Lab IV: Phase Transformations Sample Data

Brass 360 Aluminum 2024 Steel 4340 Steel 1018

Quench

Soft

58 HRB

Soft off-scale low HRB

no precipitates, saturated alloy solution

Hardest 43 HRCMartensite

Hardest 38 HRCmartensite or bainite

Quench + Anneal

Hardest 70 HRBOptimum large number and

small size of precipitates

Hard 40 HRCtempered martensite

Hard 32 HRCtempered martentsite or

tempered bainite

Slow CoolSoft off-scale low

HRBOveraged

Soft 94 HRBpearlite

Soft 90 HRBpearlite

Slow Cool + Anneal

Soft off-scale low HRB

Even more overaged

Soft 88 HRBtempered pearlite

Soft 74 HRB tempered pearlite

*All hardness values are from a previous quarter and should not be expected to match your data exactly, but your numbers should be in the same relative order (hardest to softest) for each material – example: for the Quenched 4340 sample, you shouldn’t expect to get exactly 43 HRC, but that sample should be the hardest of the rest of your 4340 samples

Medium Grains

Brass 360

30 % Zn

All alpha phase

550° C

Medium Grain size

70% Cu30% Zn

Quench Soft58 HRB

Quench and Anneal

Soft58 HRB

Slow Cool Soft58 HRB

Slow Cool and Anneal

Soft 58 HRB

Ha

rdn

ess m

ay slig

htin

g in

crea

se

with

lon

ge

r time

at h

igh

tem

p.

Sm

all in

crea

se in

gra

in size

Note: With no heat treatment Brass 360 is hard [74 HRB]. Heat treatment brings as received samples through recrystalization and grain growth. Must mean that samples were received cold worked

Callister sections 7.10-7.13

Callister p402

Aluminum 2024

4.4% Cu

Quench Soft off-scale lowFew, if any precipitates form. Supersaturated alloy solution

Quench and Anneal

Hardest 70 HRBOptimum large number and small size of precipitates

Slow Cool Soft off-scale lowFewer number and larger precipitates -OVERAGED

Slow Cool and Anneal

Soft off-scale low Even Fewer number and larger precipitates – even more OVERAGED

4.4% Cu1.5% Mg0.6% Mn

Age at 260*C for 20 min Precipitates and lattice strain

impedes dislocation motion

Hardness Scale ComparisonCallister p159

Steels Overview

Steel 4340 Quench Hardest 43HRC Martensite

Quench and Anneal

Hard 40 HRC Tempered Martensite

Slow Cool Soft 94 HRB pearlite and proeutectoid ferrite

Slow Cool and Anneal

Soft 88 HRB tempered pearlite and proeutectoid ferrite

0.40% Cand Cr, Mo, Mn

heat to 900*C Austentize

0.40% C

Higher Carbon content in 4340 produces more lattice distortion in martentsite phase

Quench produces martensite

Steel 1018 0.18% Cand Mn

Quench Hardest 38 HRC

Martensite

Quench and Anneal

Hard 32 HRC Tempered Martensite

Slow Cool Soft 90 HRB pearlite and proeutectoid ferrite

Slow Cool and Anneal

Soft 74 HRB tempered pearlite and proeutectoid ferrite

0.18% C

Quench produces martensite

Included in back of lab handout – use 1019 to approximate 1018 TTT behavior

Steel 4340 Isothermal transformation diagram Callister p333

Callister p343

Brass 360

Callister p341