420 1.4028 Stainless Steel is a martensitic stainless steel with 12% Chromium which is sufficient to give good corrosive resistance properties.

SUS420J1 is a kind of martensite stainless steel. It has a certain wear resistance and corrosion resistance. Its hardness is relatively high.

SUS420J2 is inexpensive and highly corrosion resistant steel. It has good corrosion resistance in mild atmosphere

Applications

Alloy 420 is used for a variety of applications where good corrosion and outstanding hardness is necessary. It is not usually used at temperatures exceeding 800oF (427oC) due to quick hardening and loss of corrosion resistance. Examples of applications that use alloy 420 include:

• Cuttery
• Knife blades
• Surgical instruments
• Needle valves
• Shear blades
• Scissors
• Hand tools

Equivalent

Chemical Composition(%)

Heat Treatment

Annealing: For maximum softness, heat uniformly to 1500 – 1650°F (816 – 899°C) and cool slowly in the furnace.

Stress Relieving: Heat at 300 – 800°F (149 – 427°C) for 1 to 3 hours, cool in air or quench in oil or water.

Hardening: Preheat, then heat to 1800 -1950°F (982 – 1066°C), soak at temperature and air cool or quench in warm oil.

Corrosion Resistance

Under hardened conditions, grade 420 steels are resistant to fresh water, alkalis, air, foods and mild acids. The steel grades with a smooth surface finish have excellent performance. The corrosion resistance properties of grade 420 will tend to fall under annealed conditions. The corrosion resistance of grade 420 is lower than that of the grade 430 Ferritic alloys with 17% chromium, grade 410 steels and other austenitic grades. This steel grade finds application in cutlery such as carving knives, table knives and so on. Grade 420 steels have good corrosion resistance against food, but continuous exposure of metals to unwashed food substances can lead to pitting corrosion.

Heat Resistance

Grade 420 stainless steels have a scaling resistance at temperatures of up to 650°C. However, temperatures above standard tempering temperature are not suitable for this grade.

Machining

Grade 420 steels can be easily machined in their annealed state, but they are difficult to machine having a hardness greater than 30HRC. One of the most readily available machined alternatives is the free-machining grade 416 steels.

Welding

The martensitic class of stainless steels has limited weldability due to its hardenability. Special consideration is required to avoid cold cracking by preheating to 550°F (260°C). Post-weld heat treatment should be considered to achieve required properties. This particular alloy is generally considered to have poorer weldability than the most common alloy of this stainless class, Type 410. A major difference is higher carbon content for this alloy which requires both preheat and post-weld heat treatment. When a weld filler is needed, AWS E/ER 420, 410 NiMo and 309L are most often specified. Type 420 is well known in reference literature and more information can be obtained in this way.