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Phosphorus as a tramp element deteriorates the toughness and enhances the brittle fracture in high strength steels. Even very low bulk concentrations can cause severe enrichment on the prior austenite grain boundaries. This seriously restricts the applicability of highly demanded vehicle components. Three approaches were chosen to reduce the detrimental effect of phosphorus in quenched and tempered high strength CrV‐steels for high power leaf springs: Change in the chemistry (addition of boron for repelling phosphorus from the grain boundaries), application of thermomechanical treatment (TMT) instead of conventional heat treatment (CHT) (producing lattice defects as intragranular traps for phosphorus atoms) and optimizing the tempering process (balancing grain boundary segregation and lattice restoration). Whereas no effect of boron was determined, TMT reduces the sensitivity to phosphorus and leads to better ductility, especially for the highest strength Rm > 2000 MPa. The best strength ‐ ductility combination was found for the range of tempering temperatures ϑtemp between 280 and 330 °C even for phosphorus contaminated steels. Outside of this range of ϑtemp, there is a significant deterioration of ductility for P ≥ 0.02 %. Independent of P‐content, there is a dramatic decrease in 0.2 % proof strength for ϑtemp decreasing below 280 °C due to residual internal stresses.

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Ternary titanium-aluminides with compositions of Ti51Al47Fe2, Ti51A147Cr2 and Ti51Al47Mn2 were investigated with respect to the correlation of their solidification front velocity v and bulk undercooling ΔT. The observation of the solidification front during the recalescence event has been realized using a high speed video system capable of recording up to 12,000 pictures per second. The temperature measurement was carried out by pyrometry, avoiding contact with the sample. The comparison of the experimental data with the LKT-theory (Lipton, Kurz, Trivedi; [1]) refers to a primary (hcp) β-Ti solidification for undercoolings below ΔT≈ 130 K and primary (bcc) α-Ti solidification for ΔT≥ 130 K. For undercoolings ≥ 150 K the theory differs greatly from the experimental results.The maximum undercoolings achieved were 268 K (Ti51Al47Fe2), 285 K (Ti51Al47Cr2) and 280 K (Ti51Al47Mn2), corresponding to a solidification front velocity v ≈ 9-10 m/s for all alloys.

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