Safety Apparel,Protective Apparel,Reflective Safety Vest Jinyang Industrial Corporation., Ltd. , http://www.dmreflectives.com
(2): Normalizing: refers to a heat treatment process in which steel or steel is heated to 30 to 50 ° C above Ac3 or Acm (the upper critical point temperature of steel) and kept in a static air for a suitable period of time. The purpose of normalizing is to improve the mechanical properties of low carbon steel, improve the machinability, refine the grains, eliminate the defects of the structure, and prepare the tissue for the subsequent heat treatment.
(3): quenching: refers to heating the steel to a temperature above Ac3 or Ac1 (the lower critical temperature of the steel) for a certain period of time, and then obtaining martensite (or bainite) at an appropriate cooling rate. The heat treatment process of the tissue. Common quenching processes include salt bath quenching, martensite quenching, bainite austempering, surface quenching and partial quenching. The purpose of quenching: to obtain the desired martensite structure of the steel, improve the hardness, strength and wear resistance of the workpiece, and prepare the structure for the subsequent heat treatment.
(4): Tempering: refers to the heat treatment process in which the steel is hardened to a certain temperature below Ac1, kept for a certain period of time, and then cooled to room temperature. Common tempering processes are: low temperature tempering, medium temperature tempering, high temperature tempering and multiple tempering. The purpose of tempering: mainly to eliminate the stress generated by the steel during quenching, so that the steel has high hardness and wear resistance, and has the required plasticity and toughness.
(5): tempering: refers to the composite heat treatment process of quenching and tempering steel or steel. Steel used for quenching and tempering is called quenched and tempered steel. It generally refers to medium carbon structural steel and medium carbon alloy structural steel.
(6): Chemical heat treatment: refers to the heat treatment process in which a metal or alloy workpiece is placed in an active medium at a certain temperature to infiltrate one or more elements into its surface layer to change its chemical composition, structure and properties. Common chemical heat treatment processes include carburizing, nitriding, carbonitriding, aluminizing, and boronizing. The purpose of chemical heat treatment: mainly to improve the hardness, wear resistance, corrosion resistance, fatigue strength and oxidation resistance of steel parts.
(7): Solution treatment: refers to the heat treatment process in which the alloy is heated to a high temperature single-phase zone to maintain the temperature, and the excess phase is sufficiently dissolved in the solid solution and then rapidly cooled to obtain a supersaturated solid solution. The purpose of solution treatment is to improve the plasticity and toughness of steel and alloy, and prepare for precipitation hardening treatment.
(8): Precipitation hardening (precipitation strengthening): refers to a heat treatment process in which a metal is dispersed in a solute atom in a supersaturated solid solution and/or a solution is obtained by dissolving the particles dispersed in the matrix to cause hardening. For example, austenitic precipitated stainless steel can be subjected to precipitation hardening treatment at 400 to 500 ° C or 700 to 800 ° C after solution treatment or after cold working, and high strength can be obtained.
(9): Aging treatment: refers to the heat treatment process in which the alloy workpiece is subjected to solution treatment, cold plastic deformation or casting, and after forging, at a higher temperature or at room temperature, and its performance, shape and size change with time. If the aging treatment process is used to heat the workpiece to a higher temperature and aging for a long time, it is called artificial aging treatment. If the workpiece is placed at room temperature or under natural conditions for a long time, the aging phenomenon occurs as natural. Aging treatment. The purpose of aging treatment is to eliminate the internal stress of the workpiece, stabilize the structure and size, and improve the mechanical properties.
(10): Hardenability: refers to the characteristics of determining the hardening depth and hardness distribution of steel under specified conditions. The hardenability of the steel is good and poor, and it is usually expressed by the depth of the hardened layer. The greater the depth of the hardened layer, the better the hardenability of the steel. The hardenability of steel depends mainly on its chemical composition, especially the alloying elements and grain size with increased hardenability, heating temperature and holding time. The steel with good hardenability can obtain uniform and uniform mechanical properties of the whole section of the steel and quenching agent with small quenching stress of steel parts to reduce deformation and cracking.
(11): Critical diameter (critical harden diameter): The critical diameter refers to the maximum diameter of the steel when it is quenched in a certain medium, and the core is all martensite or 50% martensite. The diameter can generally be obtained by a hardenability test in oil or water.
(12): Secondary hardening: Some iron-carbon alloys (such as high-speed steel) must be tempered several times before further increasing their hardness. This hardening phenomenon, called secondary hardening, is due to the precipitation of special carbides and/or due to the transformation of austenite into martensite or bainite.
(13): temper brittleness: refers to the embrittlement phenomenon in which the quenched steel is tempered in certain temperature ranges or slowly cooled from the tempering temperature. The temper brittleness can be divided into the first type of temper brittleness and the second type of temper brittleness. The first type of temper brittleness, also known as irreversible temper brittleness, occurs mainly when the tempering temperature is 250-400 ° C. After the reheating brittleness disappears, the tempering in this interval is repeated, no brittleness occurs, and the second type of tempering Brittleness, also known as reversible temper brittleness, occurs at temperatures between 400 and 650 ° C. When reheating and brittleness disappears, it should be cooled rapidly. It should not stay in the interval of 400-650 ° C for a long time or slow cooling, otherwise the catalytic phenomenon will occur again. The occurrence of temper brittleness is related to the alloying elements contained in steel. For example, manganese, chromium, silicon, and nickel have a tendency to temper brittleness, while molybdenum and tungsten have a tendency to weaken temper brittleness.
Several ways of heat treatment
(1): Annealing: A heat treatment process in which a metal material is heated to an appropriate temperature for a certain period of time and then slowly cooled. Common annealing processes are: recrystallization annealing, stress relief annealing, spheroidizing annealing, complete annealing, and the like. The purpose of annealing: mainly to reduce the hardness of metal materials, improve plasticity, to facilitate cutting or pressure processing, reduce residual stress, improve the homogenization of tissue and composition, or prepare the tissue for the subsequent heat treatment.