"钢制炉体" can be translated into English as "steel furnace body" or "steel-made furnace body".
"Steel furnace body" directly describes the material (steel) and the component (furnace body) in a concise way.
"Steel-made furnace body" also conveys the same meaning, with "steel-made" emphasizing that the furnace body is made of steel.
Both expressions are acceptable, and the choice between them may depend on the specific context or personal preference.