Utilize the input text as a context reference, choose the right relationship between Nucor and Steel from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Since July, U.S. steelmakers including AK Steel, U.S. Steel Corp and Nucor have filed trade petitions over imports of hot-rolled steel and cold-rolled steel.

Answer: product_or_material_produced