SU1703323A1 - Method of manufacturing permanent joint - Google Patents

Abstract

The invention relates to welding, in particular to welded joints of parts from steels of different structural classes, and can be used in the manufacture of products for important purposes, in particular the impellers of hydro turbines in various industries. The purpose of the invention is to improve the quality and operability of the welded joint of parts from dissimilar steels. The method consists in that the weld seam is made in two layers, the central part of the seam is made of a material with a doping level similar to that of its alloyed steel, and its thickness is equal to 100% of the seam thickness at the edge of the less alloyed steel part and evenly reduce to 40-60% of the weld thickness at the edge of a more alloyed steel part. The peripheral parts of the weld are made using welding materials with a doping level similar to that of more alloyed steel. The use of this method allows to eliminate the occurrence of fragile intermetallic interlayers, which allows improving the quality and operability of welded joints while reducing the consumption of high-alloyed welding consumables. 3 il. ate with

Description

The invention relates to the welding of parts from steels of different structural classes and can be used in the manufacture of products for important purposes, in particular the impellers of hydroturbines.

The aim of the invention is to improve the quality and operability of a welded joint of parts from dissimilar steels.

Figures 1 and 2 show butt joints with one-sided and two-sided edge cutting, respectively: in FIG. 3, a T-joint.

The method consists in welding two pieces of high-alloy steel 1 and low-alloy steel 2.

The central portion 3 of the weld is made using welding materials with a low doping level, and the peripheral portion 4 of the weld is made of a higher alloyed material. The thickness of the central part of the weld at the edge of the part from less alloyed steel is made equal to 100% of the total thickness of the weld and gradually reduced to 40-60% of the total thickness of the weld at the edge of the part from more alloyed steel.

When the thickness of the central part of the seam at the edge of a part from a more doped metal is less than 40% of the total cross section of the seam, not only does the performance of the welded structure decrease,

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The performance of the permanent welded joint unnecessarily increases the consumption of high-alloyed welding consumables, which leads to a decrease in the economic performance of the welding.

When the thickness of the central part of the seam at the edge of a part from more doped material is more than 60% of the total cross section of the seam, the performance of the welded structure decreases dramatically compared to the welded structure of the proposed method, since in this case the fatigue strength of the weld in general will be determined by the strength of the welded joint zone with brittle interlayers in the most dangerous section.

The expediency of increasing the thickness of the central part of the weld, performed at the edge of the part with less doping, to 100% is due to the fact that only in this case can the position of the fusion line of materials with different levels of doping perpendicular to the axis of the weld (product) be avoided and improve the performance and quality of the welded joint.

Example. The method is implemented in the manufacture of pilot welded joints of blanks from steel 06H12NZD with blanks from steel 20GSF. The thickness of the blanks and, therefore, the thickness of the seam is 100 mm,

The welding of the central section of the weld is performed by UONI 13/55 electrodes, using two welding of homogeneous welded joints 209 GSF and making it possible to obtain a weld metal similar to the alloying level of the 20GSF steel.

From the side of the billet of less alloyed steel, the filling of the cutting was carried out on the entire thickness of the seam. At the edge of the more alloyed steel part, the thickness of the central portion of the seam is made equal to 10,20,30-70 mm, which is respectively 10,20,30-70% of the seam thickness. The cutting is then welded onto a complete section with electrodes of the grade TsL-51, which make it possible to obtain a weld metal similar to steel 06Х12НЗД, and used for

welding homogeneous welded joints of parts made from this steel.

After welding, heat treatment was performed (tempering) of welded joints. From welded joints made samples for

studies of properties, the results of fatigue tests showed that the central part of the seam is most efficiently performed with the thickness of this area at the edge of a more alloyed steel part in

within 40-60%. At the same time, the fatigue strength of the welded joint can be obtained not only higher than when welding with the use of high-alloyed welding materials, but also higher than

when welding in the known way.

The proposed method allows improving the quality of welded joints, their performance and reducing the consumption of high-alloyed welding consumables.

Claims (1)

The invention The method of making a permanent connection of parts from dissimilar steels by welding, in which the weld is made of two irregular thickness sections of materials with different levels of doping, characterized in that, in order to improve the quality and operability of the welded joint, the central portion of the weld is made of material with a doping level corresponding to the alloying level of less alloyed steel, and its thickness at the edge of the part made of this steel is equal to 100% of the thickness seam and uniformly reduce this thickness to 40-60% of the seam thickness at the edge of the more alloyed steel, and the peripheral portions of the seam are made of a material with a doping level corresponding to the alloying level of the more alloyed steel. 13 2C h h Rig.Z