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Heat treatment
- Jun 24, 2018 -

We know that production of machine knife like ice resurfacing blade cannot be without heat treatment? Then what is heat treatment?

Heat treatment is a kind of metal heat treatment process in which the material can obtain the expected structure and performance through heating, heat preservation and cooling in solid state. In the course from the Stone Age to the Bronze Age and the iron age, the role of heat treatment has been gradually recognized.

As early as 770 BC to 222 BC, Chinese people have found in their production practice that the performance of steel can be affected by temperature and pressure deformation. The softening treatment of white cast iron is an important process for making farm tools.

1. Normal fire: the steel or steel parts are heated to AC3 or ACM above the critical point at an appropriate temperature and cooled in the air for a certain period of time.

2. Annealing annealing: hypoeutectoid steel workpiece heated to above AC3 20 to 40 degrees, heat preservation after a period of time, with the slow cooling furnace (or buried in the sand or lime cooling) to 500 degrees Celsius in air cooling heat treatment process. 3. Solid solution heat treatment: the alloy is heated to a high temperature single-phase zone and kept at constant temperature, so that the excess phase is fully dissolved into the solid solution, and then cooled quickly to obtain the heat treatment process of oversaturated solid solution. 4. Aging: the properties of the alloy change with time when it is placed at room temperature or slightly above room temperature after solid solution heat treatment or cold plastic deformation. 5. Solid solution treatment: make the various phases in the alloy dissolve sufficiently, strengthen the solid solution, improve toughness and corrosion resistance, eliminate stress and soften, so as to continue processing and forming. 6. Aging treatment: heat and keep warm at the temperature of the precipitated phase, so that the precipitated phase can be hardened and the strength can be improved. 7. Quenching: a heat treatment process in which the austenitic steel is melted and cooled at an appropriate cooling rate so that the workpiece can undergo structural transformation of unstable structures such as martensite in a whole or a certain range of cross-sections. 8. Heated to a critical point to tempering after quenching workpiece AC1 under proper temperature keeping time, method of cooling, then used to meet the requirements for the organization and performance of the heat treatment process required. 9. Carbonitriding of steel: carbonitriding is the process of simultaneously infiltrating carbon and nitrogen into the surface of steel. Traditionally, carbonitriding is also known as cyanide, which is widely used for medium temperature gas and low temperature gas carbon nitriding (i.e., gas soft nitriding). The main purpose of medium temperature gas carbonitriding is to improve the hardness, wear resistance and fatigue strength of steel. The main purpose of low temperature gas carbonitriding is to improve the wear resistance and bite resistance of steel. 10. Quenching and tempering: the heat treatment which combines quenching and tempering is usually called quenching treatment. Conditioning is widely used in all kinds of important structural parts, especially connecting rods, bolts, gears and shafts that work under alternating loads. After the tempering treatment, the tempered soxhlet structure was obtained. Its hardness depends on high temperature tempering temperature and is related to steel tempering stability and workpiece section size, generally between hb200-350.