Phase transformational kinetics and hardenability of alloyed medium-carbon steels

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on the kinetics of austenite t r a n s f o r m a t i o n s and h a r d e n ability of m e d i u m - c a r b o n s t e e l s : 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12) 13) 14) 15) 16)

0.39 pct 0.39 pct 0.35 pct 0.41 pct 0.37 pct 0.36 pct 0.36 pct 0.37 pct 0.36 pct 0.38 pct pet Cr, 0.37 pct 0.39 pct 0.40 pct 0.40 pct 0.40 pct 0.40 pct pct Cr.

C-0.3 C-0.3 C-0.3 C-0.3 C-0.3 C-0.3 C-0.3 C-0.3 C-0.3 C-0.3

pct pct pct pct pct pct pct pct pct pet

Si-0.8 Si-l.4 Si-0.8 Si-0.8 Si-0.8 Si-0.8 Si-0.8 Si-0.8 Si-0.8 Si-0.8

pct pct pct pct pct pct pct pct pct pct

Mn, Mn, Mn-0.3 Mn-0.3 Mn-0.7 Mn-l.5 Mn-0.7 Mn-l.4 Mn-2.6 Mn-l.4

C-0.3 C-1.5 C-1.5 C-1.5 C-1.5 C-1.5

pct pct pct pct pct pct

Si-l.4 Si-0.8 Si-l.4 Si-0.8 Si-l.4 Si-l.4

pet pct pct pct pct pct

Mn-0.7 Mn, Mn, Mn-0.7 Mn-0.7 Mn-l.4

pct pct pct pct pct pct pet pct

Cr, Cr, Cr, Cr, Ni, Ni, Ni, Ni-0.7

pet Cr,

pct Cr, pct Cr, and pct Ni-0.7

The s t e e l s of the above alloy b a s e s were p r e p a r e d at nominal molybdenum levels of 0.0, 0.25, 0.5, and 0.75 pet. The chemical compositions of the r e s u l t i n g s i x t y four s t e e l s a r e shown in Table L The base s t e e l s were induction a i r - m e l t e d as 25 kg (55 lb) heats. F o u r ingots were cast from each b a s e - s t e e l melt, each after a composition adjustment to produce the molybdenum contents noted above. Armco iron was used as the base charge m a t e r i a l . Additions were pure graphite, f e r r o silicon, f e r r o m a n g a n e s e , f e r r o c h r o m i u m , carbonyl nickel p e l l e t s , ferromolybdenum, and aluminum. The ingots were cropped, hot-forged to 30 mm (188 in.) diam b a r stock, austenitized at 870~ (1600~ for 1 h, and a i r cooled. VOLUME 4, OCTOBER 1o73-2257

Table I. Chemical Compositions of the Experimental Steels Nominal Molybdenum Steel Base

Content, pct

Element, pct C

SI

Mn

P

S

Ni

Cr

Mo

-

0.01 0.26 0.53 0.79

0.39 pct C-0.3 pct Si-0.8 pct Mn

0 0.25 0.50 0.75

0.40 0.38 0.40 0.40

0.34 0.32 0.35 0.33

0.83 0.82 0.82 0.80

0.025 0.025 0.025 0.025

0.021 0.021 0.021 0.021

0.39 pct C-0.3 pct $1-1.4 pct Mn

0 0.25 0.50 0,75

0.39 0.40 0.39 0.38

0.36 0.37 0.37 0.36

1.46 1.47 1.45 1.45

0.024 0.024 0.024 0.024

0.019 0.019 0.019 0,019

-

0.3 pct C-0.3 pct $1-0.8 pct Mn-0.3 pct Cr

0 0.25 0.50 0.75

0.36 0.35 0.35 0.34

0.38 0.39 0.38 0.38

0.83 0.83 0.80 0.80

0.025 0.025 0.025 0.025

0,020 0.020 0.020 0,020

-

0.34 0.35 0.35 0.34

0.01 0.24 0.51 0.78

0.41 pct C-0.3 pct St-0.8 pct Mn-0.3 pct Cr

0 0.25 0,50 0.75

0.41 0.40 0,41 0.41

0.36 0.36 0,35 0.34

0.86 0.87 0,84 0.84

0.023 0,023 0.023 0.023

0.018 0.018 0.018 0.018

-

0.33 0.34 0.35 0.35

0.01 0.25 0.49 0.77

0.37 pct C-0.3 pct $1-0.8 pct Mn-0.7 pct Cr

0 0.25 0.50 0.75

0.37 0.37 0.37 0.37

0.37 0.39 0.37 0.36

0.85 0.85 0.84 0.82

0,025 0.025 0.025 0.025

0.022 0.022 0.022 0.022

-

0.74 0.73 0.74 0.73

0.02 0.26 0.50 0.76

0 0.25 0.50 0.75

0.36 0.36 0.36 0.35

0.37 0.38 0.37 0.36

0.86 0.86 0.85 0.82

0,024 0.024 0,024 0,024

0.020 0,020 0.020 0.020

-

0.36 pct C-0.3 pct Si-0.8 pct Mn-l