Abstract: An activator mixture for improving utilizable strength steels which consists essentially Ca and/or Na 16 to 30%; Si 13 to 30%; V and/or Mo 2 to 28%, Nb and/or Ta 2 to 14%, Al and/or Ba 1 to 15%; B and/or Be 0,1 to 3.0%, C1 to 5%; Fe 5 to 20% and N 1 to 10%.

Abstract: A high mechanical strength reinforcement steel able to be welded up to a determined carbon content, and stable to atmospheric corrosion, comprising, besides iron, at most 1.2% (by weight) of carbon, at most 3.5% (by weight) of manganese, at most 2.8% (by weight) of silicon, at most 1% (by weight) of molybdenum, at most 3% of copper and/or nickel, at most 0.15% (by weight) of zirconium and/or cerium and 0.04%-0.3% (by weight) of niobium and/or vanadium, 0.008 to 0.035% (by weight) of nitrogen, 0.0005 to 0.025% (by weight) of calcium, 0.02-0.15% (by weight) of aluminum and 0.001-0.05% (by weight) of boron and/or beryllium.

Abstract: A high strength steel, suitable for polishing and acid-resistant cohesion, comprising besides iron and the usual residual elements, at most 2% (by weight) of C, at most 1% (by weight) of Si, at most 5% (by weight) of Mn, at most 15% (by weight) of Cr, at most 12% (by weight) of Ni, at most 4% (by weight) of Cu, at most 3% (by weight) of Mo, at least 0.005% (by weight) of N, 0.005% to 0.25% (by weight) of Zr and/or Be, 0.001 to 0.2% (by weight) of Al, 0.04 to 1.5% (by weight) of Nb and/or V, at least 0.001% (by weight) of Ca and at least 0.001% (by weight) of B and/or Ce.

Abstract: Construction steel exhibiting a high fatigue strength.The invention relates to construction steels. These steels are essentially characterized by the fact that they comprise, besides iron, at a maximum 1.6% (by weight) of C, 0.3 to 3% (by weight) of Mn and/or Ni, at a maximum 1.8% (by weight) of Si, 0.6 to 4% (by weight) of Cu, at a maximum 3% (by weight) of Mo and/ or Co, 0.02 to 0.4% (by weight) of Nb and/or V, at a maximum 0.006% (by weight) of B, at a maximum 0.4% (by weight) of Z and/or Be, 0.2% (by weight) of Al, 0.005 to 0.2% (by weight) of N, at a minimum 0.0005% (by weight) of Ca, and at a maximum 0.25% (by weight) of Ce and/or Pb, and up to 0.1% sulfur.These steels exhibit a high fatigue strength and, up to a well defined carbon content (0.3%), a good weldability and are resistant to corrosion in the air.

Abstract: A free-cutting steel able to support dynamic stresses and exhibiting a high strength, even without hardening, and an excellent aptitude for machining by material removal, which is intended for making machine elements subjected to great stresses, which comprise, besides iron, 0.1 to 0.7% (by weight) of C, 1.2 to 3% (by weight) of Mn, at most 1% (by weight) of Si, at least 0.1% (by weight) of P, 0.05 to 0.15% (by weight) of S, at most 0.1% (by weight) of Pb, 0.001 to 0.03% (by weight) of Ca, 0.001 to 0.005% (by weight) of B, 0.007 to 0.035% (by weight) of N, 0.03 to 0.2% (by weight) of Nb and/or V, at most 0.25% (by weight of Zr and/or Ce, at most 0.2% (by weight) of Be and/or Bi, and at most 1% (by weight) of Mo and/or Ni.