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Kumar, R.
- Study on Weldability of EN 10025-6 S550 QT Steel
Abstract Views :297 |
PDF Views:5
Authors
Affiliations
1 Engineering Workshop, Larsen & Toubro Limited, IN
2 Larsen & Toubro Limited, IN
1 Engineering Workshop, Larsen & Toubro Limited, IN
2 Larsen & Toubro Limited, IN
Source
Indian Welding Journal, Vol 51, No 4 (2018), Pagination: 86-92Abstract
Cracks developed in the 90 mm thick EN 10025-6 S550 QT steel plates assembled to form a box unit. After assembly the surface cracks generated longitudinally along the elongated grains while preheating or performing ischolar_main run. Root cause analysis was conducted to investigate the reason for the failure and also how to specify the “conditions of materials on delivery” during procurement is generated. Various tests such as visual test, chemical composition, inclusion rating, microstructure, dye penetrant test and hardness tests were conducted. The investigation revealed that the failure cracks could be due to temper embrittlement due to the segregations of impurities such as tin, arsenic, phosphorus and antimony, etc. in the grain boundaries and resulted in ductile to brittle transformation when exposed in the temperature. It is observed that, depends on the concentration of Ti and N in steel, coarse and cuboidal TiN particles of several micrometers in size act as potential sites for cleavage crack initiation. Furthermore, during the steel making process if sulfur is not properly controlled, then large MnS inclusions can also form during solidification. Soft MnS inclusions elongate during the subsequent hot rolling process, which deteriorate ductility and impact toughness. Hence, it is essential to specify the J factor value and inclusion rate during the procurement of steel.Keywords
Inclusion Rate, Welding, Quenched Hardened Steel, Tempering, J-factor.References
- Anmark N, Karasev A and Jonsson PG (2015); The effect of different non-metallic inclusions on the machinability of steels, Materials 8, pp. 751-783. doi:10.3390/ma 8020751.
- Grosse-Wordemann J and Dittrich S (1983); Prevention of temper embrittlement in 21/4 Cr-1 Mo weld metal by metallurgical action, Welding Journal, 10(5) pp. 123s 128s.
- American Society for Metals, Volume 4.
- Optimization of Application Techniques for Quenched and Tempered Steel-S550Q
Abstract Views :375 |
PDF Views:5
Authors
Affiliations
1 Engineering Workshop, Larsen & Toubro Limited, Kanchipuram, IN
2 DGM-Larsen & Toubro Limited, Kanchipuram, IN
3 DGM-L&T Construction, Larsen & Toubro Limited, Kanchipuram, IN
1 Engineering Workshop, Larsen & Toubro Limited, Kanchipuram, IN
2 DGM-Larsen & Toubro Limited, Kanchipuram, IN
3 DGM-L&T Construction, Larsen & Toubro Limited, Kanchipuram, IN
Source
Indian Welding Journal, Vol 52, No 2 (2019), Pagination: 35-43Abstract
EN10025-6 S550Q is high strength steel classified under quenched and tempered (Q&T) manufacturing technique. S550Q is specially designed and used by the authors for welded steel structures for the purpose of heavy lifting and lowering. The entire processing techniques like cutting, edge preparation, welding, and bending are of major importance to the consistency of fabricated structure. This study comprises of introduction to HSS-S550Q and addresses various important variables by practically. The following main factors are taken to consideration heat input during cutting, edge preparation, and welding, cooling cycle, Hydrogen induced cracking (HIC). Stress Relieving (SR) is mandatory after weld fabrication. The first was to establish a need for SR to achieve desirable weldment properties. SR has been reported to have Complementary benefits such as tempering of WM and HAZ regions, and allowing the effusion/diffusion of hydrogen away from the weld region. Bend testing of cross-weld samples was used to qualify the ductility of the weldment before and after SR. In addition, impact, tensile and hardness properties, microstructures were quantified before and after SR.Keywords
S550Q, EN 1011-2, Thermal Cutting, Welding, Stress Relieving, ASME SEC-IX (2015), EN ISO15614.References
- Basu B and Raman R (2002); Microstructural variations in a high-strength structural steel weld under isoheat input conditions, Welding Journal, 81, pp. 239- 248.
- Porter D (2006); Development in hot-rolled high-strength steel, Nordic Welding Conference 06 on New Trends in Welding Technology, Tampere, Finland.
- Pisarski HG and Dolby RE (2003); The significance of softened HAZs in high strength structural steels, Welding in the World, 47(5/6), pp. 32-40.
- Umekuni A and Masubuchi K (1997); Usefulness of under matched welds for high-strength steels, Welding Journal, 76(7), pp. 256-263.
- Wang J, Li Y and Liu P (2003); Effect of weld heat input on toughness and structure of HAZ of a new super-HSS, Material Science, 26(3), pp. 301-305.
- Magudeeswaran G, Balasubramanian V, Madhusudhan Reddy G and Balasubramanian TS (2008); Effect of welding processes and consumables on tensile and impact properties of high strength quenched and tempered steel joints, Journal of Iron and Steel Research International, 15, pp. 87-94.
- Shi Y and Han Z (2008); Effect of weld thermal cycle on microstructure and fracture toughness of simulated heat-affected zone for a 800 MPa grade HSS, Journal of Materials Processing Technology, 207, pp. 30-39.