Metallographic diagram of 20CrMnTi (quenched and tempered at low temperature after carburizing at 910°C)

20CrMnTi(910℃ carburizing followd by tempering and low temperature annealing) is a type of medium carbon alloy steel which is widely used for various purposes. It has good strength, ductility, fatigue resistance and hardness after heat treatment. The basic composition of the alloy include 20% Chromium, 1% Manganese and 0.5% Titanium.

20CrMnTi(910℃ carburizing）is a process of case hardening a steel part in which nitrogen or carbon is added to the external surface. In this process, the steel part is exposed to a carbon-saturated fluid at a specified temperature. This process hardens the exterior while the inner core remains soft, making the part strong and durable enough to withstand high amounts of stress and friction.

The 910℃ carburizing treatment of the 20CrMnTi alloy brings a variety of benefits. When the part is exposed to this type of heat treatment, its surface hardness increases, as does its wear and tear resistance. It also has improved corrosion resistance against aggressive environments. In addition, it has better impact resistance and fatigue strength.

To complete the heat treatment of 20CrMnTi(910℃ carburized), tempering and low temperature annealing should be done. The tempering process helps the alloy to achieve the desired hardness, toughness and strength. It also softens the steel and increases its ductility. Low temperature annealing helps to reduce internal stress levels and improve the machinability of the alloy.

In terms of its microstructure, 20CrMnTi(910℃ carburizing, tempering and low temperature annealing) exhibits a martensitic-bainitic matrix of microstructure. This microstructure is composed of bainite at the core, which makes the alloy strong and wear resistant. The small, dispersed primary carbides around the bainite also increase wear resistance. Martensite is also present at the carburized surface, further increasing its wear resistance. Lastly, the small and distributed secondary carbides are beneficial for providing impact resistance and corrosion resistance.

To summarize, 20CrMnTi(910℃ carburizing followed by tempering and low temperature annealing is a high-performance medium carbon alloy steel with excellent properties including high strength, good ductility, fatigue resistance and improved wear resistance, corrosion resistance and impact resistance. Its microstructure is composed of a bainitic-martensitic matrix with dispersed primary carbides and small secondary carbides to improve its strength and wear resistance.

The 20CrMnTi steel is a typical alloy medium carbon quenching and tempering hardened steel. After carbon penetration at 910℃ and quenching, the 20CrMnTi steel was subjected to a low temperature tempering process to improve its mechanical properties and durability. The microstructure of the 20CrMnTi steel after the process is characterized by a tempering structure of a mixture of lath martensite and spheroidized ferrite which form a tempered martensite matrix. The lap martensite structures show a fine structure with the majority of the laths having width range of 0.5-5 μm. The chromium carbides are mostly in a non-intersecting network distribution shape with a mean size range of 5- 9 μm. The small amount of ferrite is distributed around the lath martensite in a fringed pattern, with a small amount of spherical pearlite interspersed. Finally, there is a small amount of retained austenite, with a size of 1-2 μm. This microstructure of the 20CrMnTi steel is complex and has excellent mechanical properties, making the steel suitable for a wide range of uses.