Heat treated tool

Austenitizing High Heat : Heat slowly from the preheat. Soak for 30 minutes for the first inch Tempering: Temper immediately after quenching. Hold at temperature for 1 hour per inch To minimize internal stresses in cross sections greater than 6 inches Cryogenic Treatment: Some prefer to do cryogenic treatment as an extension of the quench from the austenitizing treatment.

Others prefer to cryogenically treat after tempering. Grain size is at best a reflection of quenching heating temperature. For cutting tools requiring high red hardness, carbide dissolution degree is more important than grain size. Therefore, when looking at metallography in front of the furnace, both must be taken into account and cannot be neglected. For example, super-hard high-speed steel such as M42 has a suitable range instead of the higher the hardness, the better.

The hardness is too high, not only will it not last long, but be shortened. For a specific tool made of a specific steel grade, there is a practical hardness value under specific working conditions. People have found in practice that high-life cutting tools are generally of high hardness, but those with high hardness do not necessarily have high life.

We should strive for high hardness on the premise of sufficient toughness. The high-quality tool product not only has a high average life but also has stable quality and good repeatability of tool life. The problem of China cutting tools factory is not every tool has a low tool life, but the average tool life is greatly reduced due to the wide difference in tool life and too large dispersion. The stability of product quality and tool life is a comprehensive reflection of a factory's technical level and management level.

It is not easy to make the tool life high. It is a systematic project. From the control of raw materials, mechanical processing, heat treatment, to the final packaging and delivery of products, there must be a set of strict rules and regulations, correct process documents, complete testing methods and good quality of staff.

To sum up, improving cutting tool life requires not only high-quality raw materials, machining level, and strict and fine heat treatment, but also an important determinant of tool life.

To be a world-class cutting tool manufacturer is the direction and mission that Heygo Tools strive all the time. Your email address will not be published. By performing a second temper, this new martensite is softened, thus reducing the chance of cracking.

Tool steels are usually supplied to customers in the annealed condition with typical hardness values around Brinell » 20 HRC to facilitate machining and other operations. This is especially important for forged tools and die blocks where partial or full air hardening takes place, resulting in a buildup of internal stresses. Dies and tools that may need to be rehardened must be annealed.

Full annealing involves heating the steel slowly and uniformly to a temperature above the upper critical temperature Ac3 and into the austenite range then holding until complete homogenization occurs. Cooling after heating is carefully controlled at a specific rate as recommended by the steel manufacturer for the grade of tool steel involved.

The heat-treat process results in unavoidable size increases in tool steels because of the changes in their microstructure. Most tool steels grow between about 0. This varies somewhat based on a number of theoretical and practical factors. Most heat treaters have a feel for what to expect from typical processes.

In certain cases, a combination of variables, including high alloy content, long austenitizing time or high temperature, discontinuing the quench process too soon, inadequate cooling between tempers, or other factors in the process, may cause some of the high-temperature structure, austenite, to be retained at room temperature. In other words, during the normal quench, the structure is not completely transformed to martensite. This retained austenite condition usually is accompanied by an unexpected shrinkage in size and sometimes by less ability to hold a magnet.

This condition often can be corrected simply by exposing tools to low temperatures, as in cryogenic or refrigeration treatments, to encourage completion of the transformation to martensite.

For most tool steels, retained austenite is highly undesirable since its subsequent conversion to martensite causes a size vol-ume increase creating internal stress and leads to premature failure in service. The newly formed martensite is similar to the original as-quenched structure and must be tempered.

Often deep-freezing is performed before tempering due to concerns over cracking, but it is sometimes done between multiple tempers. Retained austenite may be undesirable for a number of reasons. By cooling the steel to cryogenic sub-zero temperatures, this retained austenite may be transformed to martensite. Cryogenic treatments should include a temper after freezing. Heat Treatment of Tool Steels. Schematic tree of metal grouping With a carbon content between 0. Preheating Preheating, or slow heating, of tool steels provides two important benefits.

Austenitizing In general, higher temperatures allow more alloy to diffuse, permitting slightly higher hardness and strength. Tools Steel The actual temperature used depends mostly on the chemical composition of the steel. Chemical Composition The following table list A2 steel chemical composition. Alloy Steel Tool Steel.

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