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CONARC ® steel making process is a combination of convertor steel making and electric arc steelmaking to get the benefit of both the process and make it flexible in terms of using raw material feed mix. Raw material feed mix in this furnace on an average is 60% hot metal (HM), 38% cold direct reduced iron (CDRI) and 2% steel scrap. In this furnace operation there are two phases, namely, the oxygen blowing phase and arcing phase followed by tapping of steel into the ladle. During the oxygen blowing phase, the HM carbon content is reduced from 4.5% to 0.3%–0.5%, and further reduced to 0.025–0.03% in the arcing phase depending upon the grade of steel produced. During the arcing stage, CoJet™ lances are used for the oxidation of the bath and reduction of the carbon content to the desired values. The end point %C parameter is very important in CONARC ® steel making as it determines the productivity and quality of the steel produced. Based on the analysis, mathematical and machine learning approach was adopted to predict the end point %C during the arcing stage of the furnace. The algorithms which are used and compared are the tree-based models and support vector machines. After comparing the results, the tree based model seems best fit after further optimization to get an accuracy of 83%. The model was validated with plant trials and the accuracy was found to be within ±0.013 %C.

Ti-stabilized interstitial free steel subjected to eight passes, route B C room temperature equal channel angular pressing (ECAP) additionally was cold rolled (CR) up to 95 pct thickness reduction. Electron back-scattering diffraction and transmission electron microscopy characterized microstructural refinement and microtexture evolution, whereas the mechanical properties were assessed by uniaxial tensile tests. After 95 pct CR, the average high-angle grain boundary spacing reduces to 0.14  μ m, whereas the high-angle boundary fraction increases to ~81 pct. The ECAP negative simple shear texture components rotate by ~15 deg around the transverse direction toward the rolling direction for up to 50 pct CR, with typical rolling textures observed at 95 pct CR. The decrease in boundary spacing produces a ~500 MPa gain in 0.2 pct proof stress, a ~600 MPa increase in ultimate tensile strength (UTS), and a ~4 pct loss in total elongation after 95 pct CR. Similar rates of decrease in work hardening correspond to comparable rates of cross and/or multiple slip events irrespective of the processing regime and substructural refinement. The fracture mode of the tensile samples changes from ductile to brittle type between ECAP and 95 pct CR and is attributed to the reduced work hardening capacity of the latter. The modified Hall–Petch equation shows that the convergence of high-angle boundary spacing values with their low-angle counterparts results in an increased contribution via boundary strengthening to the 0.2 pct proof stress and UTS.

Detailed metallographic analysis was carried out to ascertain cause of failure in a pinion shaft of a tail breaker unit installed in a TMT rebar mill. Visual examination showed the failure to occur in a plane perpendicular to its length at a point of a sudden change in cross-sectional area in the shaft. Fractography-revealed fatigue as the primary mode of failure and examination under optical and scanning electron microscopes (SEM) showed the failure to be facilitated by the non-uniform thickness and inhomogeneous microstructure of the repair-welded surface (outer) layer of the shaft. Furthermore, the presence of undesirable MnS and Ca–Si inclusions detrimental to the service life of the shaft under dynamic loading conditions was detected at the interface of the reworked outer and the inner surface of the shaft by means of SEM–EDS. The following two primary inferences drawn from observations made in the present study are suggested as the root cause of failure of the pinion shaft: (i) improper repair welding of the surface, i.e. weld surfacing and (ii) inferior quality of the shaft material as evidenced by presence of undesirable inclusions.

Co-injection of natural gas (NG) with pulverized coal (PC) is carried out in blast furnace to increase the coal burnout; however, it has major challenges such as excess heat load on tuyere, lance overheating and competition between coal volatile matter and NG for available oxygen. A 3D computational fluid dynamics model of the blast pipe-tuyere-raceway region is developed to study the effects of: (1) NG and PC injection (PCI) through the co-axial lance and the subsequent oxygen enrichment on coal burnout and (2) relative positioning of NG and PCI lances in a double-lance design on coal burnout and localized temperature rise on PC lance. In the co-axial lance case, the use of NG as a cooling gas instead of oxygen decreases burnout from 54 to 43%. In double-lance design, positioning NG lance prior to PC lance results in relatively higher % burnout than the reverse configuration and does not lead to the overheating on PC lance.

