Low-alloy angle steel for corrosion resistance (e.g., weathering steel) limits sulfur (<0.035%) and phosphorus (<0.040%) to minimize embrittlement. Instead, it adds chromium (0.40-0.65%), nickel (0.25-0.50%), and copper (0.20-0.40%) to form a protective oxide layer, reducing rusting. These elements enhance atmospheric corrosion resistance without compromising mechanical properties.