Steel is the backbone of construction, manufacturing, and infrastructure—but not all steel is created equally. The open-hearth process was once the gold standard of mass steel production in the 19th and 20th centuries. This guide explores what open-hearth steel is, why it was revolutionary, and what remains of it today.

1. What Is Open-Hearth Steel?

Open-hearth steel is produced in a large shallow furnace, often gas- or oil-fired, where pig iron, scrap steel, and fluxes are melted at temperatures between 1,370–1,650 °C (2,500–3,000 °F). Impurities are burned off by flame and oxygen, and alloying elements are added before the steel is tapped and cast reddit.com+9eoxs.com+9vedantu.com+9.

2. Why It Was Historically Important

Used predominantly from the late 1800s to the mid-1900s, open-hearth furnaces enabled:

• Large batch production (up to 600 t capacity)

• High scrap usage, reducing costs

• Improved quality control compared to Bessemer steel rupertharris.com+5eoxs.com+5en.wikipedia.org+5

At its peak, this method produced a majority of global steel, essential in building railways, bridges, and skyscrapers.

3. Why It Became Obsolete

• Slow: 8–12 hours per batch vs. BOF’s 30–40 minutes en.wikipedia.org+4eoxs.com+4eoxs.com+4

• Expensive energy use: 2,500–4,000 kWh per tonne, primarily fuel metalzenith.com+1reddit.com+1

• Environmental impact: Significant CO₂, NOₓ, SO₂, and particulate emissions metalzenith.com

These inefficiencies prompted the shift to basic oxygen furnaces (BOF) and electric arc furnaces (EAF) valsider.metinvestholding.com+15thoughtco.com+15eoxs.com+15.

4. Is Open-Hearth Steel Still Used Today?

Mostly retired, but still alive in niche locations and applications:

• Widely replaced in U.S./Europe by the 1990s; China phased out by 2001; India and Ukraine held on later

• Russia retired its last OHF in March 2018 en.wikipedia.org+1eoxs.com+1

• Zaporizhstal (Ukraine) remains the largest mill still using open-hearth (7 furnaces + 1 twin-hearth) as of 2024 rupertharris.com+10en.wikipedia.org+10en.wikipedia.org+10

• Some specialty alloy steels, historical restoration projects, and military-grade steels continue to use OHF eoxs.com+1rupertharris.com+1

5. Where You’ll Still Find Open-Hearth Steel Today

• Historic structures like the Empire State Building (built in the 1930s) eoxs.com

• Old railways, bridges, WWII-era ships, and equipment—any steel made before 1980 likely used OHF eoxs.com+1eoxs.com+1

6. Modern Alternatives: BOF & EAF

• Basic Oxygen Furnace (BOF): Processes up to 400 t per charge in under 40 minutes en.wikipedia.org+15thoughtco.com+15blog.cabaro-group.com+15

• Electric Arc Furnace (EAF): Melts scrap steel via electric arcs in 30–90 minutes; flexible and eco-friendlier vedantu.com+6eoxs.com+6blog.cabaro-group.com+6

Together, these account for over 90% of global steel production en.wikipedia.org+8thoughtco.com+8reddit.com+8.

7. Why It Still Matters

• Historical integrity: Many vintage structures still rely on OHF steel

• Specialty grades: Precise temperature control can benefit certain alloys

• Educational and museum use: Several furnaces preserved for their historical value reddit.com+6britannica.com+6eoxs.com+6

✅ Key Takeaways

• The open-hearth process was groundbreaking in its time but became obsolete due to inefficiency and pollution.

• Today, only a few facilities still use OHF—most notably Zaporizhstal in Ukraine eoxs.com+9en.wikipedia.org+9britannica.com+9.

• Nearly all modern steel is produced via BOF or EAF, which offer faster, cleaner, and more economical production.

• OHF steel remains important for historical structures and specialized alloys.