PSI - Issue 20

G.S Ammosov et al. / Procedia Structural Integrity 20 (2019) 306–309 G.S Ammosov and M.P. Lebedev / Structural Integrity Procedia 00 (2019) 000–000

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Thus, the volume of the deposited weld metal can be determined with a given thickness and grade of the welded sheets of the wall or the bottom of the tank. 3. Research materials Using the expression (1) for determining the weld deposit volume and knowing the cooling rate equal to � 6/5 , the Vickers hardness (HV) is determined for the steels of 09Mn2Si, St3, and 17Mn1Si grades according to CCT diagrams. Afterwards, it is changed into the Brinell hardness (HB) according to the conversion tables did by Kalner V.D., Shor F.I. (1997) To calculate the yield stress σ 0.2 and the tensile strength σ В , the formulas proposed by Markovets M.P. (1979) were used to obtain the following graphs (see Fig. 1). The volume of the deposited weld metal determined by the cross-sectional area � � according to the nominal structural-technological weld size as per GOST 5264-80, calculated according to the standard dependence for butt welds 6 mm and 8 mm thick, has the following values: ~ 26 and ~ 28 mm 2 . Figure 1 demonstrates the graphs obtained by numerical solution of expression (1). It can be seen that with decreasing the volume of the deposited weld metal, the strength characteristics increase. It should be noted that the reduction in the volume of the deposited weld metal consequently causes an increase in the cooling rate of the HAZ metal and the superheated area is reduced as well. As it is established by Bakshi O.A., Shatov A.A. (1966) in the process of cooling of welded joint, the involvement into the plastic deformation of a section with a hard interlayer in the HAZ will depend on the width, which is in turn influenced by the heat input, i.e. the smaller the width of the section with a hard interlayer is, the less the plastic deformation in the section with a hard interlayer will be. Consequently, the residual stress in the HAZ will decrease.

Fig. 1. Dependences of strength characteristics on weld deposit area a) 09Mn2Si steel, b) St3 steel c) 17Mn1Si steel.