What is the maximum phosphorus content allowed in A992 angle steel?

ASTM A992/A992M-22 limits phosphorus content to 0.035% max. Phosphorus is a residual impurity that increases brittleness, especially at low temperatures, by segregating at grain boundaries. High phosphorus levels (above 0.035%) make angles prone to brittle fracture under impact or cyclic loads- a severe risk in structural applications. For example, an angle with 0.040% phosphorus might crack suddenly in cold weather, even under moderate loads. To control phosphorus, manufacturers use high-purity raw materials (iron ore, scrap) and employ ladle metallurgy to remove impurities. Post-production, each batch is tested for chemical composition, with phosphorus levels documented in the material certificate. This strict limit ensures A992 retains toughness and ductility across all service conditions.