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Purpose This study aims to the service life of TA15 alloy by solving the problem of the binding force between the matrix and AlTiSiN coating. The effect of a plasma nitriding (PN) interlayer on the magnetron-sputtered AlTiSiN coating was also investigated in detail. Design/methodology/approach The double-glow plasma alloying (DGPA) and magnetron sputtering (MS) techniques were combined as a new approach to realize a bilayer on TA15 consisting of an AlTiSiN layer with a PN interlayer. A TiN interlayer was formed via co-diffusion during the PN conducted at 1050°C for 3 h. Findings The PN interlayer can effectively improve the adhesion between coating and matrix; the PN/AlTiSiN coating presented excellent adhesion (80.1 N) and anti-wear property with a nano-hardness of 18.62 GPa. The resulting three-dimensional wear-track morphology exhibited a shallow depth and a narrow width. Originality/value The novel combination of the DGPA and MS technologies, using an infiltration layer rather than a coating one as the intermediate layer, can effectively enhance the adhesion between AlTiSiN coating and TA15 matrix. Meanwhile, the gradient layer can effectively improve both surface bearing and wear resistance.

Trace and fracture analysis, metallographic examination, residual stress testing, and material analysis were carried out, coupled with examining the failure timeline, to analyze the cracking problem of 12CrNi3A steel counterweight blocks under multi-factor coupling. The results show that the cracks of the counterweight blocks are intergranular microcracks in the carburized layer and they are delayed cracks under the joint action of microstructure stress, grinding stress and hydrogen. The delayed cracking of the counterweight blocks is mainly related to abnormal hydrogen absorption during surface treatment and poor grinding quality. The obvious microstructure segregation in raw material and the thicker carburized layer promoted the cracking. The following measures should be comprehensively taken to prevent such failure: strictly controlling raw material quality, hydrogen absorption and stress, as well as increasing the processes to remove hydrogen, reduce stress and stabilize microstructure.