Maganin rashin ruwa, wanda kuma aka sani da maganin zafi na dehydrogenation, ko maganin zafi bayan walda.
Manufar maganin bayan zafi na yankin walda nan da nan bayan walda shine don rage taurin yankin walda, ko cire abubuwa masu cutarwa kamar hydrogen a yankin walda. Dangane da wannan, maganin bayan zafi da maganin zafi bayan walda suna da tasiri iri ɗaya.
Bayan walda, zafi yana rage yawan sanyaya na kabu na walda da haɗin haɗin gwiwa don haɓaka tserewar hydrogen da guje wa karuwar taurin.
(1) Bayan dumama don manufar inganta aikin haɗin gwiwar welded da rage taurinsa zai iya zama mai tasiri ne kawai lokacin da yankin walda ya kasance a yanayin zafi mai zafi bayan waldawa.
(2) Bayan dumama don hana ƙananan zafin jiki fasa shi ne yafi inganta isassun kau da hydrogen makamashi a yankin walda.
Kawar da hydrogen ya dogara da zafin jiki da kuma riƙe lokacin bayan dumama. Matsakaicin zafin jiki don babban dalilin kawar da hydrogen shine gabaɗaya digiri 200-300, kuma lokacin bayan zafi shine awa 0.5-1.
Don welds a cikin yanayi masu zuwa, maganin kawar da hydrogen bayan thermal ya kamata a gudanar da shi nan da nan bayan walda (maki 4):
(1) Kauri mafi girma fiye da 32mm, da ƙarfin ƙarfin ƙarfi na kayan abu σb> 540MPa;
(2) Low-alloy karfe kayan da kauri fiye da 38mm;
(3) Ƙaƙwalwar gindi tsakanin bututun da aka saka da jirgin ruwa;
(4) Ƙimar hanyar walda ta ƙayyade cewa ana buƙatar maganin kawar da hydrogen.
Yawan zafin jiki bayan zafi ana bayyana shi ta wannan dabara:
Tp = 455.5 [Ceq] p - 111.4
A cikin ma'auni, Tp - - zafin jiki bayan zafi ℃;
[Ceq] p——Madaidaicin dabarar Carbon.
[Ceq]p=C+0.2033Mn+0.0473Cr+0.1228Mo+0.0292Ni+0.0359Cu+0.0792Si－1.595P+1.692S+0.844V
Don rage abun ciki na hydrogen a cikin yankin walda yana ɗaya daga cikin mahimman tasirin maganin zafi bayan zafi. A cewar rahotanni, a 298K, tsarin yaduwar hydrogen daga ƙananan welds na carbon karfe shine watanni 1.5 zuwa 2.
Lokacin da aka ƙara yawan zafin jiki zuwa 320K, ana iya rage wannan tsari zuwa kwana 2 zuwa 3 da dare, kuma bayan dumama zuwa 470K, yana ɗaukar awa 10 zuwa 15.
Babban aikin jiyya bayan zafi da bushewa shine don hana samuwar fashewar sanyi a cikin ƙarfen weld ko a yankin da zafi ya shafa.
Lokacin da preheating na walda kafin walda bai isa ya hana samuwar sanyi ba, kamar a cikin walda na matsa lamba mai tsanani da kuma wuyar walda karafa, dole ne a yi amfani da tsarin bayan dumama don a dogara da hana samuwar. na tsagewar sanyi.
Lokacin aikawa: Maris 29-2023
