Grade 420 stainless steel is a high-carbon steel

Stainless steel grades that are similar to grade 420 stainless steels include martensitic steels such as the other versions of grade 420, having vanadium, sulphur and molybdenum in their composition, and the grade 440 series. Non-standard grade 420C has carbon content that is little higher than that of grade 420.

Martensitic stainless steels are ones with high hardness and high carbon content. These steels are generally fabricated using methods that require hardening and tempering treatments. The operating conditions of martensitic steels are affected by loss of material's strength at high temperatures, and decrease in ductility at negative temperatures.

Key Properties

The following properties are mentioned for bar products in ASTM A276. The specification may not necessarily be similar for other forms, such as forgings and plate.

Composition

The compositional ranges of grade 420 stainless steels are given in following table:

Table 1 - Compositional ranges of grade 420 stainless steels

Grade		C	Mn	Si	P	S	Cr
420	min. max.	0.15 -	- 1	- 1	- 0.040	- 0.03	12.0 14.0

Mechanical Properties

The key mechanical properties of grade 420 stainless steels are tabulated below:

Table 2 - Mechanical properties of grade 420 stainless steels

Tempering Temperature (°C)	Tensile Strength (MPa)	Yield Strength 0.2% Proof (MPa)	Elongation (% in 50mm)	Hardness Brinell (HB)	Impact Charpy V (J)
Annealed *	655	345	25	241 max	-
204	1600	1360	12	444	20
316	1580	1365	14	444	19
427	1620	1420	10	461	#
538	1305	1095	15	375	#
593	1035	810	18	302	22
650	895	680	20	262	42
* Annealed tensile properties are typical for Condition A of ASTM A276; annealed hardness is the specified maximum. # Tempering of this steel should be avoided in the range 425-600°C

Physical Properties

The table below provides the physical properties of grade 420 stainless steels in their annealed state:

Table 3 - Physical properties of annealed grade 420 stainless steels

Grade	Density (kg/m3)	Elastic Modulus (GPa)	Mean Coefficient of Thermal Expansion (μm/m/°C)			Thermal Conductivity (W/m.K)		Specific Heat 0-100°C (J/kg.K)	Electrical Resistivity (nΩ.m)
			0-100°C	0-315°C	0-538°C	at 100°C	at 500°C
420	7800	200	10.3	10.8	11.7	24.9	-	460	550