μδαπϊι 20 ωπδ πηωα ηγω αϊςωιιδ.
ψχ μφεψκ δωεεΰδ, θιτεμιν ϊψξιιν ωμ ηιρεν εδψτιδ ξϊεςγιν ξλξδ ξΰεϊ ωπιν μτπι δρτιψδ..
δζλψϊι χεγν ωηψεψ ξΰξφιν αδψςγδ, ξγεαψ αϊδμικ ωδϊηιμε μηχεψ αςψκ αωπϊ 1945, ςγιιο μΰ ξελη αΰετο ηγ ξωξςι ωςεαγ εςγιιο μΰ πηωα ξχεαμ αϊςωιιδ.
ΰηγ δτψξθψιν ωΰπι ηεωα ωπιϊο μδϊιιηρ ΰμιε λ"ξχεαμ" ζδ δξφΰεϊ ϊχιπδ ωξβγιψδ ΰικ μαφς ΰϊ δϊδμικ.
μβαι ξδ ωΰρσ ωΰμ, ξφΰϊι ςεγ δϊιιηρεϊ αειχιτγιδ. μΰ ιεγς ςγ λξδ ζδ ξαερρ ΰαμ μτι ξδ ωλϊεα ων δϊδμικ ϊετρ ςμ τμγεϊ ξρεβρβεϊ ωπωΰψ αδο μτηεϊ 10% ΰερθπιθ ωιεψι εφψικ μαφς ΰϊ δϊδμικ ξιιγ μΰηψ δηιρεν.

Cold and cryogenic treating

Main article:*Cryogenic treatment

Although quenching steel causes the austenite to transform into martensite, all of the austenite usually does not transform. Some austenite crystals will remain unchanged even after quenching below the martensite finish (Mf) temperature. Further transformation of the austenite into martensite can be induced by slowly cooling the metal to extremely low temperatures. Cold treating generally consists of cooling the steel to around -115˚F (-81˚C), but does not eliminate all of the austenite. Cryogenic treating usually consists of cooling to much lower temperatures, often in the range of -315˚F (-192˚C), to transform most of the austenite into martensite.

Cold and cryogenic treatments are typically done immediately after quenching, before any tempering, and will increase the hardness, wear resistance, and reduce the internal stresses in the metal but, because it is really an extension of the quenching process, it may increase the chances of cracking during the procedure. The process is often used for tools, bearings, or other items that require good wear resistance. However, it is usually only effective in high-carbon or high-alloy steels in which more than 10% austenite is retained after quenching.[28][29]



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