An upper member of a steel piston has a chemical composition which consists of, in mass %, C: 0.15 to 0.30%, Si: 0.02 to 1.00%, Mn: 0.20 to 0.80%, P: 0.020% or less, S: 0.028% or less, Cr: 0.80 to 1.50%, Mo: 0.08 to 0.40%, V: 0.10 to 0.40%, Al: 0.005 to 0.060%, N: 0.0150% or less, O: 0.0030% or less, and the balance: Fe and impurities, and satisfies Formula (1) and Formula (2), in which, at a cross section parallel to the axial direction of the upper member, the number of Mn sulfides is 100.0 per mm.sup.2 or less, the number of coarse Mn sulfides having an equivalent circular diameter of 3.0 μm or more is within a range of 1.0 to 10.0 per mm.sup.2, and the number of oxides is 15.0 per mm.sup.2 or less.
0.42≤Mo+3V≤1.50  (1)
V/Mo≥0.50  (2)

Coatings that can be used on limited line of sight substrates are described. In some embodiments, the coating may be a metal alloy coating applied to an inner surface of an article such as a rod, tube or pipe. The inner surface can be present within a cavity of an article.

Shock absorbers that include a piston member configured to contact a functional fluid during movement of the piston member are described. The piston member can include a coating on a surface of the piston member. The coating can include a metal or metal alloy such as, for example, molybdenum or tungsten in combination with one or more other materials.

Rods and pipes that include a coated surface are described. The rod or pipe can include an alloy layer on a surface. The alloy layer can include molybdenum or tungsten and at least one element or at least one compound comprising one or more of nickel, cobalt, chromium, tin, phosphorous, iron, magnesium or boron.

Metal work rolls that contact a functional fluid during movement of a rotatable body are described. The rotatable body can include a coated surface with a surface coating. The surface coating can include a metal or metal alloy such as, for example, a molybdenum alloy or a nickel alloy or a tungsten alloy. Systems and processes using the coated work rolls are also described.

Rotational devices that include a substrate with a coated surface are described. The coated surface can include an alloy layer with molybdenum or tungsten and at least one element selected from the group consisting of nickel, cobalt, chromium, tin, phosphorous, iron, magnesium and boron. Systems including the rotational devices are also described.

Pneumatic articles that include a moveable component with a coated surface are described. The coated surface can include a surface coating including an alloy layer that includes molybdenum or tungsten in combination with one or more other materials. Pneumatic cylinders and pneumatic devices are also described.

Pneumatic articles that include a moveable component with a coated surface are described. The coated surface can include a surface coating including an alloy layer that includes molybdenum or tungsten in combination with one or more other materials. Pneumatic cylinders and pneumatic devices are also described.

Hydraulic devices that include a moveable component configured to contact a functional fluid during movement of the hydraulic device are described. The hydraulic device can include a coating on a surface. The coating can include a metal or metal alloy such as, for example, a molybdenum or tungsten in combination with one or more other materials.

Reciprocating devices that include a moveable component configured to contact a functional fluid during movement of the moveable component are described. The moveable component can include a coating on a surface of the moveable component that contacts the functional fluid. The coating can include a metal or metal alloy such as, for example, a molybdenum in combination with one or more other materials. Pneumatic and hydraulic devices and devices are also described.