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toughening
toughening n. 
/ˈtʌf(ə)nɪŋ/
/ˈtʌf(ə)nɪŋ/ΘΚΠ
the world > matter > constitution of matter > strength > [noun] > toughness > making tough
toughening1868
1868 F. H. Joynson Metals in Constr. 45 The toughening of cast-iron.
1869 E. J. Reed Shipbuilding xxi. 317 The toughening effect produced on a mass of Steel when it is heated, and plunged into a bath of oil.
1881 Trans. Amer. Inst. Mining Engineers 1880–1 9 187 Toughening, refining, as of copper or gold.
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