420J2 vs 440C Stainless Steel Bar: Heat Treatment

If you're choosing between SUS420J2 and 440C stainless steel, understanding how their differences in hardness, corrosion resistance, and edge retention impact real-world performance is essential to making the right material decision.

 

 

What is  420J2 stainless steel bar?

420J2 stainless steel bars are a martensitic high-chromium stainless steel with a chromium content of 12%-14% and a carbon content typically around 0.26%-0.40%, exhibiting good corrosion resistance. Its hardness is higher than 420J1 (reaching approximately 54-56 HRC after hardening), making it an ideal material for manufacturing durable and affordable knives, cutlery, and surgical instruments.

 

What is  440C stainless steel bar?

440C stainless steel bar is a high-carbon martensitic stainless steel, known for achieving the highest hardness (up to Rc 60), wear resistance, and strength of any stainless alloy after heat treatment. It is commonly used in, for example, high-quality knife blades, bearings, surgical instruments, and valve parts, offering good corrosion resistance. Synonyms include 1.4125, UNS S44004, and high-carbon chromium steel.

 

SUS420J2 vs. SUS440C ： Chemical Composition (wt%)

Grade	C	Cr	Si	Mn	P (max)	S (max)
SUS420J2	0.26–0.40	12.0–14.0	≤1.00	≤1.00	≤0.040	≤0.030
SUS440C	0.95–1.20	16.0–18.0	≤1.00	≤1.00	≤0.040	≤0.030

 

SUS420J2 vs. SUS440C – Mechanical Properties (After Heat Treatment)

Property	SUS420J2	SUS440C
Tensile Strength	≥700 MPa	≥760 MPa
Yield Strength (0.2%)	≥500 MPa	≥600 MPa
Elongation	≥12%	≥8%
Hardness (HRC)	50–54	58–60

 

420J2 vs 440C Stainless Steel Bar: Heat Treatment

Heat Treatment Process	AISI 420J2 (Low/Mid Carbon)	AISI 440C (High Carbon)
Annealing (Full)	840 – 900°C (Slow furnace cool)	840 – 870°C (Slow furnace cool)
Sub-critical Annealing	730 – 780°C (Air cool)	730 – 760°C (Air cool)
Preheating	Not always required; 600-700°C if complex.	Mandatory: 760 – 820°C (Equalize)
Austenitizing (Hardening)	980 – 1040°C	1010 – 1070°C
Quenching Media	Air, Oil, or Polymer	Oil (Warm) or Forced Air
Hardness after Quench	52 – 56 HRC	60 – 62 HRC
Tempering Temperature	150 – 370°C	150 – 450°C
Final Typical Hardness	50 – 54 HRC	57 – 60 HRC

 

Tempering Temperature vs. Hardness (Typical Values)

Note: Avoid tempering in the range of 400°C – 550°C for both steels, as this causes "Temper Brittleness" and a significant drop in corrosion resistance (Chromium Carbide precipitation at grain boundaries).

Tempering Temp (°C)	420J2 Hardness (HRC)	440C Hardness (HRC)	Performance Impact
150°C	53 - 55	59 - 61	Maximum hardness, lowest stress relief.
200°C	52 - 54	58 - 60	Best balance of hardness and toughness.
300°C	50 - 52	56 - 58	Improved toughness, slight loss in hardness.
400°C	48 - 50	54 - 56	Danger Zone: Reduced corrosion resistance.
600°C	25 - 30	35 - 40	Softened for high-toughness industrial parts.

 

Is 440C better than 420HC?

440C steel is generally considered superior to 420HC steel in maintaining sharpness and hardness, while 420HC steel excels in toughness and corrosion resistance. 440C steel is a high-carbon steel specifically designed for wear resistance; while 420HC steel is an affordable, corrosion-resistant, and easy-to-grind steel.

 

420J2 vs 440C Stainless Steel Bar: Applications

420J2 stainless steel bars, after heat treatment, possess good flexibility and durability (e.g., diving knives, hair clippers, surgical instruments).

440C stainless steel bars, after heat treatment, possess "sharpness retention" and wear resistance (ball bearings, high-end folding knives, valve assemblies).

 

What is the difference between 304 and 440C stainless steel?

304 stainless steel is an austenitic, non-magnetic alloy with excellent corrosion resistance and ductility, while 440C is a high-carbon martensitic steel known for superior hardness, wear resistance, and magnetism. 304 is ideal for food, chemical, and general-purpose corrosion resistance, while 440C excels in cutlery, bearings, and tools requiring high strength.

 

What is the difference between 4Cr13 and 440C steel?

440C contains significantly more carbon (1.0% vs 0.4%) and chromium (17% vs 13%) than 4Cr13, offering superior edge retention and comparable corrosion resistance. 440C can achieve much higher hardness (58-60 HRC) but typically costs 2-3 times more than 4Cr13.

 

If you have project requirements for 420J2 or 440C stainless steel bars, please feel free to place an order. GNEE has a large inventory of popular products for you to choose from. For detailed chemical composition and free samples, please contact our factory immediately. We offer competitive prices and excellent service.

420J2 or 440C stainless steel bars specifications

Size	Round	Dia 1-400mm
	Plate/Flat	Thickness 0.1mm-100mm
		Width 500mm-2000mm
Heat treatment	Normalized ; Annealed ; Quenched ; Tempered
Surface condition	Black; Peeled; Polished; Machined; Grinded; Turned; Milled
Delivery condition	Forged; Hot rolled; Cold drawn
Test	Tensile strength, Yield strength, elongation, area of reduction, impact value, hardness, grain size, ultrasonic test, US inspection, magnetic particle testing, etc.
Payment terms	T/T;L/C;/Money gram/ Paypal
Trade terms	FOB; CIF; C&F; etc..
Delivery time	7-21 days

 

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