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4142 As Rolled

4142 Normalized

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4142 Annealed

4142 Heat Treated

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PACIFIC MOLY-KROME® is available in four conditions: heat treated (quenched and tempered), annealed, normalized and as rolled. It is a widely used medium carbon alloy steel which is relatively inexpensive considering the hardenability it offers. AISI/SAE 4142 has been a standard of the industry for many moderate to severe service applications. It is readily machined, easily forged and exhibits good response to heat treating by furnace, flame and induction hardening. MOLY-KROME® can also be nitrided and is weldable using proper procedures. Both annealed and heat treated (Q & T) rounds in sizes 3-1/4" through 11" are rough turned oversize, calcium treated, vacuum degassed and ultrasonic tested.

MOLY-KROME® HEAT TREATED: This grade is quenched and tempered at the mill to a strong, tough yet machinable condition and usually requires no further heat treatment after finish machining (unless surface hardened by flame or induction). Mechanical properties are tested and certified by the supplying mill to ASTM standards A193, grade B7 and A434, class BC. (See 4340 Heat Treated for higher strength ASTM A434, Class BD.)

MOLY-KROME® ANNEALED: Pearlitic annealing produces the best machinability, the lowest hardness, the most stress free condition and the lowest strength for MOLY-KROME®. Parts made with the annealed condition generally require heat treating prior to being placed in service. Therefore, MOLY-KROME® Annealed is usually considered for parts requiring higher mechanical properties than offered by the heat treated grade; parts are machined and then heat treated.

MOLY-KROME® NORMALIZED: Heating above the critical temperature and cooling in still air produces the normalized structure. This refines the as rolled grain structure and gives mechanical properties between the quenched and tempered and the annealed conditions. This has been the traditional condition for stocking hot rolled flats and squares. Normalized MOLY-KROME® can be heat treated to higher strength/hardness levels by quenching and tempering.

MOLY-KROME® AS ROLLED (NATURAL): These bars have no controlled thermal treatment after hot rolling. Consequently machinability is inconsistent, as are mechanical properties. This condition should be considered for hot forging applications where further heat treating will be required for finished parts.

Chemical Composition

Heat Analysis - ranges and limits %

C

.40/.45

Mn

.75/1.10

P

.035 Max

S

.040 Max

Cr

.80/1.10

Mo

.15/.25

Typical Properties

Approximate - not  for specification

Annealed

.

Tensile (psi)

95,000

Yield (psi)

60,000

Hardness

197 HB

Machinability

57%

Normalized *

.

Tensile (psi)

115,000/145,000

Yield (psi)

70,000/100,000

Hardness

241/302 HB

Machinability

55%

Heat Treated (Q&T)

.

Tensile (psi)

130,000

Yield (psi)

105,000

Hardness

269 HB

Machinability

55%

*Normalized properties depend on section size. Ranges are for 1/2" through 4"

Processing Temperatures

Typical

Forge

2200°F Max

Normalize

1550/1650°F

Case Harden

1525/1575°F

Anneal 

1475/1585°F Max

Temper

750/1275°F & 350/450°F

Shapes and Conditions Available
  • As Rolled Rounds through 3" Diameter

  • Hot Rolled Annealed Rounds through 3" Diameter

  • Rough Turned Oversize Annealed Rounds from 3-1/4" through 10" Diameter

  • Press Forged Rough Turned Annealed Rounds in 12" and 14" Diameters

  • Hot Rolled Heat Treated Rounds through 3" Diameter

  • Rough Turned Oversize Heat Treated Rounds from 3-1/4" through 11" Diameter

  • Press Forged Rough Turned Heat Treated Rounds from 12" through 18" Diameter

  • Normalized Flat and Square through 4" Square

  • Annealed Hexagon through 3"