High Temperature Oxidation Behavior Of Weathering Steel Containing Silicon

Weathering steel usually contains a variety of alloying elements,and the scale formed during hot rolling exhibits complex oxidation behavior,which causes red scale defects in hot-rolled strip products and reduces the surface quality of the product.In response to the above problems,this article mainly uses silicon-containing weathering steel Q235 NH,and Q355 NH as a supplement,conducts high-temperature oxidation behavior research,clarifies the mechanism of red scale production and proposes corresponding control measures.This article mainly draws the following conclusions:(1)The high temperature oxidation weight gain curves of Q235 NH steel with different oxygen content basically follow the parabolic law.It is concluded that the activation energies of Q235 NH steel in an oxidizing atmosphere with an oxygen content of 3%,10% and 21% are 144 k J/mol,138 k J/mol and 145 k J/mol,respectively.The activation energy of Q355 NH steel in air atmosphere is 217 k J/mol.(2)The oxide scale structure formed by Q235 NH under high temperature conditions includes the thinner Fe2O3 and Fe₃O₄ layers on the outermost layer,and the thicker FeO layer in the middle.When the heating temperature is less than 1100 ?,a silicon-rich and chromium-rich layer will be formed between the iron oxide scale and the substrate to inhibit the oxidation reaction.After the heating temperature is greater than 1100 ?,the silicon-chromium layer is destroyed,which will promote the progress of oxidation.(3)The upper and lower surface of the sample with red iron oxide scale are uneven,with obvious grid-like Fe2 Si O4,which is difficult to remove,resulting in the formation of red iron oxide scale.There is no grid-like Fe2 Si O4 found in the Q235 NH and Q355 NH iron oxide layers without red scale.Controlling the residual oxygen content in the high temperature heating zone(above 1100 ?)is an effective measure to control the production of red scale.