关键词: 40Cr钢, 锥面, 激光淬火, 淬硬层, 显微组织

Abstract: Quenching process of 40Cr steel conical surface part was researched by using LDF4000-100 semiconductor lasers. Firstly, a closed-loop temperature control system was used to study the laser quenching quality condition of the 40Cr steel plate samples at different temperatures and scanning speeds. On the basis, the multipass quenching scanning tests were carried out according to the size and shape specification of the quenching area of the large conical part. The results show that the technical requirements of the surface quenching are satisfied by selecting the optimal process parameter with the heating temperature of 1400 ℃, scanning speed of 10 mm/s, the amount of overlaps 1.8 mm and 6 turns laser surface hardening and underling the rectangular facular size 17 mm×5 mm vertical incidence cone surface quenching. The microstructure of hardened layer is the small, diffuse and needle-like martensite. Finally, the better application effect has been acquired in the subsequent industrial pilot production.

Key words: 40Cr steel, conical surface, laser quenching, hardened layer, microstructure