Introduction: There is a lack of Indian data on short stature treatment using recombinant human growth hormone (rhGH). We explored the effects of such treatment in eastern Indian patients, with emphasis on biochemical parameters and bone biomarkers in addition to basic anthropometry. Methods: Our descriptive study covered 50 short stature patients of varied aetiology attending endocrine outpatient department (OPD) of a tertiary care teaching hospital. Patients were followed up for 1 year after the index visit, and prospective data were reconciled with past medical records. A dose of rhGH used was 0.18-0.375 mg/kg as standard, starting dose mostly being 0.2 mg/kg. Dosing was adjusted if the physician judged the clinical outcome to be less favourable than expected. Anthropometric parameters (height, weight, body mass index (BMI) and skeletal age) were recorded clinically, and various biochemical parameters and bone biomarkers were estimated from blood. Results: Among 50 subjects, 60% had idiopathic growth hormone (GH) deficiency and 26% had Turner's syndrome. The median age at treatment start was 10 years, and the median treatment duration was 25.5 months. The height increased more in the first year of therapy. In the last 6 months, the height velocity was approximately 0.5 cm/month. Although the weight increased significantly, the increment slowed down in the last 6 months. Both remained less than age- and gender-matched references throughout. The skeletal age was on average 2 years behind chronological age (CA)-being 8.7, 9.6 and 11.3 years, respectively, at therapy start, after one year and at study end. Fasting blood glucose (FBG), total cholesterol and calcium level changes were not statistically significant. Serum cortisol and phosphate showed a modest but statistically significant rise, while thyroid-stimulating hormone (TSH) level declined. Insulin-like growth factor 1 (IGF-1) increase was relatively pronounced. Among bone biomarkers, a decrease in CTx and an increase in vitamin D were significant. Dual-energy X-ray absorptiometry (DEXA) data indicated that bone mineral density was less than that of age-matched controls despite treatment. The therapy was well tolerated. Conclusions: rhGH treatment leads to significant improvement in anthropometry in Indian children comparable with Western data. Bone biomarker changes indicate decreased bone resorption and increased bone formation although bone mineral density still lags behind age-matched controls.

A Nb-Ti containing high-strength low alloy (HSLA) steel (S700MC grade, YS = 700 MPa) was subjected to hot rolling and coiling simulation experiments in a dilatometer to investigate the effect of cooling conditions, i.e., cooling rate (CR) and coiling temperature (CT) on the principal strengthening mechanisms, viz. precipitation and grain size strengthening. The three cooling rates and two coiling temperatures employed in the present study were 10, 20 and 30 °C/s and 590 and 650 °C, respectively. A major finding of the present study was the increase in hardness and consequently the strength with an increase in CT at all cooling rates. This was attributed to the increase in precipitation contribution to strength at the higher CT. Furthermore, the increase in precipitation contribution was accompanied by only an insignificant reduction in grain size strengthening, thereby leading to a net increase in strength with increase in CT. However, the strength enhancement due to increase in CT diminished with an increase in CR. Hence, based on the findings of the present study, an optimized coiling temperature is suggested for S700MC grade steel for a range of thicknesses to maximize the precipitation contribution to strength without significantly altering the contributions provided by evolved phases and grain size, respectively.

