Process analysis and implementation key points for heat treatment of sucker rods using medium frequency induction heating power

The sucker rod is a key equipment component in oil extraction. During the working process, the sucker rod reciprocates up and down in the oil pipe and bears the effects of asymmetric cyclic alternating loads. Therefore, production requires the sucker rod to have high fatigue resistance and high mechanical strength. In order to meet the above requirements, many manufacturers use medium frequency induction heating power for heat treatment, with good results.

Analysis and implementation key points of medium frequency heat treatment process for sucker rods:

1. The basic principles for determining the heat treatment process parameters are: first, it must be fully austenitized, with an appropriate amount of carbide dissolution and uniform composition. Secondly, the grain size should be controlled above level 6, and the heating temperature and temperature should be determined accordingly. Holding time, this can be accomplished by conducting a series of process tests, and at the same time, the performance of the medium frequency induction heating power supply must be combined to adopt the optimized heat treatment process parameters.

2. Uniform heating and cooling of the sucker rod is the prerequisite to ensure that its mechanical properties are guaranteed. The cooling accumulation and the inability of the cooling medium to circulate during production are very fatal links, especially during the normalizing process of 45 steel. , so in the actual operation process, error correction and preventive measures should be taken to reduce the impact of human factors.

3. After the sucker rod adopts the general normalizing process, it is prone to oxidative decarburization, which will reduce its fatigue life. The purpose of normalizing is to improve the structural defects caused by the rolling and upsetting process of the sucker rod to refine the structure. The purpose of high-temperature tempering is to eliminate the internal stress generated during normalizing and stabilize the structure. Therefore, normalizing and high-temperature tempering are general heat treatment processes for sucker rods, but attention must be paid to protecting the heating.

4. Judging from the mechanical properties of medium-frequency induction heating, penetration normalizing heating and tempering of the sucker rod, it is better than ordinary normalizing. The main reason is that the structure of the parts has been refined, and tissue refinement has unique advantages. , on the one hand, it improves the strength and toughness of the sucker rod, and on the other hand, its fatigue strength is significantly improved. The grain size of medium-frequency induction heating penetration normalizing can be refined to 11-12 levels, and its structure is fine-grained ferrite evenly distributed on pearlite. After normalizing in an electric furnace, the grain size is 6-7 levels, and the structure is composed of It is composed of thicker massive ferrite and pearlite, so the use of medium-frequency induction heating and penetration normalizing is the development direction of process progress.

5. Improper or out-of-control welding and post-weld heat treatment can easily cause sucker rod fracture accidents. Most of the sucker rod fractures occur in the weld and heat-affected zone. The local quenching and tempering treatment of the joint after welding will produce a new heat treatment affected area, which can easily lead to softening and strength reduction of the joint. Therefore, local medium-frequency induction heating and tempering treatment of the weld joint should be carried out, and the temperature should not exceed the conditioning temperature of the base metal before welding. The quality treatment temperature can ensure that the strength and toughness of the joint meet the requirements.

This article briefly introduces the heat treatment process and implementation points of sucker rods. I hope it will be helpful to your work. If you want to know more detailed information, you can read books on heat treatment. I believe you will gain a lot.