AWS D14.8M pdf free download
AWS D14.8M pdf free download.Standard Methods for the Avoid ance of Cold Cracks.
If of the elements in this formula only carbon and manganese are stated on the mill sheet for carbon and carbon manganese steels, then 0.03 % should be added to the calculated value to allow for residual elements and impurities. Where steels of different carbon equivalents or grades are to be joined, the higher carbon equivalent value should be used. This carbon equivalent formula may not be suitable for boron containing steels. 2.3 Plate thickness and joint geometry The influence of plate thickness and joint geometry is determined by calculating the combined thickness. This should be determined as the sum of the parent metal thickness averaged over a distance of 75 mm from the weld center line (see Figure 1). Combined thickness is used to assess the heat sink of a joint for the purpose of determining the cooling If the thickness increases greatly beyond 75 mm from the weld center line, it may be necessary to use a higher combined thickness value. Steels with thicknesses, t, in the range 6 mm S t≥100 mm were used in the tests to develop the scheme. 2.4 Hydrogen level and welding process 2.4.1 Hydrogen scales The hydrogen scales to be used for any arc welding process depend principally on the weld diffusible hydrogen content (according to IsO 3690) and should be as given in Table 2.
Shielded metal arc welding with basic covered electrodes can be used with the scale B to D depending on the electrode manufacturer’s/supplier’s classification of the consumable. Shielded metal arc welding with rutile or cellulosic electrodes should be used with scale A. Flux cored or metal cored consumables can be used with scales B to D depending on the manufacturer’s/supplier’s classification of the wire electrodes. Submerged arc welding with one wire electrode (121) and flux consumable combinations can have hydrogen levels appropriate to scales B to D, although most typically these will be scale C but therefore need assessing for each named product combination and condition. Submerged arc fluxes can be classified by the manufacture/supplier but this does not necessarily confirm that a practical flux wire combination also meets the same classification. Solid wire electrodes for gas metal arc welding (131, 135) and for gas tungsten arc welding (141) may be used with scale D unless specifically assessed and shown to meet scale E. Scale E may also be found to be appropriate for some flux cored wires (136, 137) and some shielded metal arc welding electrodes, but only after specific assessment. In achieving these low levels of hydrogen consideration should be given to the contribution of hydrogen from the shielding gas composition and atmospheric humidity. For plasma arc welding (15), specific assessment should be made. NOTE The numbers in brackets are process numbers according to ISO 4063. 2.5 Heat input Heat input values (in kJ/mm) for use with Figure 2 a) to m) should be calculated in accordance with EN 1011-1/ ISO/TR 17671-1 and EN 1011-2/ISO/TR 17671-2. For shielded metal arc welding, heat input values are expressed in Tables 3 to 6 in terms of electrode size and weld run lengths.AWS D14.8M pdf download.
