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Venkatesan, M. V.
- Study on Weldability of EN 10025-6 S550 QT Steel
Authors
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.
- Poka - Yoke in Welding
Authors
1 Technical Training Centre, Integral Coach Factory, Chennai, IN
2 Madras Institute of Technology, Anna University, Chennai, IN
Source
Indian Welding Journal, Vol 40, No 3 (2007), Pagination: 28-30Abstract
Integral Coach Factory is the Premier Coach (ICF) building Industry in Indian Railways. This factory has so far produced more than 30000 coaches in about 170 designs. It was the first among the Indian Railway production units to get ISO 9001 certification. Quality of the coach is being ensured from the raw material to end product. In ICF. fabrication of coaches are being carried out by welding process. Though welding is a reliable metal joining process, the soundness of the weldment largely depends on Men, Machine, Material and Method. The quality of the weldment is ensured by implementation of various quality tools. Even then it is quite difficult to achieve 100% defect free product in manufacturing. Even if 100% inspection is resorted to at every stage of manufacturing defects are inevitable since the inspection is being carried out by human and human errors are inadvertent and inevitable. Poka-Yoke is a tool which achieves 100% defect free product at low cost with the aid of low cost equipments. These low cost equipments aids the employee to manufacture defect free product. The aim of this study is to develop Poka-Yoke methods in a welding application. Few parameters which affect the quality of the weld are identified, and various methods are developed to control these parameters and eliminate defects. The parameters identified are shielding gas flow rate, pre and post heat temperature, welding sequence and electricity. These parameters are recorded in a standard format. Poka-Yoke Techniques were applied to control the above said parameters and ensure error free welding in ICF.
- Optimization of Application Techniques for Quenched and Tempered Steel-S550Q
Authors
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.