Hastelloy Weld Metal Grain Structure
The grain structure in Hastelloy weld metal forms during solidification through the dendritic structure. Precise control of heat input is necessary to avoid cracks.
Physical-Chemical Mechanism of Action
The grain structure in Hastelloy weld metal forms during solidification through the dendritic structure. Dendrites are crystal cells that spread in the weld pool and organize into a microscopic structural lattice.
Metallurgical Relevance & Welding Risks
An uneven grain structure can lead to crack formation. Grains that are too large or too small can impair the mechanical strength and toughness of the weld. This can cause problems especially at high temperatures and in chemically demanding environments.
Workshop Practice & Instructions
To ensure a homogeneous grain structure, it is important to control heat input precisely. This can be achieved by optimal weld speed and correct temperature regulation. A typical target grain size is about 10 to 20 µm. If needed, special shielding gases like argon can be used to stabilize the weld metal environment and avoid cracks.