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Cross-section of cold welding – before and after the weld. Cold welding or contact welding is a solid-state welding process in which joining takes place without fusion or heating at the interface of the two parts to be welded. Unlike in fusion welding, no liquid or molten phase is present in the joint. Cold welding was first recognized as a ...
The term weld is derived from the Middle English verb well (wæll; plural/present tense: wælle) or welling (wællen), meaning 'to heat' (to the maximum temperature possible); 'to bring to a boil'.
Cold metal transfer (CMT) is a welding method that is usually performed by a welding robot. The CMT machine detects a short circuit which sends a signal that retracts the welding filler material, giving the weld time to cool before each drop is placed. This leaves a smooth weld that is stronger than that of a hotter weld.
(a) Explain that Wikipedia's definition of cold welding in space is not the definition used by subject matter experts like the ESA, and (b) that the ESA has published an academic report explaining the difficulty in preventing what it considers to be cold welding in space. The ESA report is currently footnote 4:
Using a high energy mill to favor plastic deformation required for cold welding and reduce the process times; Using a mixture of elemental and master alloy powders (the latter to reduce the activity of the element, since it is known that the activity in an alloy or a compound could be orders of magnitude less than in a pure metal)
The welder must also keep the filler metal in the hot outer flame zone when not adding it to the puddle to protect filler metal from oxidation. Do not let the welding flame burn off the filler metal. The metal will not wet into the base metal and will look like a series of cold dots on the base metal. There is very little strength in a cold weld.
Vacuum cementing or vacuum welding is the natural process of solidifying small objects in a hard vacuum. [ clarification needed ] The most notable example is dust on the surface of the Moon . This effect was reported to be a problem with the first American and Soviet satellites, as small moving parts would seize together.
Aside from indicating that the Nixon administration might be willing to resume full-scale bombing of North Vietnam, the operation did not achieve very impressive results. [4]: 203 The VPAF campaign aimed precisely at countering the U.S. air interdiction campaign to which the President had keyed all his hopes for success, in making North Vietnam give up the fight and negotiate and in giving ...