直缝钢管退火是把钢管加热到一定温度并在此温度下保温，然后缓慢冷却到室温。退火有完全退火、球化退火、去应力退火等几种。

The annealing of a straight steel pipe is to heat the steel pipe to a certain temperature and keep it warm at this temperature, and then slowly cool it to room temperature. There are several kinds of annealing, spheroidizing annealing, stress annealing and so on.

1、将钢管加热到预定温度，保温一段时间，然后随炉缓慢冷却称为完全退火。目的是降低钢的硬度，消除钢中不均匀组织和内应力。

1, the steel pipe is heated to the predetermined temperature, heat preservation for a period of time, and then slow cooling with the furnace is called complete annealing. The purpose is to reduce the hardness of the steel and eliminate the uneven microstructure and internal stress in the steel.

2、把钢管加热到750度，保温一段时间，缓慢冷却至500度下，最后在空气中冷却叫球化退火。目的是降低钢的硬度，改善切削性能，主要用于高碳钢。

2, the steel pipe is heated to 750 degrees, heat preservation for a period of time, slowly cooling to 500 degrees, and finally cooling in the air and called spheroidizing annealing. The purpose is to reduce the hardness of the steel and improve the cutting performance, which is mainly used in high carbon steel.

3、去钢管应力退火又叫低温退火，把钢加热到500～600度，保温一段时间，随炉缓冷到300度以下，再室温冷却。退火过程中组织不发生变化，主要消除金属的内应力。

3, to the steel tube stress annealing also called low temperature annealing, the steel heating to 500~600 degrees, heat preservation for a period of time, with the furnace cold to less than 300 degrees, and then cooling at room temperature. The microstructure does not change during the annealing process, which mainly eliminates the internal stress of the metal.

4、正火将钢管加热到临界温度以上30-50℃,保温适当时间后，在静止的空气中冷却的热处理工艺称为正火。正火的主要目的是细化组织，改善钢的性能，获得接近平衡状态的组织。

4, normalizing the steel tube to the critical temperature above 30-50 degrees C, after the proper time of heat preservation, the heat treatment process of cooling in the static air is called normalizing. The main purpose of the normalizing is to refine the tissue, improve the performance of the steel, and obtain an organization near the equilibrium state.

5、淬火将钢管加热到临界点以上某一温度,保持一定的时间，然后以适当速度在水中冷却以获得马氏体或贝氏体组织的热处理工艺称为淬火。

5, quenching and heating the steel pipe to a certain temperature above the critical point for a certain time, then cooling it in water at appropriate speed to obtain martensitic or bainitic microstructure heat treatment process is called quenching.

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