2Cr13 (tempering treatment) metallographic diagram

AISI 420 (2Cr13) (Annealed) Microstructure

AISI 420 (2Cr13) is a martensitic stainless steel of the chromium-steel family and is annealed for improved ductility. This alloy has a higher carbon content than 410, which provides superior hardness and strength when tempered. Furthermore, this grade is non-magnetic, which allows it to be machined and processed easier than other steels. AISI 420 is recommended for use in applications where good corrosion resistance and higher hardness are required. The alloy is also used in components of heavy machinery, medical instruments and tools, and in the automotive and aerospace industries.

The microstructure of AISI 420 (2Cr13) after annealing are shown in Figure 1. The ferrite consists of a two-phase microstructure with a very fine network of needle-like austenite grains which appear uniformly distributed within a network of ferrite grains. The bainite is also a two-phase microstructure consisting of martensite that has recrystallized to form needle-like martensite grains embedded in a ferrite matrix. The martensite is relatively uniform in size and shape.

The second phase of the microstructure is the carbide of chromium. Chromium carbides appear as very small, needle-like particles that appear homogeneously scattered throughout the microstructure. Chromium carbides are known contributing factors to the alloy’s strength, hardness and wear resistance. The carbides are very small and dispersed, which is why they are not visible in the micrographs.

The microstructure of AISI 420 (2Cr13) is dominated by two main phases, The ferrite and bainite are the main strengthening phase and the chromium carbides are the secondary strengthening phase. The annealed microstructure consists of a combination of advanced ferrite, bainite and chromium carbides which presents an ideal balance of strength and ductility. The annealing process optimizes the microstructure and improves the materials’ mechanical properties by relieving internal stresses and refining the crystalline grain size.

Overall, the microstructure of AISI 420 (2Cr13) after annealing presents a balanced structure which provides great strength, wear resistance and good ductility. Moreover, the alloy’s ability to be machined is greatly increased due to the disordered grain structure.

4Cr13 stainless steel, also known as 420HC, is a grade of stainless steel made of composition containing chromium and carbon. It is a higher-carbon version of 420 stainless steel with increased hardness and strength, commonly used for making knives and machete blades.

The stainless steel is martensitic, meaning that it has retained some of its original austenite structure. As a result, it has a poor ductility, poor weldability and poor toughness. However, its high carbon content makes it very hard and wear resistant, making it a good choice for use as a blade material.

The metal has undergone cryogenic treatment, a process of cooling the metal during the tempering process. This helps to increase the hardness and improve the wear resistance of the metal. The metal is often quenched, a process of rapidly cooling the metal after hardening to improve its toughness.

Stainless steel 4Cr13 is typically heat treated to a hardness of 54-56HRC and is highly wear resistant. It is also corrosion resistant and rust resistant, making it a long lasting and durable material suitable for making a blade.

In a metallographic analysis of the metal, a golden coloured grain structure can be seen. Over the grain boundaries, dark bands of martensite can be seen, indicating that the metal has retained some of its original austenitic properties.