PK3
  
Identification

 

Designation by Standards
Brand Name Ravne No. Mat. No. DIN EN AISI
PK3 905 1.4021 X20Cr13 X20Cr13 420

 

Chemical Composition

 

Chemical Composition in Weight %
C Si Mn Cr Mo Ni V W Others
0.20 max. 1.0 max. 1.50 13.0 - - - - -

 

General Information

Description
This alloy is a general purpose heat treatable chromium steel which is a popular cutlery grade. Martensitic stainless steel.

Applications
Dental and surgical instruments, cutlery, pump shafts, plastic molds and dies, steel balls, and various hand tools, pump components, shafts, turbine blades, pressing dies for tablets, glass and plastics processing tools.

 

Properties

Physical properties (avarage values) at ambient temperature:
Modulus of elasticity [103 x N/mm2]: 216
Density [g/cm3]: 7.73
Thermal conductivity [W/m.K]: 30.0
Electric resistivity [Ohm mm2/m]: 0.60
Specific heat capacity[J/g.K]: 0.46

Continuous Cooling Transformation (CCT) Diagram




Coefficient of Linear Thermal Expansion 10-6 oC-1
20-100 'C 20-200 'C 20-300 'C 20-400 'C 20-500 'C
10.5 11.0 11.5 12.0 12.0

Modulus of Elasticity [103 N/mm2]
20 'C 200 'C 400 'C
216 205 190

 

Heat Treatment

Soft Annealing
Heat to 730-810 'C, air cooling. Structure is ferrite with spherical carbides.

Hardening
Harden from a temperature of 950-1050 'C followed by oil, air quenching.

Tempering
Tempering temperature: 650-750 'C. Transformation structure with ferrite.

Mechanical Properties at Room Temperature
Size range mm Heat treatment condition 0.2 % proof stress (N/mm2) Tensile strength (N/mm2) Elongation (%) Notch impact energy (ISO-V) (J) Hardness HB max.
d<=160 Q+T 700 500 700-850 13 25 230
d<=160 Q+T 800 600 800-950 12 20 230

0.2 % Proof Stress (N/mm2) at Elevated Temperatures
Condition 100 'C 150 'C 200 'C 250 'C 300 'C 350 'C 400 'C
Q+T 700 460 445 430 415 395 365 330
Q+T 800 515 495 475 460 440 405 355

Diagram Hardness vs. Temperature

 

Workability

Forging
Hot forming temperature: 1100-850 'C.

Machinability
Similar to machining some of the high carbon tool steel, this alloy has tough, stringy chip build-up.
 
Other Information


Embittlemnt: It must be in mind that the temperature range between 425 and 525 'C must be avoided owing to embritllement at 475 'C.

Corrosion Resistance: 420 is resistant to the atmosphere, fresh water, dilute acids and alkalis and fruit and vegetable juices.

Welding: Not commonly welded due to its air hardening characteristics. Welding may be performed after preheating to 149-204 'C with post weld tempering at temperature for 2 hours. Filler metal should be AWS E/ER420.