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The Mini-Mills
The steel industry disruption between 1965 and 1990 — when small, low-cost electric arc furnace producers entered at the bottom of the steel market with rebar and moved progressively upward through every product tier, displacing the integrated mills at each stage with their cost-celebration.
The mini-mill disruption of integrated steel is Christensen's canonical low-end disruption case. Beginning in the mid-1960s with rebar — the lowest-quality, lowest-margin steel product — the mini-mills used electric arc furnaces and scrap metal inputs to produce steel at approximately twenty percent lower cost than integrated mills. The integrated mills welcomed the mini-mills' entry into rebar because rebar was their least profitable product; losing it improved their margins and product mix. Over the next twenty-five years, the mini-mills progressively moved upward — into angle iron, structural components, and eventually sheet steel — and at each stage the integrated mills ceded the lower-margin segment, celebrating the improvement in their metrics. By 1990, the pattern was complete and the integrated mills' market position had collapsed.
In The You On AI Field Guide
The mini-mill case is uniquely valuable because it provides a complete cycle of low-end disruption within a single lifetime, with detailed