The method for determining the propensity of rolled metal to layered destruction


(57) Abstract:

Use: in testing equipment, tensile testing. Essence: in the sample is cut in the thickness direction of the car, creating tension and reduce cyclic load method of heating-cooling insert installed sequentially aligned sample and rigidly bonded with him. The strength of the material of the insert exceeds the strength of the material sample. 1 C. p. F.-ly, 1 Il.

The invention relates to the study of physical-mechanical properties of rolled metals, namely the anisotropy of plasticity and viscosity, which causes formation during welding of layered cracks.

Known mechanical methods of determining the propensity to hire layered destruction with the application of load in the thickness direction of the car. They include the application of tensile force to the core samples cut perpendicular to the plane of the Bicycle.

You know the drop test bending or methods of fracture mechanics specimens with a notch or induced crack located in the plane of the Bicycle, the test for static bending of flat samples cut in the thickness direction crosswise to the direction of p is the preliminary plastic deformation in the thickness direction of the car.

The disadvantage of the methods of mechanical tests is that they do not reflect the possible effects on the propensity to layered destruction effects of thermal and deformation cycles welding, and other related welding factors. Under the influence of heat and power effects of welding individually change the microstructure and mechanical properties of the metal, it is saturated with hydrogen, it flow deformation and thermal ageing. All this cannot but affect the reliability of determination of the inclination of the base metal to the formation of layered cracks.

Also known testing methods, in which the layered destruction occurs in the samples under the influence of its own stresses welding is initiated or tensile stresses from external forces applied to the sample during the welding process or after its completion.

In these methods, the criterion penchant for layered destruction rental is the presence or absence of cracks, and the value of the critical voltage, causing the formation of cracks.

However, these methods are characterized by great intensity, complexity and cost and give qualitative rather than quantitative assessment of p the market and stresses in the cross section of the connection, high speed changes in these characteristics over time make it difficult to separate the study of the role of individual factors in the formation of cracks and their conditions of occurrence.

The closest technical solution of the invention is a method for determining the propensity of rolled metal to layered destruction during welding by testing a sample of the metal to the efforts of the compression-tension in terms of simulated thermal deformation cycles. Quality steel are the maximum stress and strain endured by the sample at the destruction.

A significant drawback is the unreliability of the test results due to inconsistencies simple stretching deformation of the welding cycle. When welding each element of the metal compound sequentially undergoes compression due to local heating and stretching during cooling. When the multilayer welding (which mainly explains the appearance of layered cracks) deformation cycles periodically repeated.

The purpose of the invention is to increase the reliability of test results.

This is achieved by the fact that the efforts applied to the sample using thermal expansion coaxially located with the sample rod will westerhout heating and cooling in thermal cycle of welding, and the test specimen cut out from a rolled in the direction of its thickness and provide test specified constant or variable heat treatment of the sample, and on the resistance of the layered destruction judged by the number of cycles of compression-tension and the total plastic deformation, leading to destruction of the sample.

In addition, the core insert perform with strength greater than the strength of the test sample.

The drawing shows a circuit implementing the method.

The method is implemented in the following sequence.

The test sample 1 is cut out from a rolled in the direction of its thickness and feature between the rigid grip 2 and the connecting yoke 3, which is on the opposite side coaxially with the sample will montirat hard core box 4, which has greater strength properties than the test sample 1. When this box 4 teploizolirovat from sample to create a test independent of temperature regimes.

The free end of the rod inserts are also rigidly fixed to the grip 5. After that, the paste is subjected to heating and cooling in thermal cycle of welding, and the person concerned about the Denia rod insert 4 on the test sample is passed through the ferrule 3 cyclic mechanical load. Warm the insert 4 and its thermal expansion initially cause compression of the sample. With increasing heating temperature and a sharp decline in the material of the insert is plastic deformation of compression, which causes a slight increase in the diameter of the insert and to a reduction of finite length. Upon further cooling, the paste due to the "defect length in the system to insert the sample occurs tensile stress exceeding the yield strength of the sample and causing his plastic elongation.

Repeated heating and cooling of the insert 4 excite the sample 1 repeated cycles of compression-tension, which is accompanied by accumulation (summation) of the deformation characteristic of the multi-layer welding.

The criterion of quality material in this test is the number of cycles to failure of the sample and the maximum total plastic deformation.

Before testing the sample by using the heat treatment can be created with different microstructure corresponding to one of the characteristic zones of the welded connection (high holidays, complete or incomplete recrystallization, overheating).

The temperature of the sample 1 when the test can p the RCTs.

The heating rate and the cooling rod insert 4 can be varied within wide limits.

This allows using the proposed method separate study of the effect on the propensity to layered destruction hire various metallurgical and technological factors with a high degree of accuracy. (56) Jombardini I Einflub des Terrasseubruches Sehweiftechnik, 1978, N 9, p. 168-174.

1. The method for determining the propensity of rolled metal to layered destruction, namely, that the metal sample is exposed to cyclic loads efforts compression, and penchant for layered destruction judged by the number of cycles to failure, characterized in that, in order to bring credibility by bringing to the conditions of thermal deformation cycles welding, coaxially with the sample and consistently with him install the insert, opposite ends of which are rigidly interconnected and available rigidly fixed in the clamps, the effects of cyclic load perform cyclic heating - cooling insert and the sample cut out from a rolled in the direction of its thickness.

2. The method according to p. 1, characterized in that the insert is made of a material whose strength exceeds strongly the


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