Nickel Low-Temperature Toughness Enhancement
Nickel increases the toughness of ferritic steels by increasing lattice mobility at low temperatures, making the microstructure softer and more crack-resistant.
Physical-Chemical Mechanism of Action
Nickel improves the toughness of ferritic steels by increasing lattice mobility at low temperatures. This prevents the structure from becoming too brittle and prone to cracking.
Metallurgical Relevance & Welding Risks
With too high a nickel addition, the structure can become too soft, reducing strength. This increases susceptibility to cracks and deformation. Insufficient nickel leads to a too-brittle structure with increased risk of hot cracking.
Workshop Practice & Instructions
Use nickel in the alloy to improve toughness at low temperatures. An optimal concentration of 0.5 to 1 % nickel is common. Ensure the structure does not become too soft after welding. If needed, postweld heat treatment (PWHT) can be performed to restore toughness.