Heat affected zone liquation cracking evaluation on FeMnAl alloys.

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Iron-manganese-aluminum (FeMnAl) steels offer low density and high mechanical properties, making them suitable for armored vehicle applications.
• Despite extensive research on mechanical performance and heat treatment, the weldability of FeMnAl steels requires further investigation for industrial implementation.

Purpose of the Study:

• To investigate the liquation cracking susceptibility of cast FeMnAl alloys.
• To determine the influence of key alloying elements (C, Mn, Al) on the weldability of FeMnAl steels.

Main Methods:

• Utilized the spot-Varestraint technique to assess liquation cracking.
• Employed optical and electron microscopy for microstructural analysis.
• Applied CALPHAD (Calculation of Phase Diagrams) to analyze composition-dependent cracking behavior.

Main Results:

• FeMnAl steel compositions with higher Mn and C, and lower Al content exhibited the highest susceptibility to liquation cracking.
• Conversely, compositions with lower Mn and C, and higher Al demonstrated superior resistance to cracking.
• Lower Al content promoted a fully-gamma (γ) microstructure, which is more prone to heat-affected zone (HAZ) cracking compared to ferritic (α) or duplex (α + γ) microstructures.

Conclusions:

• Alloying composition significantly impacts the liquation cracking susceptibility of FeMnAl steels.
• Optimizing Mn, C, and Al content is crucial for enhancing the weldability of these advanced steels.
• Microstructure, particularly the presence of a fully-γ matrix, plays a critical role in heat-affected zone (HAZ) cracking susceptibility.