Scrap steel types

[PS_Bond]

Would anyone have any idea what steel is used in gas struts? These were originally used on a campervan, I think. The central shaft is either plated or high alloy - hasn't rusted after a year or so outdoors, hardens to glass in water quench, sparks nicely but really does not like moving under the hammer.

Tried the usual junkyard steel lists, but they don't have anything I'd recognise as similar.