PACIFIC 4340 is available in two conditions: heat treated (quenched and tempered) to high strength or annealed for ease of machining and subsequent heat treatment. It is a nickel-chromium-molybdenum medium carbon alloy steel with deep hardenability. It can be through hardened in large sections. When properly hardened, 4340 exhibits a good combination of strength, ductility and toughness; this is the material to which other ultra-strength steels are compared. PACIFIC 4340 Heat Treated bars are hardened to 285/331 HB and meet ASTM A 434, Class BD. 4340 is weldable but only with proper precautions; because of its high hardenability, it requires both preheat and post heat in virtually all welding applications. It can be induction hardened or nitrided after quenching and tempering.
CHEMICAL COMPOSITION: Heat Analysis - ranges and limits %
| C | Mn | P | S | Ni | Cr | Mo |
|---|---|---|---|---|---|---|
.38/.43 |
.60/.80 |
.035 max |
.040 max |
1.65/2.00 |
.70/.90 |
.20/.30 |
TYPICAL PROPERTIES: ASTM A434 CLASS BD (Approximate - not for specification)
| Diameter | Tensile (psi) | Yield (psi) | Elongation |
|---|---|---|---|
over 2-1/2" thru 4" |
140,000 |
110,000 |
14% |
over 4" thru 7" |
135,000 |
105,000 |
14% |
over 7" thru 9-1/2" |
130,000 |
100,000 |
14% |
PROCESSING TEMPERATURES: Typical
| Forge | Normalize | Harden | Anneal | Temper |
|---|---|---|---|---|
2200°F max |
1550/1650°F |
1475/1550°F |
1475/1575°F |
1200°F and 400°F |
Shapes and Conditions Available:
 | Hot Rolled Annealed Rounds through 3" Diameter
| Rough Turned Oversize Annealed Rounds from 3-1/4" through 17-1/2" Diameter
| Rough Turned Oversize Heat Treated Rounds from 3-5/8" through 10" Diameter
| |
