Ganpat Metal Industries is renowned Distributor and Manufacturer of Carbon Steel Butt Weld Fittings, which cannot be hardened by thermal treatment, but does work harden. Solution treatment (annealing) – heat is up to 1020 Degree C – 1100 Degree C and cool rapidly. https://www.ganpatmetal.com/carbon-steel-buttweld-pipe-fittings-manufratures-expoters-suppliers-stockists.html