In 1969 Mannesmann’s coal mining operations were folded into Ruhrkohle AG. In 1970 Mannesmann took over Thyssen’s pipe and tube manufacturing and pipelaying businesses and in return handed over its own rolled steel manufacturing and plate processing operations in Germany to Thyssen. The resulting new company Mannesmannröhren-Werke AG ranked as one of the world’s largest tubes manufacturers.
In the 1960s Mannesmann became the first of the coal and steel conglomerates to address the consistent diversification of its structure. Starting in 1968, the Group acquired G.L. Rexroth GmbH, Germany’s leading manufacturer of hydraulic components. With the acquisition of Demag AG in the years between 1972 and 1974 and Krauss-Maffei AG from 1990, Mannesmann systematically consolidated its mechanical engineering and plant construction activities. With the acquisition of Fichtel & Sachs AG in 1987 and the takeover of VDO Adolf Schindling AG and Boge GmbH in 1991 the Group also established itself in the automotive engineering market.
By 1990, a century after the company was first founded, Mannesmann was a broadly diversified technology group with a successful international presence in the fields of mechanical engineering and plant construction, drive systems and process control, electrical engineering and electronics and automotive engineering, while still continuing its original involvement in manufacturing and trading steel tube products.
The continuing process of structural change at Mannesmann was dramatically accelerated in its anniversary year 1990 with the acquisition of the license to develop Germany’s first private mobile phone network D2 and the consequent creation of the new Telecommunications Division. The company played a pioneering role in this growth sector and became the German market leader in mobile telephony within a very short period of time. In the fixed line segment a joint venture company was established in 1996 with Deutsche Bahn, which led in early 1997 to the formation of Mannesmann Arcor AG & Co. Elsewhere in Europe, joint ventures were set up with Italian and French telecommunications companies and telecoms business were wholly or partially acquired in Austria, Italy and Great Britain. Within a few years, Mannesmann consistently developed its position as the leading private telecoms provider in Europe.
While the dynamic telecommunications business steadily gained in importance within the Mannesmann Group, the other divisions were also continuously developed in the 1990s and adapted to meet changing market conditions. In the field of steel-making and tubes production, new forms of inter-company, and in some cases international, cooperation were explored. From 1990, the former Mannesmann-Hüttenwerk Huckingen in Duisburg was operated jointly by Mannesmann and Krupp as Hüttenwerke Krupp Mannesmann GmbH. In 1991 Europipe GmbH was founded in cooperation with French company Usinor Sacilor for the purpose of manufacturing large-diameter pipes, and from 1994 the stainless tube works belonging to Mannesmann, Dalmine of Italy and Vallourec of France were amalgamated under the banner of holding company DMV Stainless BV. Finally in 1997 the joint venture company V & M Tubes was established together with Vallourec to produce seamless hot-rolled steel tubes.