Cold Work Die Heat Treatment
DATE：2019/9/20 8:40:45 / READ： / SOURCE：This station
Cold work die heat treatment
The heat treatment of the cold working die generally includes two types of preliminary heat treatment and final heat treatment. In addition, there are heat treatment in mold processing, recovery heat treatment in use, and the like.
1. preliminary heat treatment
The preliminary heat treatment mainly includes annealing, normalizing and quenching and tempering. The main purpose is to eliminate the residual structural defects of the blank, facilitate the subsequent hot and cold processing, improve the performance and life.
(1) Normalizing
The purpose of normalizing is to eliminate residual carbide nets of carbon tool steel, alloy tool steel, and to refine uneven sheet pearlite.
(2) Stress relief annealing
The purpose of stress relief annealing is to eliminate the residual stress before quenching or finishing of the mold, or to avoid the naphthalene fracture that occurs when the high speed steel is repaired and quenched.
(3) Spheroidizing annealing
The purpose of spheroidizing annealing is to obtain satisfactory processability and to prepare the structure for quenching. The microstructure obtained has a significant effect on the final toughness, toughness after tempering, distortion, cracking tendency, resistance, and fracture toughness.
(4) tempering
The purpose of quenching and tempering is to obtain fine pearlite and ultrafine carbides, eliminate carbide nets and belts, eliminate residual stress after processing, improve microstructure, facilitate machining, prevent quench cracking and reduce quenching distortion. The hardness after quenching and tempering is generally ≤ 229 HBW.
2 final heat treatment
(1) quenching
The mold should be oxidized and decarburized during quenching, and internal stress and tissue unevenness should be minimized. In order to avoid adverse effects on wear, cracking, fatigue and anti-seizure performance.
(2) tempering
The cold working die should be tempered immediately after quenching, but tempering should avoid tempering in the tempering brittle temperature range.
For high-precision, high-alloy steel molds, in order to improve hardness, stabilize size, reduce the tendency to crack and improve the service life, after quenching, cold treatment of -40 to -80 ° C (dry ice + alcohol coolant) or -180 ° C can be used. (Time is 80-120min). In order to reduce the internal stress of cold treatment, it can be graded and cooled. Tempering should be carried out immediately after cold treatment.
The heat treatment of the cold working die generally includes two types of preliminary heat treatment and final heat treatment. In addition, there are heat treatment in mold processing, recovery heat treatment in use, and the like.
1. preliminary heat treatment
The preliminary heat treatment mainly includes annealing, normalizing and quenching and tempering. The main purpose is to eliminate the residual structural defects of the blank, facilitate the subsequent hot and cold processing, improve the performance and life.
(1) Normalizing
The purpose of normalizing is to eliminate residual carbide nets of carbon tool steel, alloy tool steel, and to refine uneven sheet pearlite.
(2) Stress relief annealing
The purpose of stress relief annealing is to eliminate the residual stress before quenching or finishing of the mold, or to avoid the naphthalene fracture that occurs when the high speed steel is repaired and quenched.
(3) Spheroidizing annealing
The purpose of spheroidizing annealing is to obtain satisfactory processability and to prepare the structure for quenching. The microstructure obtained has a significant effect on the final toughness, toughness after tempering, distortion, cracking tendency, resistance, and fracture toughness.
(4) tempering
The purpose of quenching and tempering is to obtain fine pearlite and ultrafine carbides, eliminate carbide nets and belts, eliminate residual stress after processing, improve microstructure, facilitate machining, prevent quench cracking and reduce quenching distortion. The hardness after quenching and tempering is generally ≤ 229 HBW.
2 final heat treatment
(1) quenching
The mold should be oxidized and decarburized during quenching, and internal stress and tissue unevenness should be minimized. In order to avoid adverse effects on wear, cracking, fatigue and anti-seizure performance.
(2) tempering
The cold working die should be tempered immediately after quenching, but tempering should avoid tempering in the tempering brittle temperature range.
For high-precision, high-alloy steel molds, in order to improve hardness, stabilize size, reduce the tendency to crack and improve the service life, after quenching, cold treatment of -40 to -80 ° C (dry ice + alcohol coolant) or -180 ° C can be used. (Time is 80-120min). In order to reduce the internal stress of cold treatment, it can be graded and cooled. Tempering should be carried out immediately after cold treatment.
Author：admin