Final heat treatment processing machinery parts
The purpose of the final heat treatment is to improve the mechanical properties of hardness, wear resistance and strength.
1) Quenching: Quenching has hardened and the overall quenching. Wherein the surface hardening due to deformation, oxidation and decarbonization smaller and wider application, but also has a high external surface hardening strength, abrasion resistance, while maintaining good internal toughness, impact resistance and strong advantages. To improve the mechanical properties of the surface hardening of parts, often in need of quenching or normalizing heat treatment such as a preliminary heat treatment. The general process route is: Cutting - Forging - normalizing (annealing) - rough - quenching - semi-finished - surface hardening - finishing.
2) carburizing: carburizing for mild steel and low alloy steel parts to increase the carbon content of the surface layer, the surface layer after quenching to obtain high hardness, and heart Ministry still maintain a certain strength and higher toughness and ductility. Carburizing carburizing points overall and local carburizing. Do not take part to the local carburizing carburizing seepage control measures (or copper plating impervious material). Since the deformation carburizing and carburizing depth is generally between 0.5 ~ 2mm, so the carburizing process is generally arranged between the semi-finishing and finishing. Its process lines generally: Cutting - Forging - normalizing - rough, semi-finish - carburizing - finishing.
When not part of the local carburizing carburizing parts, the use of increased margin after removal of excess process scheme carburized layer removal of excess carburizing layer after carburization step should be scheduled, before quenching.
3) nitriding: the nitriding treatment is to make the nitrogen atoms into the metal surface treatment method to obtain a layer of nitrogen-containing compounds. Nitrided layer can improve the hardness, wear resistance, fatigue strength and corrosion resistance of the surface of the part. Due to the low temperature nitriding treatment, deformation, and the nitrided layer is thin (generally less than 0.6 ~ 0.7mm), and therefore should be after the nitriding step by arrangements were often arranged between finishing. To reduce distortion nitriding time, after cutting the need for general stress relief tempering.
