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AISI 420 | 1.4021 | BS 420S37 | X20Cr13 | Martensitic stainless steel

Material information according to DIN EN 10088-3

Stainless steel AISI 420 is a martensitic chromium steel that is also known under the designations 1.4021, BS 420S37, and X20Cr13. Due to its high chromium content, the material has good corrosion resistance (PREN value 12.0 - 14.0). The material can be used at temperatures up to 400°C. It has a hardness of ≤ 230 HB, a density of 7.7 kg/dm³ (at room temperature) and a tensile strength of 750 to 850 N/mm². This stainless steel grade is characterised by its good polishability, which also allows it to be polished to a high gloss. The material can be processed using all common welding methods (except arc welding) and is also well suited to forging. Other processing options include cold forming and machining. This steel is not normally used for cold heading. It is frequently used in the manufacture of cutting tools such as knives, or for decorative purposes in architecture and design.

Product range: We offer this material in our range as stainless steel wire and as rods/bars.

Specifications of the material

EN material number: 1.4021
EN short name: X20Cr13
EN standard: 10088-3
Microstructure class: martensite

Comparable standards and designations


AISI 420

B.S. 420S37

CSN 17022


PN 2H13

SS 2303
UNE F.3402

Properties and chemical composition of stainless steel AISI 420 / 1.4021

0,16 - 0,25
≤ 1,00
≤ 1,50
≤ 0,04
≤ 0,03
12,0 - 14,0

Mass fraction in % according to DIN EN 10088-3
Abbreviations: C = carbon, Cr = chromium, Cu = copper, Mn = manganese, Mo = molybdenum, N = nitrogen, Ni = nickel, P = phosphorus, S = sulphur, Si = silicon, Ti = thallium.

Physical properties

Magnetisability: present
Density (kg/dm³): 7.7
Thermal conductivity (at up to 20°C): 30
Electrical resistance at room temperature (in Ω mm²/m): 0.6
Specific heat capacity (at up to 20°C): 460

Mechanical properties

Ø in mm
Rp0,2 in MPa
Rm in MPa
A5 in %
AV in J
≤ 160
≥ 600
800 - 950
≥ 12
≥ 20
≤ 160
≥ 500
700 - 850
≥ 13
≥ 25

Abbreviations: HHB = hardness HB, WBZ = heat treatment condition

Yield strengths at elevated temperature in the solution-annealed condition

Temp in °C
100 °C
150 °C
200 °C
250 °C
300 °C
350 °C
400 °C
Rp1,0 in Mpa
≥ 515
≥ 495
≥ 475
≥ 460
≥ 440
≥ 405
≥ 355
Rp0,2 in Mpa
≥ 460
≥ 445
≥ 430
≥ 415
≥ 395
≥ 365
≥ 330

Stainless steel AISI 420 / 1.4021 is readily weldable. The material can be processed using all common welding methods such as TIG, MAG and UP welding, but is not suitable for arc welding. Care should be taken to ensure that nitrogen- or hydrogen-containing gases are not used, as these can have a negative impact on the mechanical properties of the material. Before welding, the material must be heated to between 100°C and 300°C. After welding, the material should be cooled to a temperature below 120°C before tempering at approx. 650°C as part of the heat treatment. The materials 1.4302 (X5CrNi19-9), 1.4502 (X8CrTi18) and 1.4551 (X5CrNiNb19-9) can be used as welding additives.


The material AISI 420 / BS 420S37 is readily forgeable. It should first be heated slowly to over 850°C, followed by rapid heating to 1150°C to 1180°C. Forging can then be carried out in the temperature range from 1100°C to 950°C. The material should then be cooled slowly in the furnace. If discolouration or scale forms, it must be removed, as it has a negative effect on corrosion resistance. This material can be used for freehand and joint forging.

Heat treatment and hot forming

Soft annealing (+A) (slow cooling in the furnace or in air): 745-825 °C
Hot forming (slow cooling in the furnace): 1100-800 °C
Tempering (+ QT) (cooling in air, oil or polymer): 950-1050 °C
Tempering (+ QT700) (cooling in air, oil or polymer): 650-750 °C
Tempering (+ QT800) (cooling in air, oil or polymer): 600-700 °C


The material AISI 420 has an average machinability, which depends on its hardness and strength. The machining values are comparable to those of similar steel grades.

Corrosion resistance

The martensitic stainless steel 1.4021 (AISI 420, X20Cr13) has good corrosion resistance due to its high chromium content of 12-14%. This applies in particular to non-chlorine-containing media such as organic acids, soaps or solvents. The material is resistant to scaling up to 600°C. Please note that the material is not resistant to intergranular corrosion.

Applications of stainless steel AISI 420 / 1.4021

Stainless steel AISI 420 (1.4021, X20Cr13) is widely used in various industries. In the cutlery industry, this steel is often used to make knives, scissors and other cutting tools. In the oil industry, it is often used for pump parts, valves and pipes due to its good resistance to corrosive environments. This steel is also used in mechanical engineering, for example in the manufacture of components. In the hydraulics industry, the material is used in hydraulic cylinders and components due to its strength and hardness. The automotive industry uses stainless steel AISI 420 for parts such as axles, crankshafts and gearbox components due to its wear resistance and hardness. In the chemical and petrochemical industry, the material is used in tank construction. This stainless steel is also used for decorative purposes in architecture and design, as it can be polished and refined well. It plays an important role in the food industry, especially in the production of kitchen appliances and food processing machines.

The data provided in this data sheet or material information sheet has been compiled to the best of our knowledge and is based on the current version of the relevant standard. We do not accept any liability for any errors.

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