A construction company is fabricating a large structural beam using S355JR carbon steel. The engineers specify that the weld must have good notch toughness at temperatures down to -20 °C. Which characteristic of the filler metal should the welder prioritize in order to meet this requirement?

Question: A construction company is fabricating a large structural beam using S355JR carbon steel. The engineers specify that the weld must have good notch toughness at temperatures down to -20 °C. Which characteristic of the filler metal should the welder prioritize in order to meet this requirement?

Answer options:

• High manganese and silicon content for deoxidation
• Low carbon equivalent for better weldability ✅ Good impact strength at low service temperatures
• High tensile strength to match the base metal

Correct answer: Good impact strength at low service temperatures

Explanation: For applications requiring good notch toughness at low temperatures (like -20 °C), the filler metal must inherently possess good impact strength at those temperatures. While matching tensile strength is important and deoxidizers are beneficial, they do not directly guarantee low-temperature toughness. Low carbon equivalent relates to base metal weldability more than filler metal's inherent low-temperature impact properties.