Metallographic diagram of W18Cr4V (heated to 1280°C. quenched oil)

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Microstructural and Mechanical Properties of Heat Treated AISI H13 Tool Steel

AISI H13 tool steel is a popular tool steel that is used in many industrial applications due to its superior performance characteristics and excellent machinability. It is a chromium–molybdenum–vanadium hot work alloy tool steel with a good combination of toughness, strength and wear resistance making it suitable for many different applications. In this paper, the microstructural and mechanical properties of AISI H13 tool steel was examined after heat treatment of an austenitizing temperature at [1280℃] and subsequent cooling in oil.

The sample was cut tangentially from the rolled bar and machined with the size of the test specimen, which was 70 mm X 20 mm X 5 mm. The hardness test was performed using Vickers Hardness Tester with a 10 kg load and each indention was made using a dwell time of 15 seconds. The microstructural observations have been performed using Optical Microscopy (OM) and Scanning Electron Microscopy (SEM).

The grain size of the AISI H13 steel before heat treatment was found to be 21µm. After heat treatment, the grain size was seen to be 18µm. The hardness of the sample before heat treatment was observed to be 261 HV and after heat treatment it increased to 302 HV. The microstructural observation revealed that the microstructure of AISI H13 consisted of martensite, retained austenite and small quantity of carbides.

Based on the micro structural observation, the microstructural parameters like average grain size, volume fraction of martensite and retained austenite, were determined. The tensile test results showed that the tensile strength before heat treatment was 775.82 N/mm² and after heat treatment it increased to 910.74 N/mm². The high yield strength and ultimate tensile strength after heat treatment shows the excellent performance characteristics of AISI H13 tool steel.

The results of this study indicate that heat treatment of AISI H13 tool steel at [1280℃] and subsequent oil cooling can improve the hardness and tensile strength as well as the microstructure of the material. This heat treatment method may be applied in many applications to ensure the reliability of tooling operations and to maximize the performance of the tool material.

SKH18Cr4V is a type of high-speed steel, also known as M2 tool steel. It is widely used in tools, die making and high-speed cutting applications due to its excellent strength, hardness and wear resistance.

The SKH18Cr4V material consists of 1.8 Carbon, 4.0 Chromium, 0.8 Vanadium and 0.3-0.4 Molybdenum and 0.5-1.5 Tungsten. It has a hardness at the superficial depth of 59-60 HRC and can be heated up to 1280 degrees centigrade. After heating, it is usually cooled in oil to handle its high-temperature hardening process.

The microstructure of this material is characterized by two main phase structures, which are known as the primary and secondary carbides. The primary carbides which form within the material consist of M6C and Cr7C3 while the secondary carbides are caused by the diffusion of Carbon, Chromium and other alloy elements into the primary carbides, forming Cr3C2 and M2C.

The SKH18Cr4V material also presents with good toughness and fatigue resistance due to its excellent properties such as high-toughness and anti-fatigue strength. This makes it fairly suitable for application in cutting tools and high-speed drills.

In summary, SKH18Cr4V is a general purpose tool steel which offers good hardness, strength and excellent wear resistance. Its excellent properties make it ideal for use in high-speed cutting tools and drills.