Heat treatment process for reducing hardness difference of wind power bolt

Abstract

The invention discloses a heat treatment process for reducing the hardness difference of a wind power bolt, which comprises the following steps of: 1, heating the wind power bolt to 880 + / -5 DEG C by adopting a gradient tempering process, and keeping the temperature for 150-180 minutes; secondly, quenching is conducted, and the heat preservation time is controlled to be 98 min to 110 min; 3, sectional type gradient tempering is conducted, the tempering temperature of the first section is 540 + / -5 DEG C, and the heat preservation time is 90-120 min; 4, sectional gradient tempering is conducted, the tempering temperature of the second section is 540 + / -5 DEG C, and the heat preservation time is 90-120 min; 5, sectional gradient tempering is conducted, the tempering temperature of a third section is 565 + / -5 DEG C, and the heat preservation time is 60-90 min; and sixthly, sectional gradient tempering is conducted, the tempering temperature of the fourth section is 565 + / -5 DEG C, and the heat preservation time is 60-90 min. According to the method, the secondary heat treatment cost and the material scrapping loss are reduced, and the core and surface hardness difference of the wind power bolt is reduced.

Description

【Technical field】 [0001] The invention relates to the technical field of a heat treatment process for reducing the hardness difference of wind power bolts, in particular to the technical field of a heat treatment process for reducing the hardness difference of wind power bolts. 【Background technique】 [0002] With the high performance of wind turbines and the increase of material use stress, higher design stress and weight reduction requirements are put forward for bolts. Most of the current wind power high-strength bolts are grade 10.9. In order to ensure the high strength of wind power fasteners, 42CrMo, B7 and other steel grades are usually used to make wind power bolts. However, the control of the parameters of the existing quenching and tempering heat treatment process is relatively rough, and the problems of high surface hardness and low core hardness are prone to occur, resulting in poor core surface hardness, resulting in a core surface hardness difference > 30HV...

AI Technical Summary

Problems solved by technology

However, the control of the existing quenching and tempering heat treatment process parameters is relatively rough, and the problems of high surface hardness and low core hardness are prone to occur, resulting in poor core surface hardness, resulting in core surface hardness difference > 30HV, increasing the fragility of bolts, and easy to break. Need to adopt secondary heat treatment to save, there is also the possibility of scrapping