Welding AR400 Plate

What are you recommendations for welding AR400 plate?

AR400 is a quench and tempered steel and may be difficult to weld due its high strength and hardenability. The base steel around the weld rapidly heats and cools during welding, resulting in a heat affected zone (HAZ) with high hardness. Any hydrogen in the weld metal may diffuse into HAZ and may cause hydrogen embrittlement, resulting in delayed underbead or toe cracks outside of the weld. To minimize heat affected zone cracking:

  • Use a low hydrogen consumable with an -H4 or -H2 designation
  • Preheat to slow the cooling rate. Note that excessive preheat may anneal the base material
  • Slow cool. More time at elevated temperatures allows the dissolved hydrogen to escape
  • Peen the weld beads to minimize residual weld stresses
  • Use the lowest strength filler metal meeting design requirements. If making fillet welds, the weld can be oversized to give the specified strength
  • Minimize weld restraint