4028

Alloy Steel

4028

(SAE J404). Nominal values—confirm mill certificate.

Chemical Composition (%)

C0.24
MO0.2
MN0.6
SI0.1
P0.04
S0.05

Mechanical Properties

Tensile:≥585 MPa;Yield:≥350 MPa;Elong:≥18%

Equivalent Grades

SAE J404 4028

Available Forms

Bar,Plate

Uses

Low-alloy engineering steel with enhanced hardenability and strength from alloying elements. Molybdenum (≈0.25%) raises high-temperature strength and prevents temper embrittlement. Applied to gears, shafts, bolts, connecting rods, pressure parts and heavy forgings in automotive, energy and machinery sectors.

Heat Treatment

Austenitize at 820–870 °C (oil or water quench depending on section) and temper at 400–650 °C to the required strength/toughness balance.

Precautions

Weldable with standard procedures; preheat may be needed for thick sections or higher-carbon/ alloy grades. Protect from decarburization during heating (controlled atmosphere or protective coating).

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