapment, hydrogen-induced cracking from hydrogen embrittlement, and undercut from welding parameters and filler-metal/metallurgy interactions at the surface. The peritectic transformation specifically describes a phase change pathway that leads to cracking in the hot state, hence it best explains hot cracking.