Process analysis of quenching heat treatment using medium frequency induction heating machine for inlaid steel guide rails

The material of the steel-inlaid guide rail is T8 steel. Heat treatment technical requirements: The hardness of the working surface of the guide rail is 60-65HRC, the depth of the hardened layer is >1.5mm, and there should be no soft spots or cracks on the quenched surface. In order to meet the above requirements, many manufacturers use medium frequency induction heating machines for quenching heat treatment, with good results.

(1) Sensor

The guide rail quenching sensor is made of 10mm×10mm special-shaped pure copper tube. The gap between the sensor and the guide rail surface is controlled at 2.5mm-3mm to ensure uniform heating of the sensor and cooling by water spray.

(2) Heat treatment process

1) Preparation for heat treatment. Preparatory heat treatment prepares the structure for induction quenching, reduces quenching distortion, and improves the performance of the guide rail. The preparatory heat treatment of T8 steel adopts spheroidizing annealing.

2) Induction hardening process of inlaid steel guide rails. The working surface of the inlaid steel guide rail is hardened using a medium frequency diathermy furnace and water spray cooling method. The specific process parameters are shown in the table below.

(3) Inspection results. The hardness of the working surface of the guide rail is 62-65HRC, the depth of the hardened layer is 2.8mm, and the bending distortion is 0.55-0.60mm, all of which meet the technical requirements.