Editing Heat treating (section)

===Stress relieving===
Stress-relieving is a technique to remove or reduce the internal stresses created in metal. These stresses may be caused in a number of ways, ranging from cold working to non-uniform cooling. Stress-relieving is usually accomplished by heating a metal below the lower critical temperature and then cooling uniformly.<ref name="Dossett, 2006, 2-6" /> Stress relieving is commonly used on items like air tanks, boilers and other [[pressure vessel]]s, to remove a portion of the stresses created during the welding process.<ref>{{cite web|url=https://www.nationalboard.org/PrintPage.aspx?pageID=177|title=The National Board of Boiler and Pressure Vessel Inspectors|website=www.nationalboard.org|access-date=29 April 2018|url-status=live|archive-url=https://web.archive.org/web/20101220235320/https://nationalboard.org/PrintPage.aspx?pageID=177|archive-date=20 December 2010}}</ref>