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Several common heat treatment concepts

     Normalizing: heating steel or steel parts to the appropriate temperature above the critical point AC3 or ACM for a certain time and then cooling in air to obtain pearlite structure;
Annealing: the hypoeutectoid steel workpiece is heated to 20-40 degrees above AC3, and then cooled slowly in the furnace (or buried in sand or lime) to below 500 degrees and cooled in air after holding for a period of time;
Solution heat treatment: the alloy is heated to high temperature, and the single-phase zone is kept at constant temperature, so that the excess phase is fully dissolved into the solid solution, and then rapidly cooled to obtain the supersaturated solid solution;
box furnace
Aging: after solution heat treatment or cold plastic deformation, the properties of alloy change with time when placed at room temperature or slightly higher than room temperature;
Solution treatment: dissolve all kinds of phases in the alloy, strengthen the solid solution, improve the toughness and corrosion resistance, eliminate stress and softening, so as to continue processing and forming;
Aging treatment: heating and holding temperature at the precipitation temperature of strengthening phase, so that the strengthening phase precipitates, hardens and improves the strength;
Quenching: it is a heat treatment process in which the steel is austenitized and cooled at a proper cooling rate, so that the unstable structure transformation such as martensite occurs in all or a certain range of the cross-section of the workpiece;

Tempering: a heat treatment process in which the quenched workpiece is heated to an appropriate temperature below the critical point AC1 for a certain period of time, and then cooled in a satisfactory way to obtain the required microstructure and properties;

Carbonitriding of steel: carbonitriding is the process of simultaneous infiltration of carbon and nitrogen into the surface of steel. Carbonitriding, also known as cyaniding, is widely used in medium temperature gas carbonitriding and low temperature gas carbonitriding. 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 anti seizing property of steel;

Quenching and tempering treatment: the heat treatment combining quenching and high temperature tempering is generally called quenching and tempering treatment. Quenching and tempering treatment is widely used in various important structural parts, especially those connecting rods, bolts, gears and shafts working under alternating load. The mechanical properties of tempered sorbite are better than that of normalized sorbite with the same hardness. Its hardness depends on the high temperature tempering temperature and is related to the tempering stability of the steel and the cross section size of the workpiece, which is generally between hb200 and 350;

Brazing: heat treatment process in which two kinds of workpieces are bonded together with filler metal.