Effects of Small Additions of Tin on High-Temperature Oxidation of Fe-Cu-Sn Alloys for Surface Hot Shortness

Abstract

Steel produced in an electric arc furnace contains a high amount of copper (Cu) that causes a surface-cracking phenomenon called surface hot shortness. It is known that tin (Sn) can exacerbate the hot shortness problem. A series of iron (Fe)-0.3 wt pct Cu-x wt pct Sn alloys with an Sn content ranging from 0.03 to 0.15 wt pct was oxidized in air at 1423 K (1150°C) for 60 seconds, 300 seconds, and 600 seconds using thermogravimetry. A numerical model developed in a previous article was applied to predict the liquid-cFe interface concentrations and interface morphology in the Fe-Cu-Sn ternary system. Scanning electron microscopy investigations show that (1) The interface between the oxide and the metal is planar as predicted by the numerical model, (2) Sn leads to severe Cu-rich liquid penetration and cracking along the grain boundaries, and (3) open cracks with Fe oxides were found beneath the oxide-metal interface. The focused ion beam serial-sectioning technique was used to reveal a three-dimensional structure of cracks in the grain boundary containing Cu-rich liquid and Fe oxides.

The Effects of Nickel/Tin Ratio on Cu Induced Surface Hot Shortness in Fe

“…The opposing effects of Ni and Sn are both related to their enrichment behavior at the oxide/metal interface, which were discussed in details in the previous papers: Ni enriches strongly in the cFe phase [11,15] whereas Sn enrich in the liquid phase [17]. The most detrimental effect of Sn results from the fact that its migration into the austenite grain boundary is aided by the liquid phase and this results in severe grain boundary decohesion [17].…”

“…On the other hand, the presence of Sn in the Cu-rich liquid was found to promote grain boundary penetration [15,16]. Sn at contents as low as 0.03 wt% causes significant grain boundary cracking [17].…”

“…The most detrimental effect of Sn results from the fact that its migration into the austenite grain boundary is aided by the liquid phase and this results in severe grain boundary decohesion [17]. As long as Sn is present in the liquid phase, it would be highly embrittling.…”

“…The numerical models coupling Comsol Multiphysics Ò [19] and Matlab Ò [20] proposed in previous papers [11,17] were applied to the current Fe-Cu-Ni-Sn system to simulate the enrichment behavior at the oxide/metal interface during the course of oxidation to quantitatively support experimental results.…”

Effect of Arsenic and Copper+Arsenic on High Temperature Oxidation and Hot Shortness Behavior of C–Mn Steel

“…Currently, a lot of research have revealed the influence of copper alone or copper + tin on the oxidation behavior and surface hot shortness of steels and involved mechanism. [3][4][5][6][7][8][9][10] However, these studies almost focused on the copper content ranging from 0.25 wt% to 1.0 wt% instead of the lower copper content more commonly produced by electric furnaces, even the oxidation behavior and surface hot shortness of steels with the lower content of coexisted copper and arsenic. So far, Yin L. et al 11) has investigated the effect of 0.06 wt%-0.1 wt%As on oxidation behavior of Fe-0.3wt%Cu alloy in the (Received on January 2, 2016; accepted on March 17, 2016) To avoid surface hot shortness of C-Mn steels containing arsenic and copper + arsenic, high temperature oxidation behavior of the steels were systematically investigated.…”