Details

Autor(en) / Beteiligte

• Yao, Jiawei
• Yan, Fuyao
• Chen, Baofeng
• Yang, Ying
• Xu, Yueming
• Yan, Mufu
• Zhang, Yanxiang

Titel

Dual-strengthening of steel surface and bulk via synergistic effect of plasma nitriding: A case study of M50 steel

Ist Teil von

• Surface & coatings technology, 2021-03, Vol.409, p.126910, Article 126910

Ort / Verlag

Lausanne: Elsevier B.V

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Duplex-hardened M50 steel is used widely for jet engine shaft bearings. To reduce time and cost in duplex hardening, simultaneous plasma nitriding and tempering is performed upon as-solutioned M50 steel in this work. This heat-treating step can achieve high surface hardness and through-hardened core at the same time. Compared with the conventional “tempering + nitriding” method, the one-step heat treating method in this work can significantly increase the nitrided layer thickness by more than 61% and form a high hardness (>1000 HV0.1) layer spanning half of the total nitrided layer, which leads to reduced friction coefficient and improved wear resistance. A comprehensive study of the nitrided layer was carried out by slicing the surface along the diffusing direction. The phase distribution characters along the diffusing direction were investigated by XRD and SEM. A nitrided layer with gradient nano-structure was observed by the TEM, which experimentally explained the observed supersaturation of nitrogen in the sub-surface layer as a result of spinodal decomposition. •Simultaneous plasma nitriding and tempering of M50 achieve high surface hardness along with secondary hardened core.•The nitrided layer thickness is promoted by more than 60% and high hardness (>1100HV) surface layer spans a half.•The high hardness sub-surface layer is caused by the supersaturation of nitrogen induced by spinodal decomposition.•Nano-structured nitrided layer with breakdown of martensite laths is observed associated with spinodal decomposition.