The grooved sections of flexible structures used in mine supports have a max. localised wall thickness of over 20 mm and are constructed from heat-treatable steel contg. 0.25-0.32% C, 0.15-0.40% Si, 1.0-1.6% Mn, max. 0.035% P and max. 0.035% S, the novelty being that, in addition, the steel contains 0.015-0.07% Al, max. 0.025% N, 0.3-1.0% Cr, max. 0.05% Ti and max. 0.0035% B. Pref. max. 0.50% Mo, or alternatively max. 1.0% Ni, are added. ADVANTAGE - Distinct improvement in loading capacity in the elastic region.
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