Heavy Hex Nuts · ASTM A194 / ASME SA-194

A194 2H Heavy Hex Nuts

The standard heavy hex nut for A193 B7 studs — quenched and tempered carbon steel, 175 ksi proof load, 24 to 35 HRC.

Robust fastener with a thicker, wider hexagonal shape for high-stress applications. Manufactured and stocked across ASTM A194 grades from 2H to 8MA, plain or coated.

ASTM A194 Grade 2H is the heavy hex nut that goes on almost every A193 B7 stud bolt. It is a medium-carbon steel with at least 0.40 percent carbon, quenched and tempered to 248 to 327 HBW in sizes up to 1½ in., and proof-load rated at 175 ksi so the nut always outlasts the stud in tension.

A194 2H Heavy Hex Nuts at a glance

Material specificationASTM A194 / ASME SA-194

UNS—

Proof load stress175 ksi heavy hex · 150 ksi hex

Hardness248–327 HBW / 24–35 HRC (≤1½ in.)

Heat treatmentQ&T, 850 °F min temper

PatternHeavy hex (ASME B18.2.2)

Typical service−20 °F to 800 °F

CertificationEN 10204 3.1 material test report with every lot, traceable to the heat

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Mechanical properties

What A194 2H must meet.

Mechanical properties — ASTM A194 Grade 2H

Nut style and size (in.)	Proof load stress (ksi)	Hardness, min	Hardness, max
Heavy hex, 1½ and under	175	248 HBW / 24 HRC	327 HBW / 35 HRC
Heavy hex, over 1½	175	212 HBW / 95 HRB	327 HBW / 35 HRC
Hex (finished pattern), 1½ and under	150	248 HBW / 24 HRC	327 HBW / 35 HRC
Hex (finished pattern), over 1½	150	212 HBW / 95 HRB	327 HBW / 35 HRC

Values per ASTM A194/A194M-24, Tables 1, 2 and 5 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.

Heat treatment

Quenched in liquid and tempered at 850 °F (455 °C) minimum.

Full A194 2H data sheet: chemistry, physical properties and standards →

Dimensions & standards