Seamless steel pipe controlled rolling and controlled cooling online process
2014-01-15
Controlling rolling and cooling can reduce alloy consumption and lower production costs, thus being promoted in seamlesssteel pipesproduction, and initially forming various processes such as online normalization, online quenching, and online rapid cooling.
1. Online normalization process
Online normalization, also known as online normalizing, is a process that occurs after the pipe rolling process on the hot rolling production line, allowingsteel pipesfor air cooling or forced cooling within the austenite phase zone to achieve a uniform metallographic structure.
This process includes two phase transformation processes:
1) The blank pipe cools from 1100°C to below 550°C, where austenite in the steel transforms into ferrite + pearlite;
2) The cooled seamlesssteel pipes, after reheating, the ferrite + pearlite in the steel transforms back into austenite.
Through online normalization, it is possible to achieve uniform steel structure and refine grain size; it can also improve the comprehensive mechanical properties of seamlesssteel pipes.
2. Online quenching process
1) Austenitic stainlesssteel pipes
steel pipes, online quenching, also known as online solution treatment, involves dissolving C elements in the austenitic structure to form a single-phase austenitic structure. The solution treatment temperature is generally between 1000-1150°C. Cooling methods can include water, oil, or air cooling.
2) Carbon steel and low alloysteel pipes
, refers to the heat treatment process of directly performing water quenching using residual heat after rolling and then conducting tempering treatment online. This process can greatly save energy.
3. Online rapid cooling process
, based on ultra-fast cooling technology as its core new generation process. It refers to using residual heat after rolling for direct heat treatment following precision rolling; it applies enhanced cooling to rolled austenite so that metal rapidly cools down to near the ferrite phase transformation temperature within a very short time, thereby suppressing the growth of austenite grains and maintaining the hardened state of austenite as much as possible.
. Online rapid cooling has significant effects on improving seamlesssteel pipes's structure, enhancing comprehensive mechanical properties of seamlesssteel pipes, refining surface grains, and improving resistance to fatigue crack propagation.
Shenyang Tengfei Iron Corporation
Shenyang Tengfei Steel Pipe Co., Ltd.
Address: No.6 A 3, No.13 Road, Economic and Technological Development Zone, Shenyang City, Liaoning Province
E-mail:tfwelcome@163.com
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