Download - Failure analysis of 4340 steel powerpoint
Information on 4340 Heat Treatment Processes Hardness Measurements Charpy Impact Tests Applications Conclusions
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.
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
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
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