This chromium-molybdenum alloy is one of the most widely used aircraft steels because of its combination of weldability, ease of fabrication, and mild hardenability. In relatively thin sections it will respond to heat treatment to high strength levels and yet in the normalized condition it has adequate strength for many applications. When resistance to wear and abrasion is required, it may be nitrided.
This grade is a quality product melted under the best steelmaking practices for aircraftmore
Unit of Measure

Specifications

Estimated Weight per Foot

2.127 lb

Estimated Weight 12-Ft. Bar

25.52 lb

Analysis

N/A Carbon .28/.33
Manganese .40/.60
Phosphorus .025 Max.
Sulphur .025 Max.
Si. .15/.35
Cr. .80/1.10
Ni. .25 Max.
Mo. .15/.25

Applications

N/A Intended for use in the manufacture of parts and components with sections 1/2" thick or less at time of heat treatment which require a through- hardening steel capable of developing hardness as high as Rockwell "C" 35, and also for parts with greater thickness requiring proportionately lower hardness. It may be used for parts requiring fusion welding. Hardenability and weldability are considered equivalent to 8630 (MIL-S-6250).

Mechanical Properties

N/A The following properties apply to material in Physical Condition F (hardened and tempered):
Tensile Strength - 125.000 psi Min.
Yield Strength - 100,000 psi Min.
Elongation in 2" - 17% Min.
Reduction of Area 55.0%

Hardening

N/A As required by MIL-S-6758, minimum end-quench hardenability values for this grade are Rockwell "C" 35 at 5/16" and Rockwell "C" 28 at 8/16"

Heat Treating

N/A Normalize—1600°/1700°F Quench—Oil
Austenitize— 1500°/1600°F Temper—700°/1250°F