ArcelorMittal is exploring a joint venture spinoff of its stainless steel business, worth an estimated $3bn (£1.82bn), in a sign that the biggest steelmaker is contemplating scaling back. Driven on by Lakshmi Mittal, chairman and main owner, the group has expanded on the back of acquisitions including the €26.9bn (£23.2bn) purchase of Arcelor of Luxembourg in [...]