Organizations And Alloying Elements Affecting The Corrosion Resistance Of High-performance Rail Vehicle Steel

Weathering steel for tradition goods train is 09CuPTiRE or Corten-B weathering steel. Considering the requirement of raising speed, increasing loading, decreasing body weight, Ministry of Railways ordained technical conditions of weathering steel. It regulated yield strength of 400-550MPa and required the goods train will be manufactured by 450MPa high strength weathering steel, the average thickness of armor plate will be reduced about lmm. This paper will investigate the effect of alloying elements Cu, Cr, Ni and grain size on corrosion resistance of weathering steel.In this paper, three aspects were studied by metallographic analysis, cyclic immersion corrosion test, SEM, XRD, electrochemical test and so on. (1) Three kinds of Corten-B weathering steels of different grain size were prepared by different rolling and heat treat process, the effect of grain size on corrosion resistance of Corten-B weathering steel in a simulated industrial atmospheric corrosion environment was investigated. (2)The content of alloying elements Cu, Cr, Ni in weathering steel was changed, the synergism effect of alloying elements on improving the corrosion resistance of weathering steel was studied. (3) The content of Cr in weathering steel was-changed, the effect of Cr on the corrosion resistance of weathering steel was studied.The results show:(1) As the grain size of Corten-B weathering steel decreases from 30μm to 4μm, the crack and cavity in the rust after cycle immersion corrosion test decrease, the corrosion rate decreases, the atmospheric resistance is improved. (2) Incereasing the content of alloying elements Cu, Cr, Ni can improve corrosion resistance of weathering steel and enhance corrosion resistance of Corten-B weathering steel largely. SEM test shows the crack and cavity in the rust after cycle immersion corrosion test decrease, the corrosion rate decreases with the increase alloying elements content. Alloying elements Cu, Cr enrichment is clearly observed in the inner rust layer, Ni evenly distribute in the rust layer. (3) Increasing the content of alloying element Cr solely can improve the corrosion resistance of weathering steel. With the increase of Cr content, the corrosion resistance of weathering steel is improved largely. SEM test shows the crack and cavity in the rust after cycle immersion corrosion test decrease, the corrosion rate decreases with the increase alloying elements Cr content. The addition of alloying elements Cr, the rust layer of weathering steel is compact, the Cr enrichment was observed in the inner rust layer and the outer rust layer at the junction of layer.From the above, in the condition of this paper, increasing the content of alloying elements Cu, Cr, Ni simultaneously, decreasing grain size of Corten-B weathering steel, increasing Cr content solely will improve the corrosion resistance of weathering steel in atmosphere corrosion environment. In a simulated industrial atmospheric corrosion environment, the high corrosion resistance weathering steel for goods train will be obtained by increasing the content of Cu, Cr, Ni simultaneously or increasin the content of Cr solely.