Welding Technology. Formulae Support. Vol. Heat Input for different processes:

Transcription

1 Welding Technology Formulae Suort Heat Inut for different rocesses: Residual stress due to uniform thermal exansion of a comonent: Note: Considering that, the comonent is in adiabatic condition, with uniform temerature distribution (T 0+), e.g. long time after the weld rocedure. Thermal Thermal HIL C Total E Where: Vol Volume of the comonent; L total Total length of the weld joint) Vol Thermal (if Thermal Yield ) 1

2 Dilution Rate (BM - Base Material; FM Filler Metal): DR BM BM FM Melt Melt Estimative of fusion area in a cross section of the weld bead, Aw: Emirical exressions for determination of relevant thermal cycle information: T c HI t Y T f 1 0 Note: exression valid for fusion welding of steels with 1 ass and full enetration - heat flow quasiarallel to late surface) Where: Y Distance from weld line into the HAZ, [mm] t Thickness of the workiece, [mm] T f Fusion temerature, [K] T 0 Pre-heat temerature, [K] T Peak/maximum temerature at distance Y from weld line, [K] HI Heat Inut, [J/mm] x c Secific heat caacity er un. of volume, [J/(mm 3.K)] 2

3 Determination of cooling rate, R: t R 2π k ρ C (T HI 2 2π k (T To ) R HI Where :, corresonds to relative HI c t R k Y º C J / mm º 0 J / mm mm C/s º J / mm. s. C 3 º C 2 T o 3 ) ; t C thickness. Adimension al ( T HI T o ) Equivalent Carbon content (IIW exression): C eq Mn Cr Mo V C 6 5 Ni Cu 15 Note: Ceq lower 0.35, no secial recautions are needed (e.g. no reheat temerature) Ceq higher 0.42, secial recautions are needed (e.g. reheat temerature is mandatory) 3

4 Procedure for the determination of Pre-Heat Temerature Determination of the Scale of Equivalent Carbon content: Carbon Equivalent Scale Weld Hydrogen Level Examles of corresonding rocesses and consumables Bead on late Butts Fillets Continuous surface Abutting surfaces Normal Misalignment Partial enetration, high constraint Full enetration, high constraint Normal structural fit Machined fit High constraint High Shielded Metal Arc Welding (SMAW) Submerged Arc Welding (SAW) Flux Cored Arc Welding (FCAW) A A A A A A A A A Medium Low Very Low (electrodes with non-dry basic flux) Shielded Metal Arc Welding (SMAW) Submerged Arc Welding (SAW) Flux Cored Arc Welding (FCAW) (electrodes dry to 250ºC and above) Shielded Metal Arc Welding (SMAW) Submerged Arc Welding (SAW) Flux Cored Arc Welding (FCAW) (electrodes dry to 350ºC and above) GMAW with solid dirty wires Shielded Metal Arc Welding (SMAW) Submerged Arc Welding (SAW) Flux Cored Arc Welding (FCAW) (electrodes dry to 450ºC and above) TIG and GMAW with solid clean wires C B B B A A B C A D C C C A B C D B D D D D A C D D C Where: Combined thickness, t c t i n i1 t i corresonds to the thickness of the comonent i, adjacent to the weld bead n number of comonents adjacent to weld bead 4

5 Alternative simlified rocedure for the determination of Pre-Heat Temerature based on British Standard: BS 5135: 5

6 Hot Cracking Suscetibility index: Limit values of Hot Cracking Suscetibility (H.C.S.), are: H.C.S 4 (or 3.6, for low alloy steels) Nakamura and Ito: 6

7 Diagrama de Schaeffler (1948): Prevision of the Microstructure in Weld Zone of Stainless Steels Identification: Name: Number: 7

8 WRC 92 (1992): Prevision of the Microstructure in Weld Zone of Stainless Steels Identification: Name: Number: 8