Flexite® Chrome-Nickel- Moly Alloy Steel Bar


Flexite® is a tough, shock and fatigue resisting Chrome-Nickel- Moly alloy steel. In the delivered quenched and tempered condition, it has the highest combination of tensile strength and ductility while maintaining comparable high machinability.

Bars are delivered in the hot rolled, heat treated condition, with a hardness range of 269-341 BHN. For most applications, Flexite is both hard and tough enough to be used without additional hardening. Flexite is quenched and tempered, stress relieved and machine straightened prior to shipment. This process insures proper grain structure alignment, removal of longitudinal stress factors and confines hardness range to within 2% variance in any bar or plate section. Most air-cooled alloy products, except tool steel, cannot meet these qualifications. A slight reduction in hardness from surface to core is more desirable than “air hardened steel” since this process provides much higher ductility and resistance to shock.


  • Superior Fatigue Strength
  • Deep Hardened
  • High Tensile & Yield Strength
  • High Shear Strength
  • Uniform Fine Grain Structure
  • Easily Machinable
  • Fully Stress Relieved
  • Machine Straightened
  • Demagnetized
Flexite® Round Bar

Flexite® vs. 4140

(As Quenched Hardness (Rc))

Microsteel® vs. 4140

Available Stock Sizes

Round Bars*
3/8″ through 31/4″ in 1/8″ increments
3 1/2″ through 8 3/4″ in 1/4″ increments
9″ through 12 1/2″ in 1″ increments
13″ through 17″ in 1″ increments
Square Bars
1/2″ through 11/2″ in 1/8″ increments
1 3/4″ through 3″ in 1/4″ increments
3 1/2″ through 6″ in 1/2″ increments
Over 6" forged bars on application
1/4″ thick to 1 3/4″ thick in 1/4″ increments
2″ thick to 6″ thick in 1/2″ increments
1″ wide to 2 1/2″ wide in 1/4″ increments
3″ wide to 6″ wide in 1/2″ increments
20 - 25 Ft. (random length)

*Note: 10 ¹/₂″ diameter and over are rough turned ¹/₈″ oversized.



*max %

Physical Constants:

Density0.283 lb/in3
Melting point2600 °F
Thermal conductivity (typical steel)309 BTU in/hr.ft².°F
Coefficient thermal expansion68°F, specimen oil hardened, 1110°F temper …....…..6.83 μin/in°F
Electric resistivity(68°F )2.48x10-5Ohm*cm
Electric resistivity(212°F )2.98x10-5Ohm*cm
Elastic modulus27557-30458 ksi

Typical Properties

Tensile Strength, psi120000180000142000
Yield Strength, psi80000145000110000
Elongation, % in 2"18820
Reduction of Area, % 352238
Brinell Hardness250370260

Low Temp. Charpy Impact

Ft. Lbs. (V-Notch)

Temperature of Test
Normalized Hardened+68° F+14° F-10° F-94° F
Normalized 40Rc12.4
Hardened 35Rc81.882.387.177.3
Hardened 28Rc93.678.074.836.0


We recommend the use of St. Lawrence’s comprehensive fabrication services to eliminate processing and fabrication errors.

Cutting Keyways

Use a four or six fluted high-speed end mill; with widths up to 1/2″, use up to 60 RPM; over 1/2″ wide, reduce RPM to the 25 – 40 range. Take the full depth of keyways up to 5/8″ deep in one pass. Use two passes for depths greater than 5/8″. Use coolant to keep the cutter and steel cool. A special word about keyways – the majority of fatigue failures in shafting made from any steel can be traced back to sharp corners and notches like those found at the base of a squared corner keyway. To greatly increase your shafting life put a small radius at the corners of the key- ways and place a corresponding radius on the matching corners of the key.


Flexite has a fine grain microstructure (8-9) with closely controlled carbide particles which provide improved machinability. The oil quench and temper process of Flexite, followed by controlled stress relieving, insures against distortion and run-out commonly found in air-hardened alloys. Turning, boring and facing is more easily accomplished using mated tungsten-carbide inserts with chip-breaker. Always refer to your equipment user manual for recommended setting.


Flexite has good welding characteristics. It can be readily gas or arc welded. Welding electrodes of close to the same composition are recommended. Be sure to use a dry mated rod when arc welding. This process will retard excess grain growth. Preheating to 250° F is suggested. Since Flexite has air hardening properties, stress relieving or normalizing following the welding process is recommended. Post-heating to 300- 350° F is also acceptable.

Suggested AWS electrodes are as follows:

AWS Classifications

  • E8018-C3 7018
  • E8018-W 7018-M
  • E90180M 10018-M

Recommended Welding Currents Use AC or DC Reverse

Amps. Flat


High Speed Steel Tool
Cut DepthSpeed fpmFeed ipr


Using HSS Tool Material

Feed - Inches Per Revolution
Normal Hole Diameter - Inches
Speed fpm1/