Nitridation process for worm gear

Abstract

The invention discloses a nitridation process for a worm gear. The nitridation process is characterized by comprising the following steps: (1) clamping a to-be-nitrided worm gear on a special tool, hoisting the to-be-nitrided worm gear to a preheated cleaning pool for cleaning via a crane, then directly putting the cleaned to-be-nitrided worm gear into a preheating furnace with a temperature of 300 DEG C, carrying out preheating for 2 h, then heating the preheating furnace to 480 DEG C and carrying out preheating for 2 h; (2) carrying out nitridation which refers to filling of mixed gas consisting of ammonia gas and nitrogen and comprises two phases, wherein in the first phase, the worm gear is maintained at a temperature of 510 to 520 DEG C for 10 h and an ammonia decomposition rate is 18 to 25%, and in the second phase, the worm gear is maintained at a temperature of 510 to 520 DEG C for 10 h, the ammonia decomposition rate is 30 to 50% and cooling in furnace to 200 DEG C and air cooling out of the furnace are successively carried out; and (3) after completion of nitridation, hoisting the worm gear to a post-nitridation cleaning pool for cooling via the crane, then hoisting the worm gear to a hot-water cleaning pool for cleaning in 8 to 10 min, maintaining the worm gear in the hot-water cleaning pool for 10 min and then hoisting the worm gear in the air so as to allow the worm gear to be rapidly dried. The nitridation process is simple, omits a plurality of repeated procedures, improves work efficiency and enables the overall performance of the worm gear to be greatly improved.

Description

technical field [0001] The invention relates to a turbine worm nitriding process. Background technique [0002] Heat treatment nitriding is nitriding and nitrocarburizing of steel at a temperature of 520°C to 570°C in an atmosphere of ammonia + nitrogen or ammonia + methanol + nitrogen. In recent years, there have been various implementation methods for nitriding and nitrocarburizing processes: for example, pre-vacuuming and filling with ammonia, or ammonia + methanol nitriding treatment process; there is also low vacuum heating first, followed by pulse charging Ammonia gas for nitriding and other processes. In the existing hard nitriding technology, the period is generally 24 to 28 hours, and the nitrided layer reaches 0.2 to 0.3mm. During the nitriding process, the nitrogen potential is not easy to control, and the brittle phase is formed due to the high nitrogen potential, which leads to the performance of mechanical parts. decline. Contents of the invention [0003]...

AI Technical Summary

Problems solved by technology

In the existing hard nitriding technology, the period is generally 24 to 28 hours, and the nitrided layer reaches 0.2 to 0.3mm. During the nitriding process, the nitrogen potential is not easy to control, and the brittle phase is formed due to the high nitrogen potential, which leads to the performance of mechanical parts. decline