How do you prevent surface hardening when gouging?

How do you prevent surface hardening when gouging?

• A. Preheat
• B. Quench
• C. Increase current
• D. Use a larger electrode

Answer: (A)

Preventing surface hardening during gouging is all about controlling how quickly the metal cools after the heat of the arc. When steel is heated and then cools rapidly, a hard, brittle surface layer can form. Preheating the workpiece raises its initial temperature, which reduces the cooling rate once the arc is removed. That slower cooling helps avoid the hard microstructure forming at the surface, making gouging easier and reducing the risk of cracking. Quenching would speed up cooling and promote hardening, which is the opposite effect. Increasing current or using a larger electrode adds heat input rather than managing the cooling rate, so they don’t specifically prevent surface hardening.

Preventing surface hardening during gouging is all about controlling how quickly the metal cools after the heat of the arc. When steel is heated and then cools rapidly, a hard, brittle surface layer can form. Preheating the workpiece raises its initial temperature, which reduces the cooling rate once the arc is removed. That slower cooling helps avoid the hard microstructure forming at the surface, making gouging easier and reducing the risk of cracking.

Quenching would speed up cooling and promote hardening, which is the opposite effect. Increasing current or using a larger electrode adds heat input rather than managing the cooling rate, so they don’t specifically prevent surface hardening.