Failure Analysis of Chromium Plating Layer on the Surface of the Piston Rod of the Hydraulic Jack

Abstract

The piston rod of the hydraulic jack was a kind of artillery alloy structural steel of 40Cr and its surface was the chromium plating layer. The piston rod worked for a while; the defects of corrosion pit and peeling appeared on the chromium layer. A stereo-microscope, metallographic microscope, and scanning electron microscope (SEM) were used to observe the macromorphology, micromorphology, and microstructure of the failed parts. The composition analysis was performed by the energy dispersive spectroscopy (EDS), and a Vickers hardness tester was used to measure the hardness. The results showed that pores and penetrating cracks existed in the chromium layer, leading to the corrosion medium invading the interface and forming a corrosion source. Then, the corrosion intensified, resulting in the bubbling, cracking, and peeling of the chromium layer. More O and minor S elements were detected in the corrosion pit. Finally, the fracture of the chromium layer was a 45° angle destruction mode. The peeling of the chromium layer was caused by the pores and microcracks, working medium, and poor working environment. Some suggestions were put forward to prevent the peeling of the chromium layer.

Tribological Properties of TiN Coating on Cotton Picker Spindle

“…Electroplated chromium coating has been used as a wear-resistant layer on the surface of spindles because of its low production cost, convenient operation, and high performance. However, it will cause serious environmental pollution and affect human health in the production process, and there are huge dense micro-cracks on the surface, which will have serious extension and propagation behaviors during friction and eventually cause the coating to crack or fall off [3,4]. In recent years, to improve spindle performance, studies are mainly conducted on spindle wear failure [5][6][7], simulation analysis [8,9], system design [10,11], and other aspects, but little research has been conducted on coating modification of spindle surface.…”