A brief analysis of the specific process of heat treatment using medium frequency induction heating power for steel-inlaid machine tool guide rails

The material of the steel-inlaid machine tool guide rail is GCr15 steel, and the heat treatment technical requirements are: surface hardness is 62-64HRC, and distortion is <0.5mm. In order to meet the above requirements, many manufacturers use medium frequency induction heating power for heat treatment, with good results.

(1) Process flow. Forging - quenching and tempering - machining - preheating, quenching - tempering - hot spot correction - rough grinding - stress relief and tempering - fine grinding.

(2) Heat treatment process

1) Change the conventional spheroidizing annealing after forging to quenching and tempering treatment to obtain uniformly distributed dispersed fine carbides and fine-grained sorbite structure, and reduce the distortion caused by volume changes during the quenching process.

2) The guide rail is long in size and its effective thickness exceeds the critical diameter of oil quenching. After regular quenching and tempering, uneven hardness is likely to occur. In this regard, the quenching temperature was increased from 850°C to 880°C. Not only did the hardness meet the requirements, but also due to the increase in quenching temperature, the Ms point decreased and the amount of retained austenite in the guide rail increased, providing favorable conditions for subsequent corrections. Pre-cooling and quenching reduces the temperature difference between the guide rails and effectively reduces thermal stress. It is beneficial to the thermal correction of the guide rails after the oil is discharged at 240°C, and a small amount of lower bainite may appear, which is beneficial to improving the performance of the guide rails.

3) In order to prevent the stabilization of austenite, cold treatment should be carried out in time to prevent distortion and effectively improve the stability of the shape and size of the guide rail. The hardness is increased by about 2HRC, and the wear resistance is also improved. The guide rail distortion is <0.2mm.

Many manufacturers use the above process for heat treatment, and the produced guide rails are of good quality, with improved hardness, wear resistance and service life, meeting the needs of the work.