Practice of heat treatment of Wuhan Handern Steel
DATE：2020/5/8 8:20:01 / READ： / SOURCE：This station
Practice of heat treatment of Wuhan Handern Steel
1.1 Annealing of steel www.handern.com meltblown non-woven equipment
Steel annealing is a heat treatment process that heats steel parts to an appropriate temperature for a certain period of time and then slowly cools down. www.handern.com Meltblown non-woven equipment
The main purpose of steel annealing is: www.handern.com meltblown non-woven equipment
1) Reduce the hardness of steel parts to facilitate subsequent cutting. Generally speaking, the hardness range of steel parts suitable for cutting is between 160 and 230 HBW. www.handern.com Meltblown non-woven equipment
2) Eliminate the residual stress generated after casting or forging to stabilize the size of steel parts and prevent distortion and cracking. www.handern.com Meltblown non-woven equipment
3) Make the chemical composition uniform, refine the grains, improve the structure, and improve the mechanical and technological properties of the steel. 4) Prepare the organization for the final heat treatment (quenching and tempering). www.handern.com Meltblown non-woven equipment
1. Annealing process methods The commonly used annealing processes in production are: complete annealing, incomplete annealing, isothermal annealing, spheroidizing annealing, stress relief annealing, white spot prevention annealing, homogenization annealing, recrystallization annealing, etc. www.handern.com Meltblown non-woven equipment
(1) Complete annealing is an annealing process that a steel piece is fully austenitized and then slowly cooled to obtain a near-balanced structure. The key points of the complete annealing process of hypoeutectoid steel are: the austenitizing temperature is selected at Ac3 + (30 ～ 50) ℃, and then slowly cooled after heat preservation. For some high-alloy steels, in order to make the solid solution of carbides, the austenitizing temperature can be appropriately increased and fully annealed. It is mainly used for the casting and welding of carbon steel and alloy steel with medium carbon content (0c is 0.3% to 0.6%). Forging and rolling parts can also be used for annealing before quenching and rework of high speed steel and high alloy steel. Its main purpose is to refine the structure, reduce hardness, improve cutting performance and eliminate internal stress. www.handern.com Meltblown non-woven equipment
(2) Incomplete annealing is an annealing process in which steel parts are austenitized and then slowly cooled. The main points of the incomplete annealing process are: heating to Ae1 + (30 ～ 50) ℃, and slowly cooling after heat preservation. Incomplete annealing is mainly used for forging and rolling of medium and high carbon steel and low alloy steel without coarsening grains. Its main purpose is to reduce hardness, improve cutting performance, and eliminate internal stress.
(3) Isothermal annealing is to heat the steel to a temperature higher than Ae3 (or Ae), after maintaining for an appropriate time, cool to the appropriate temperature in the pearlite transformation temperature range quickly and maintain it isothermally, so that the austenite transformation lattice Ae + (30 ～ 50) ℃ (hypoeutectic steel) or Ao + is the annealing process of pearlite structure and cooling in air. www.handern.com Meltblown non-woven equipment
(4) Spheroidizing annealing is an annealing process performed to spheroidize carbides in steel. The annealing time of gold steel) to improve the bio-spheroidizing annealing process is: heating to Ae + (10-20) ℃ (eutectoid or hypereutectoid steel) or A- (20-30) ℃ (cold extrusion of structural steel) After the heat preservation, isothermal cooling (slightly lower than the Ar temperature) becomes slow cooling. Spheroidizing annealing is mainly used for forging and eutectoid carbon steel and alloy steel, rolling parts such as carbon tool steel, alloy tool steel, rolling bearing steel, etc., and cold extruded parts of structural steel. The main purpose of spheroidizing annealing of steel parts: In addition to the purpose usually achieved by annealing, the carbon body (or carbide) in the steel should be spherical to reduce hardness, improve plasticity, improve cutting machinability, and The following fires are well prepared for organization. Before the spheroidization meets fire, the metallographic structure should be examined. If there is a serious carbon (or carbide) network on the original structure, it should be eliminated by normalizing process before spheroidizing annealing. www.handern.com Meltblown non-woven equipment
(5) Stress relief annealing is an annealing process to remove the internal stress caused by plastic deformation, cutting or welding of the workpiece and the residual stress surface existing in the casting. The main points of the stress relief annealing process are: heating to Aa1- (100-200) ℃ (generally 500-650 ℃) after holding and slow cooling. Stress relief annealing is mainly used to eliminate residual stress in castings, forgings, welded parts, cold stamping parts and machined workpieces. In order to avoid the rabbit from causing distortion or cracking in the subsequent mechanical processing, heat treatment or long-term use. For some large welding objects in engineering. Due to the large volume, it is impossible to anneal in the furnace. Local heating (or flame, induction, far infrared radiation, etc.) can be used to perform local stress relief annealing of the welded joint. www.handern.com Meltblown non-woven equipment
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