Heat treatment method of cold drawn seamless carbon steel pipe

Posted by zora li on November 14th, 2022

Heat treatment of cold drawn seamless carbon steel pipe:

Cold-drawn seamless pipe are used for fine surface treatment of precision mechanical structures, hydraulic equipment and cold-drawn or cold-rolled precision seamless pipes. High wire drawing accuracy, strict diameter and dimensional accuracy (tolerance), and good outer surface finish, roundness, flatness, and thickness uniformity.

(1) Annealing of cold-drawn steel: refers to the heat treatment process of heating the metal material to an appropriate temperature, holding it for a certain period of time, and then slowly cooling it. Common annealing processes include recrystallization annealing, stress relief, spheroidizing annealing, and full annealing. The main purpose of annealing is to reduce the hardness of metal materials, improve plasticity, cut off Harix pressure processing, reduce residual stress, improve the uniformity of structure and composition, and can be heat treated or prepared.

(2) Ordinary cold-drawn steel: refers to the air-cooling heat treatment process in which the steel or AC3 or ACM steel is heated (the critical temperature of the steel) over 30-50°C and maintained for an appropriate time. The purpose of normalizing is to improve the mechanical properties, processability, grain refinement, and elimination of structural defects of low-carbon steel, and to prepare for the heat treatment and post-structure of low-carbon steel.

(3) Quenching of cold drawn steel: heating at a temperature higher than Ac3 or Ac1 (the lower critical temperature of steel), and then cooling at an appropriate rate to obtain martensite (or shell heat treatment structure). Common salt bath quenching processes include martensitic quenching, surface quenching and partial quenching isothermal quenching. The purpose of quenching is to obtain martensitic steel to improve the hardness, strength and wear resistance of the workpiece, and to prepare for the heat treatment after the organization.

(4) Tempering of cold drawn steel: quench the steel, then heat it to a temperature below Ac1, heat it for a certain period of time, and then cool it to room temperature for heat treatment. Tempering common grinding, tempering, tempering and repeated grinding. The purpose of tempering is to eliminate the stress produced by quenched steel, which has higher hardness, wear resistance, plasticity and toughness.

(5) Quenching of cold drawn steel: refers to the heat treatment quenching and tempering of steel or composite steel. For quenched and tempered steel. Generally refers to the carbon structure of carbon steel and alloy steel.

(6) Chemical treatment of cold-drawn steel: It refers to the heat treatment of metal or alloy workpieces in a constant temperature medium, and one or several elements are added to the surface to change its chemical composition, microstructure and heat treatment process performance. Common chemical heat treatment processes are: carburizing, nitriding, carbonitriding, and aluminizing. The purpose of chemical treatment is to improve the surface hardness, wear resistance, corrosion resistance, fatigue resistance and oxidation resistance of steel.

(7) Cold-drawn molten steel treatment: The alloy is heated to a high temperature single-phase region, and the constant temperature is maintained to completely dissolve the phase and quickly dissolve into a solid solution. The supersaturated solid solution heat treatment process is obtained. The purpose of solution treatment is to improve the toughness and toughness of steel and to prepare precipitation hardening alloys.

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