Composition & metallurgy

Chromium improves hardenability and oxidation/wear behavior; molybdenum improves high-temperature strength and helps resist temper embrittlement. Carbon and alloy levels vary by grade.

Common grades and standards

AISI 4130, 4140, 4145, 4150; ASTM/ASME pressure grades include 1Cr-0.5Mo, 1.25Cr-0.5Mo and 2.25Cr-1Mo families such as P11/P22 and plate equivalents.

Typical applications

Boiler and refinery piping, pressure vessels, flanges, fittings, shafts, gears, wellhead components, aircraft tubing and high-strength fasteners.

Engineering characteristics

Good heat-treatment response and elevated-temperature strength. Welding commonly requires controlled preheat, consumable selection, hydrogen control and sometimes PWHT.

Known manufacturers and producer regions

Japan — Nippon Steel, JFE; India — Tata Steel, SAIL, JSW; Europe — Vallourec, voestalpine, Dillinger; China — Baowu and major seamless-tube/specialty producers; United States — specialty plate, bar and tube producers including Nucor-related operations.

Selection checklist

Confirm product form, design code, strength level, toughness/impact requirement, service temperature, corrosion exposure, weldability, forming route, heat-treatment condition, dimensional tolerance, inspection level and mill certification. Do not substitute a “similar” grade solely from a cross-reference table without checking the governing specification.

Element Folio engineering reference. Grade ranges are typical and may vary by standard. Verify the latest ASTM/ASME, EN, JIS, API or other governing specification and the mill’s current product data before procurement.