Influence of residual stresses on resistance to brittle fracture in weldment zones
The relevance of the researchinthe field of welded joints strength and failure is associated with the necessity of ensuring high operational reliability and safety running hazardous production facilities. Internal stresses and their relaxation as an independent cause of destruction are widely recogn...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | Russian |
| Published: |
Tomsk Polytechnic University
2018-11-01
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| Series: | Известия Томского политехнического университета: Инжиниринг георесурсов |
| Subjects: | |
| Online Access: | http://izvestiya.tpu.ru/archive/article/view/2112 |
| Summary: | The relevance of the researchinthe field of welded joints strength and failure is associated with the necessity of ensuring high operational reliability and safety running hazardous production facilities. Internal stresses and their relaxation as an independent cause of destruction are widely recognized nowadays. The final form of the maximum permissible state is cracks appearance, however the signs of the appeared maximum permissible state of the node or structure are not clearly defined. The aim of the researchis to establish the signs of weld zone prefracture and fracture under redistribution conditions of internal stresses during thermal relaxation. The subject of the research iswelded superheater units made of dissimilar steels. Research methods: physical modeling of operating conditions by thermal cycling of samples in the MIMP-10UE electric furnace, X-ray dosimetry of the samples, internal structural stresses evaluation on DRON- type X-ray diffractometers, morphological analysis using the «Resource S7» metallographic analyzer, including an inverted Olympus GF41 microscope with the SIAMS Photolab software, cracks morphology with a PEN SCKOPE microanalyzer, microhardness analysis using a PMT-3 microhardness tester. Results. According to the hypothesis of crack formation correlation with internal stress relaxation, crack appearance and growth and stress relaxation are interrelated processes. As a result of thermal fluctuation relaxation, the same qualitative regularities (which lead to destruction) for a single-phase and two-phase system are found. Natural aging processes occurring in the sample with an initial crack in the absence of external loads and deformations are controlled only by internal stresses that activate all mechanisms of destruction, including phase decay. Under the conditions of internal stresses thermofluctuation relaxation, the temperature limit of the stress state region is set, which determines the reliable operating temperature. |
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| ISSN: | 2500-1019 2413-1830 |