Heat Treatment Method and Solution for Quenching Deformation of Mud Pump Cylinder Liner

Heat treatment method of mud pump cylinder liner

1. Normalizing (eliminating internal stress and improving hardness) 800℃ for 4-5h air-cooled;

2. Annealing (softening) at 980℃ for 5-6h and furnace cooling;

3. Quenching (hardening) at 980℃ for 30 minutes and air-cooling;

4. Tempering (improving the toughness of the material) maintained at 200℃ for 60 minutes;

5. Hot installation: burned at 450-500℃ for 5-6 hours, checked 100% complete, and pressure tested after cooling for 24 hours.

How to prevent deformation during quenching of mud pump cylinder liner processing?

In the operation of the mud pump used in oil drilling, due to the wear of the sand particles and the corrosion of the medium in the high-speed flowing mud, it is easy to cause damage, grooves, peeling, leakage, cylinder detachment and breakage of the liner.

In order to improve the wear resistance and corrosion resistance of the liner, CR26 high-chromium cast iron blanks are used. After annealing, processing, quenching and low-temperature tempering, the hardness of the blank is required to be greater than HRC62.

However, due to the thin wall thickness of the liner (6=5.5 mils, 7 mils), 100% of the mud pump cylinder liners have different degrees of deformation during the heat treatment process and cannot meet the assembly requirements. An additional forming process is required, which not only increases the processing cost, but also causes cracking and scrapping of some liners due to excessive shaping.

To prevent the deformation during quenching of the mud pump cylinder liner, the following methods can be adopted:

First, to prevent deformation during quenching of the mud pump cylinder liner, lower heating temperature (980℃) and lower cooling rate (air cooling) should be used as much as possible. When the hardness requirement is HRC>60, Cr26 high-chromium cast iron material can meet the above process with a CrC ratio of 8.9-9.6.

Secondly, in order to prevent the structure, shape and cooling conditions of the basket from affecting the workpiece, the workpiece should be removed from the basket as soon as possible to disperse and cool while avoiding deformation caused by high-temperature clamping. Therefore, the temperature range of the workpiece removed from the hanging basket should be controlled. Due to the repeated heating and cooling of the wire mesh basket, the welded support beams on the wire mesh basket will deform. Therefore, regular inspections should be carried out on the flatness of the edge of the support beam and processed by the process to keep it within the allowable tolerance range.

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