420 ESR

*Always consult your Heat Treater*
      *Information Provided is General*

420 ESR is a 13% chromium tool steel which is characterized by excellent polishability, good corrosion resistance, and good wear resistance. It is a superb choice for lens quality molds where mirror finishes are desired.

420 ESR is suitable to both injection and compression molds that require high hardness and moderate corrosion resistance. It is well suited for molding poly-vinyl chlorides because of its corrosion resistance to these materials at elevated temperatures. These features also help minimize rusting during extended storage in humid environments thus decreasing die maintenance costs. The applications that 420ESR are used in are molds, cutlery, surgical and dental instruments, gauges, valves, gears, shafts, cams, and ball bearings.

420 ESR should be heated slowly to 1300 – 1400°F and gradually raise to the forging temperature of 1800 – 1900°F. The steel should be thoroughly and uniformly heated before beginning the forging operation. Do not forge when the work cools below 1650°F, but reheat as often as necessary to complete the forging.

Retard the cooling rate after forging by furnace cooling from approximately 1400°F or burying in lime, ashes, or some other insulating material in order to avoid strain cracks. This cooling method will not result in a dead soft anneal, but will leave the steel in a suitable condition for machining. Annealing of 420 ESR should be heated thoroughly at 1650°F; furnace cooled at 25° F/hr to 1100°F, and then air-cooled. A maximum hardness of 229 BHN should result. Hardening of 420ESR should be heated slowly to about 1800-1900°F. Large or complicated mold sections should be preheated between 1200 – 1400°F before raising to the higher temperature. The material should be held at the soaking temperature for about 30 minutes per inch of greatest thickness and then air or oil quenched to 120 – 150°F. Air quenching is recommended for greater assurance against quench cracking and for best size stability. However, if higher hardness is desired, oil quenching may be utilized. To obtain a hardness of 51-53, 420 ESR should be tempered in the range of 400 – 700°F for 2 hours. Tempering in the range of 800 – 1000°F should be avoided since it results in a decrease in corrosion resistance. Double tempering is suggested.

Hardening happens between 1800 – 1900°F.

420 ESR is an oversized material.


  •  Up to 1″ + .007 up to .018

  •  1″ up to 6″ + .015 up to .040

  •  6″ and up + .0625 up to .250

 Hardening Temp.: 1800 through 1900°F

 Quench Medium:    Air Oil

 Tempering Range: 800 through 1000°F

 Typical Hardness Level:    51 to 53 R/C

 Preheat Forging Temp.:    1300 through 1400°F

 Anneal Temp.:    1900 through 2000°F

 Anneal Hardness:    229 BHN

 Anneal Cooling Method:    Furnace cooled at 25°F /hr. to 1100°F,  then air cooled.

 420 ESR Material In Stock

 Color Code:   BLACK & WHITE

 Round Dimensions

  • 1″ up to 7″

  • Non-standard sizes quoted upon request.

 420 ESR Typical Analysis











 · Slight variations from typical analysis shown may occur in order to  maintain the desired graphitizing potential.