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Pennsylvania Steel
flexor steel alloy alternative

Heat Treatment



Steel Tempering

The following are guidelines for the heat treatment of FLEXOR®. It is important to keep in mind that heat treatment facilities are likely to vary in their capabilities. When specifying properties it is always best to call out the Rockwell "C" hardness as the defining requirement rather than draw temperature. Many techniques are compatible with FLEXOR that will help to yield maximum properties. Please consult a Pennsylvania Steel representative to help insure you receive an optimal heat treatment process to help insure you receive the maximum properties FLEXOR has to offer.

Steel Heat Treatment Guidelines

Through Hardening

Austenitize: 1500 -1600°F (815 - 871°C), 30 minutes per inch of thickness, oil quench. (note: speed of quenchant, amount of agitation, and handling process may contribute to variance in hardening).

Temper: 350 - 1200°F (176°- 649°C) FLEXOR is primarily used with draw temperatures between 400 - 1200°F (49 - 30 HRC).

Note: It is also possible to quench in brine or water. However, this should only be done on certain applications. Quenching in water should only be done from an austenitizing temperature of 1500°F. Part geometry and section size are also key variables.


Normalizing and Stress Relieving

Normalize: 1700°F (927°C) air cool - do not slow cool. Typical normalizing will achieve a resultant hardness of 25-32 HRC.

Stress Relieve:  Post Hardened 100°F - 50°F(55-30C) below original tempering temperature. Once part is at temperature hold for 2 hours.  Air cool.


Carburize and Harden

Carburize: Gas or #1 Salts from 1650 - 1700°F (899 - 927°C) Carburizing is typically done at 1650°F with time dependent upon required case depth. FLEXOR can be carburized to a variety of case depths. Most common are .010-.015", .030", and .060". Case depths up to .120" can also be achieved. Once the desired case depth is achieved the part should be brought down to the appropriate austenitizing temperature for hardening (see Through Hardening). Do not water quench a carburized part - quench in oil or salts only.

Good Wear HRC 53-56 Case HRC 42-46 Core
Excellent Wear HRC 56-60 Case HRC 46-49 Core
Maximum Wear HRC 60-62 Case HRC 49-52 Core

Note: If excellent wear is your only objective, then the following under hardening technique is recommended. This is often used where ease in straightening and distortion is of primary concern.

Carburize (gas) all sections from 1650 - 1700°F (899 - 927°C)

Harden from 1475 - 1600°F (801 -871°C)

Oil Quench

Temper

Important! - Do not torch straighten a carburized section. Welding carburized sections should be avoided.


Nitride

FLEXOR is compatible with both gas and ion nitriding processes. Gas nitriding is typically done between 950 - 1000°F (510 - 538°C). Case depth is dependent upon furnace time. FLEXOR will typically hold a core hardness up to 41 HRC through the nitriding process. Typical distortion is less than .001".


Flame Harden

Standard flame hardening techniques should be applied. In all cases FLEXOR must be tempered after hardening. A test coupon should be used to check case depth.

Tough - Light Wear HRC 46-49 Case
High Load - Medium Wear HRC 51-54 Case
High Load – High Wear HRC 54-57 Case



Induction Harden

Standard induction hardening techniques should be applied. In all cases FLEXOR must be tempered after hardening. A test coupon should be used to check case depth.

Tough - Light Wear HRC 46-49 Case
High Load - Medium Wear HRC 51-54 Case
High Load – High Wear HRC 54-57 Case

Induction hardening usually provides more consistent case depth than flame hardening though both are compatible with FLEXOR chemistry.


Annealing

Anneal: 1450-1550°F (788- 843°C) - slow cool. Most FLEXOR is supplied in the as rolled or forged condition (normalized). Typically this will yield a hardness between 25 - 32 HRC.


Important! FLEXOR does not require annealing prior to hardening from the normalized or "as rolled" condition.

FLEXOR Colors of Hardening Heats
°F
°C
Color of Heats
752
400
Red - visible in the dark
885
474
Red - visible in the twilight
975
525
Red - visible in the daylight
1077
581
Red - visible in the sunlight
1292
700
Dull Red
1472
800
Turning to cherry
1652
900
Cherry proper
1832
1000
Bright cherry red
2012
1100
Orange red
2192
1200
Orange yellow
2372
1300
White


FLEXOR Colors of Tempering Heats
Temperature held for 1 hr
 
Temperature held for 8 min
°F
°C
Color of Oxides
°F
°C
370
188
Faint Yellow
460
238
390
199
Light Straw
510
265
410
210
Dark Straw
560
293
430
221
Brown
610
321
450
232
Purple
640
337
490
254
Dark Blue
660
349
510
265
Light Blue
710
376

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