Introduction: There is a lack of Indian data on short stature treatment using recombinant human growth hormone (rhGH). We explored the effects of such treatment in eastern Indian patients, with emphasis on biochemical parameters and bone biomarkers in addition to basic anthropometry. Methods: Our descriptive study covered 50 short stature patients of varied aetiology attending endocrine outpatient department (OPD) of a tertiary care teaching hospital. Patients were followed up for 1 year after the index visit, and prospective data were reconciled with past medical records. A dose of rhGH used was 0.18-0.375 mg/kg as standard, starting dose mostly being 0.2 mg/kg. Dosing was adjusted if the physician judged the clinical outcome to be less favourable than expected. Anthropometric parameters (height, weight, body mass index (BMI) and skeletal age) were recorded clinically, and various biochemical parameters and bone biomarkers were estimated from blood. Results: Among 50 subjects, 60% had idiopathic growth hormone (GH) deficiency and 26% had Turner's syndrome. The median age at treatment start was 10 years, and the median treatment duration was 25.5 months. The height increased more in the first year of therapy. In the last 6 months, the height velocity was approximately 0.5 cm/month. Although the weight increased significantly, the increment slowed down in the last 6 months. Both remained less than age- and gender-matched references throughout. The skeletal age was on average 2 years behind chronological age (CA)-being 8.7, 9.6 and 11.3 years, respectively, at therapy start, after one year and at study end. Fasting blood glucose (FBG), total cholesterol and calcium level changes were not statistically significant. Serum cortisol and phosphate showed a modest but statistically significant rise, while thyroid-stimulating hormone (TSH) level declined. Insulin-like growth factor 1 (IGF-1) increase was relatively pronounced. Among bone biomarkers, a decrease in CTx and an increase in vitamin D were significant. Dual-energy X-ray absorptiometry (DEXA) data indicated that bone mineral density was less than that of age-matched controls despite treatment. The therapy was well tolerated. Conclusions: rhGH treatment leads to significant improvement in anthropometry in Indian children comparable with Western data. Bone biomarker changes indicate decreased bone resorption and increased bone formation although bone mineral density still lags behind age-matched controls.

The present work is a result of the detailed metallographic investigation carried out to ascertain the cause and mechanism of premature failure observed in a particular batch of water-cooled copper tuyeres of a recently commissioned blast furnace (BF) at JSW Steel Ltd., Dolvi Works. In the present case, the tuyere failures were observed to occur in the form of cracks selectively at specific location—the inner circumferential weld joining the inner wall to the tuyere nose. Improper welding/lack of fusion was identified as the underlying cause of this failure with a minor design flaw acting as the point of initiation of the same. Based on the observations, the following mechanism of failure was proposed: the design flaw (i.e., the notch between inner wall and tuyere nose) and the narrow clearance in between the base metals in the no fusion zone provides a pathway for ingress of cooling water into the weld joint. Sustained high pressure exerted by the water in a localized region leads to initiation of cracking which gets accentuated by the presence of welding defects such as a voids. The propagation of the crack then takes place along the weaker weld bead/base metal interface, eventually leading to crack opening on the surface. Thus, this work highlighted that in the absence of any identifiable correlations between the tuyere failures and abnormalities in BF operating conditions, the most critical factor affecting tuyere performance and service life is its design and quality of its weld joints.

The present article focuses on incorporating mill scale, a steel plant solid waste, into the iron ore pelletization process. The characterization results indicated that the mill scale contained about 71% of Fe and predominantly consists of magnetite and wustite mineral phases. A detailed pelletization study is conducted using the mill scale at different proportions (0%, 10%, 20%, 30%, and 40%) in the feed blend. The impact of mill scale addition on various pellet properties, such as drop number, green and dry compressive strength and moisture content of green pellet, Cold Compressive Strength (CCS), porosity, Swelling Index (SI), Reduction Degradation Index (RDI), and Reducibility Index (RI) of fired pellets, has been investigated. Further, pellet mineralogy is analyzed using X-ray Diffraction and optical microscopy. Experimental results indicate that the mill scale addition of 10% in the feed mix leads to an improvement in pellet strength (CCS) achieving a CCS of 288 kg/pellet with about 24% porosity, 18% SI, 71% RI, and 2.5% RDI. However, a further increase in mill scale negatively affected the pellet properties. Further, the potential of coke rate reduction by the addition of mill scale is also studied in detail. Based on the experimental outcomes, the addition of the mill scale by 10% is beneficial in terms of effectively utilizing mill scale as well as improving the iron ore pellet properties. Graphical Abstract