Group #4 Members: Ivan Escobar, Sam Gutierrez, Stephanie Ha,

Mohamed Salem

Information on 4340 Heat Treatment Processes Hardness Measurements Charpy Impact Tests Applications Conclusions

Investigate properties of 4340 Study failure analysis of 4340 Examine applications of 4340

Component Wt. % Compone

nt Wt. % Component Wt. %

C 0.37-0.43 Mn 0.7 P Max 0.035

Cr 0.7-0.9 Mo 0.2-0.3 S Max 0.04

Fe 96 Ni 1.83 Si 0.23

Anneal Samples placed in neutral salt bath at a

temperature of 1550˚F. Cooling rate of 100 ˚F per hour till room temperature. Had undergone recovery, recrystallization, and grain

growth. Normalize & Temper

Samples placed in a neutral salt bath at a temperature of 1650˚F.

Taken out of bath and air cooled to room temperature. Placed in air furnace at a temperature of 1250˚F to

stabilize its condition.

Hardened without Temper Placed in neutral salt bath at austenitizing

temperature of 1525˚F. Quenched in oil bath to form martensite. Washed in water bath to remove salt and oil residue.

Hardened and Temper Placed in neutral salt bath at austenitizing

temperature of 1525˚F. Quenched in oil bath to form martensite. Washed in water bath to remove salt and oil residue. Tempered in air furnace at a temperature of 850˚F.

Overheated Processed at normalize temperature for a

longer time. Then hardened and tempered to same

temperature as the hardened and tempered samples.

Was not able to reach potential hardness after heat treatment.

Rockwell Machine C Diamond Tip HRC Scale

Conditions Set 1 (Rockwell C) Set 2 (Rockwell C)

Hardened without temper 56-57 56-57

Annealed 20-25 20-25Over heated 34-35 35Hardened and tempered 40-41 41-43

Normalized 22 22

Determines the fracture properties of materials

Determine Shear and Cleavage

Conditions Set 1 (ft·Ib) Set 2 (ft·Ib)

Hardened without temper

15 16

Annealed 30 28.5

Over heated 37 38

Hardened and tempered

42.5 43

Normalized 119 117

Conditions Shear/Cleavage %

Hardened without temper 20Annealed 30Over heated 40Hardened and tempered 40Normalized 50

Hardened 20% cleavage Most ductile No shear lip

Annealed 30% cleavage Should be consistent

with Normalized Overheated

40% shear Not as brittle as

Normalized sample

Hardened w/Temper 40% Shear As brittle as

overheated sample Normalized

50% shear/cleavage Exhibit both

properties of shear/cleavage through shear lip and smooth surface

4340 Steel

Automotive Aerospace Structural Mining

Used in power train components

Bearings Crankshaft Connecting rods (H-

beams/I-beams) Input shafts

Flywheels Pinion Gears

Aircraft Landing Gear

Aircraft Frames

Used as steel rebar and steel reinforcement for structures (large buildings)

Pipe drills for mining.

4340 is best used in a hardened and tempered condition.

4340 after heat treating becomes very ductile and strong

Also has uses in different industries