SU1708565A1 - Method of thermal and mechanical treatment of welded joints - Google Patents

Description

The invention relates to methods for the welding of welded joints, in particular, to thermomechanical processing, and can be used in various industries, for example, in metallurgical enterprises in technological lines for the production of rolled steel from alloyed steels prone to embrittlement of the seam and heat affected zone. neither .

Thermomechanical treatment methods are known that are used to improve the performance properties of welded joints by plastic deforming the weld metal and heat-affected heat-affected zone.

The main disadvantage of the prototype is the simultaneous deformation in the hot state of the seam and the heat-affected zone adjacent to it. Experiments show that for thermally embrittleable and weakening materials, the deformation mechanism inherent in the prototype is ineffective, because a welded joint is characterized by the presence of a wide range of transitional structures. At the same time, the general mode of heating and reduction does not provide the individual approach required for embrittleable areas and the corresponding nature of the movement of the metal in the deformities. This disadvantage is illustrated by the example of machining welded joints from

transformer steel with a high content of silicon (3.5 ... 4.8%). Welded joints of this steel in the state after welding are characterized by considerable coarseness in the heat-affected zone and the presence of precipitates of silicide and carbide phases stable at elevated temperatures along the grain boundary. In such a combination, favorable conditions are created for the occurrence of microdefects that reduce several times (10) the ductility and toughness compared with the base metal.

As experiments show, in areas with a brittle structure, in order to heal microdefects and improve the plastic properties of the metal, the degree of deformation is increased compared with other zones. At the same time, places with a local decrease in thickness are often unacceptable in welded joints.

In this connection it is necessary to create conditions for the return movement of the metal to the thinned areas. The prototype deforming scheme adopted in the prototype does not provide such a process. In addition, during the thermomechanical treatment of welded joints, local, mainly in / out, heating of the seam and the adjacent areas is carried out. In this case, the temperature field in the area to be treated is characterized by the presence of a zone in which the temperature has a maximum value with a rather sharp decrease thereof outside the cross section of the inducing wire.

Welded joints in most cases have reinforced seams. In the process of reduction, the metal characteristic of the prototype will be reinforced during local heating. partially move to areas of low temperature, thus forming sails (sunsets) ..

Compression of the metal in the local heating zone according to the well-known scheme (with the rolling of the weld in the E-transverse direction) is carried out with one-sided movement of the welded joint: - With respect to the crimping tool (rolls). At the same time, sunsets are formed and conditions are created that favor the development of microdefects in the zone where the rolling is carried out in the direction of the temperature decrease,

In order to eliminate these drawbacks in the proposed method of thermal processing, in which local heating and plastic deformation of the seam and heat affected zone are performed, first

plastic deformation of areas adjacent to the weld by application of;;) necessary for deforming the force on both sides of the welded joint,

and then - plastic deformation of the seam. Due to this, preliminary healing of microdefects is carried out. Due to the continuous or discrete movement of the metal from the deformed foci in the direction of the positive temperature gradient, a wave is formed (local thinning and thickening), which is smoothed when re-compressed, eliminating local

thinning. The discrete movement of the metal to the zone where the top of the wave is formed can be carried out with the displacement of the places of heating and reduction.

The proposed method is illustrated.

drawing.

Claims (7)

1. Method of thermomechanical treatment of welded joints, in which heat and plastic deformation of the welded joint are carried out in a hot state, characterized in that, in order to improve the performance characteristics of the welded joints from materials that become brittle after welding, plastic deformation of the areas adjacent to the weld is first carried out by applying the necessary deformation of forces on both sides of the welded joint, and then - plastic deformation of the seam. 2. The method according to A.1, about tl and h a y i and with the fact that the deformation adjacent to the weld of the sections is carried out discretely with a successive-progressive displacement of places where a force of deformation is applied. 3. Method according to Claims 1, 2, 1 and 2, so that heating and plastic deformation on each side of the seam is carried out alternately. 4. A method according to claims 1 to 3, characterized in that the heating and plastic deformation of the sections adjacent to the weld seam are performed simultaneously along the entire surface. 5. The method according to PP, 1-4, about tl and h a y i and i with the fact that plastic deformation carried out by successive crimping in the direction of the longitudinal axis of the seam. 6. A method according to Claims 1-5, characterized in that the plastic deformation is carried out with a discrete increase in strain strain. 7. The method according to paragraphs. 1-6, that is, with the fact that in the process of plastic deformation of the treated area The weld is fixed on both sides of the weld.