Metallographic diagram of 3Cr13 (forged into surgical billet and then air-cooled)

420J2 stainless steel or SUS 420J2 is another grade of stainless steel used in manufacturing kitchen utensils and other industrial applications like scissors and hand tools. It is a martensitic stainless steel that consists of 12-14% chromium, 0.15-0.40% carbon, 1% manganese, cater to 1% silicon, and titanium, sulfur and phosphorus. This grade of stainless steel have relatively high hardness and strength as compared to other grades.

This grade of stainless steel can be quenched to increase its hardness and strength that can be further increased in initial tempering at a very low temperature. In its annealed condition the hardness is about 264 BHS in average. This value can be increased to 452 BHS by quenching and then tempering at low temperature. The formability of SUS 420J2 is not high, but weldability is good. When it is compared with SUS 410, SUS 420J2 has lower hardening capacity and imparts fewer carbides to the weld.

Due to its properties and characteristics, SUS 420J2 is widely used in manufacturing cutting, surgical and hand tools, especially kitchen utensils, disposable knives and forks, scissors, etc. It is also used in making complex parts such as gear couplings and nuts. SUS 420J2 steel can be hardened and tempered with the help of the processes of forging and quenching. The uses of this grade of stainless steel increases its demand as they can be formed into different shapes in a very less time.

As mentioned earlier, 420J2 Stainless Steel can be processed to very high hardness, up to approximately 55 HRC. This makes it an ideal choice for making a wide range of cutting tools, such as scissors and surgical instruments. The combination of its corrosion resistance, strength, and low cost makes it very useful in these applications. In addition to cutting tools, 420J2 stainless steel can be used for other applications such as hand tools, nuts and bolts, and even food processing equipment. It is well known for its good machinability and formability, and is also very resistant to corrosion and wear.

In conclusion, SUS 420J2 is one of the most popular stainless steel grades for manufacturing kitchen utensils, scissors, and other cutting tools. Its excellent formability and good weldability, combined with its low cost make it very useful for a wide range of applications. It can be used in applications such as hand tools, fasteners, food processing equipment, and cutting tools. Its hardness can be increased through quenching and forming processes, making it a great choice in many applications.

The metallographic structure of the specimen of stainless steel 3Cr13 made of cold forging is discussed. The sample was prepared with etching and thin section method, and then observed by optical microscope. According to the metallographic analysis results, the sample is mainly composed of austenitic lath structure and ferrite grains, and there is small amount of martensite.

The austenitic lath structure distributed mainly, and the lath size was relatively large. The size of ferrite grains was even, and the shape of the grain was suitably globular. The grain boundary was clear and the morphology of grain was like hexagonal ferrite. The distributed structure was homogeneous. Martensite was found in some grain boundaries, forming small scattered particles.

The composition uniformity between various grain of 3Cr13 stainless steel was good, presumes to own much element homogenously distributed by long-time forging. Ferrite grains are uniform and feature a proper shape, demonstrating a good forging performance. The small quantity of accompanying martensite further proves its excellent mechanical property with enough hardness and strength.

Overall, the metallographic analysis results verify that the sample of 3Cr13 forged cold has excellent performance and proper metallographic structure. It is confirmed by its good mechanical property, element homogenously distribution, good-formed ferrite grains and limited martensite.