CBIES AUTOMOTIVE|In-depth Understanding Of The Difference Between Annealing And Normalizing
We all know that some tube process treatment needs to do annealing and normalizing some action. Annealing and normalizing are widely used in the preparatory heat treatment process, mainly used to improve the cutting and machining properties of the material. CBIES AUTOMOTIVE is a professional auto parts export enterprise, deep into the steel tube manufacturing industry for many years, the product contains various tube products, precision welded tubes, precision seamless tubes, etc. For annealing and the normalizing process is also essential. Here to take you to understand the difference between annealing and normalizing of pipe fittings.
Annealing is a metal heat treatment process in which the metal is slowly heated to a certain temperature, held for a sufficient time, and then cooled at a suitable rate. Annealing heat treatment is divided into complete annealing, incomplete annealing, and stress relief annealing. The mechanical properties of annealed materials can be tested by tensile tests and also by hardness tests. Many sheets of steel are supplied in annealed heat treatment conditions. Steel hardness testing can be done with a Rockwell hardness tester to test HRB hardness, and for thinner steel plates and strips as well as thin-walled steel pipes, a surface Rockwell hardness tester can be used to test HRT hardness.
The main differences between annealing and normalizing.
A. Normalizing cooling rate is slightly faster than annealing, and the subcooling degree is larger
B. Normalized to obtain a finer organization, strength and hardness are higher than annealed.
Choice of annealing and normalizing.
A. For low-carbon seamless steel pipe with a carbon content of less than 0.25%, normalizing is usually used instead of annealing. Because the faster cooling rate can prevent the low carbon seamless steel tube along the grain boundary precipitation of free three carburized body, thus improving the cold deformation performance of the stamping; normalizing can improve the hardness of steel and low carbon seamless steel tube cutting performance. In the absence of other heat treatment processes, normalizing can refine the grain and improve the strength of low-carbon seamless steel pipe.
B. Medium carbon cold-drawn seamless steel tubes with a carbon content between 0.25% and 0.5% can also be normalized instead of annealing. Medium carbon steel cold-drawn seamless steel tubes with carbon content close to the upper limit can be cut despite their high hardness after normalizing, with low normalizing cost and high productivity.
C. Cold-drawn seamless steel pipe with a carbon content between 0.5-0.75%, due to the high carbon content, the hardness after normalizing is significantly higher than annealing, making it difficult to carry out cutting, so complete annealing is generally used to reduce hardness and improve machinability.
D. Cold-drawn seamless steel pipe with carbon content > 0.75% of high carbon or tool steel is generally used for spheroidal annealing as the initial heat treatment. If there is a network of secondary carburized bodies, should be normalized first. Annealing is a heat treatment process in which the cold-drawn seamless steel tube is heated to an appropriate temperature, held for a certain period of time, and then slowly cooled. Slow cooling is the main feature of annealing. Annealed cold-drawn seamless steel pipe is generally cooled with the furnace to below 550°C and air-cooled. Annealing is a widely used heat treatment. In the manufacturing process of tools, molds or mechanical parts, etc., it is often arranged after casting, forging, and welding, and before cutting (rough) machining as a preliminary heat treatment to eliminate some of the problems caused by the previous process. defects, and to prepare for subsequent operations.
Annealing Purpose:
a. Improve or eliminate various structural defects and residual stress caused by steel during casting, forging, rolling, and welding, and prevent workpiece deformation and cracking;
b. soften the workpiece for cutting;
c. Refine the grains, improve the structure, and improve the mechanical properties of the workpiece;
d. Prepare the structure for final heat treatment (quenching, tempering).
