Thyssen Edelstahlwerke Ag

Bernd Huchtemann

Helmut Brandis

Volker Schuler

Serosh Engineer

Peter Schuler

Dietrich Werner

Boron-containing steel products having boron contents of up to 200 ppm are obtained by an annealing process in the temperature range of between 850.degree. and 1050.degree. C. The characterizing feature of the invention is that the products are annealed in the state of equilibrium in a non-oxidizing gaseous atmosphere with a boron potential supplied by a pulverulent boron oxide source having a value such that the products retain or adsorb their boron content. The boron source is quantitatively about 100 g of B.sub.2 O.sub.3 per m.sup.3 of annealing space. In an annealing gas atmosphere mainly consisting of hydrogen, the steam partial pressure can be adjusted at atmospheric pressure in the presence of B.sub.2 O.sub.3 to the required boron activity within the range of between 10.sup.-3 to 10.sup.-5. The products can also be simultaneously case hardened during annealing. The case hardening agent can be mixed with pulverulent boron oxide as the boron source.

Process for annealing boron-containing steels and product thereof

The invention relates to a micro-alloyed pearlitic steels contain 0.20 to 0.50% C, 0.40 to 1.0% Si, 0,80 to 1,80% Mn, 0.008 to 0.2% S, 0 to 0.7% Cr, 0 to 0.1% Al, 0 to 0.04% N, 0.01 to 0.05% Ti, remainder iron and impurities resulting from the melting process, with mixed sulphides (manganese, titanium carbonitrides, and the like) precipitated on the grain boundaries. The steel may preferably contain an additional content of up to 0.20% V and/or up to 0.10% Nb.

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Krefeld, Germany

Bernd Huchtemann