Opportunities and dangers of using residual elements ... - Jernkontoret

Figure 11 Relationship between Cu, Ni and Sn enriched phases and surface crackingFigure 12 Influence of Cu, Ni and Sn on the surface cracking.In reference [25] it was found that in 0.1 w% C steels, boron in amounts about 7 ppmseems to reduce the susceptibility to hot-shortness by altering the ability of the Cu phase towet the surface of the austenite grain boundaries. One theory is that boron segregates to thegrain boundaries and influences the surface boundary energy in the steel. However, tocontrol the alloying to such an exact degree may be difficult.The effects of Si and P on surface hot shortness due to Cu in low carbon steels areexamined in reference [26] using a method based on tensile tests.At 1100°C, single additions of 0.4%Si and 0.02%P were effective to decreasesusceptibility to surface hot shortness, although these increased the oxidation rate. Duplexaddition of 0.4%Si and 0.02%P decreased the oxidation rate and exhibited substantialeffect on a decrease in the susceptibility. Addition of Si decreased the amount of Cu-23