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Weld Cracking of oxygen lance nozzle


, Scan and metallographic examination of fracture 2.3 Chemical analysis of chemical composition analysis results are listed in Table l. The results showed that the steel base material for the Q235A; copper base metal equivalent of the chemical composition of No. l oxygen-free copper, silicon bronze welding is. 2.4 Determination of the mechanical properties of copper weld a crack-free part of the steel were tensile and bending test, the results are shown in Table 2. 2.5 crack perpendicular to the direction of the fracture analysis of pull-off specimens with crack, Figure 2 shows the welding macro-morphology of the fracture gap, Figure 3 shows the fracture morphology. Can be seen throughout the section, the fracture has two distribution patterns, population 121, definitely the right pull-Hao Hou and other r * Oxygen lance nozzle weld cracking bad 2 points off the mechanical properties of weld fracture in Figure 2 the results of macro-morphology of 20 × Figure 3 General view of fracture morphology was 154 × the dimple-like morphology, while the section on the left side of the distribution of cracks along the grain boundary, is a typical intergranular fracture. 2.6 EDS spectrum of grain boundary composition analysis conducted, the results shown in Figure 4. The figure shows, in addition to the base outside of copper, iron, oxygen peaks higher,[link widoczny dla zalogowanych], indicating a grain boundary along the copper anomaly. 2.7 Metallographic examination weld cracks with an optical microscope, has shown that the surface of the weld cast structure, shown in Figure 5. For the next weld crack double-crystal phase was distributed in the matrix like a rose on the gray-blue granules (FeSi) 23456789keV spectrum analysis Figure 4 Figure 5 looking weld surface was scattered organizations l0O × HCl aqueous ferric chloride corrosion Figure 6 next to the weld crack was destroying tissue 5oox chloride as stiff hinge loss HCl solution Hou Hao et al: Oxygen grab the nozzle of the weld cracking phase, while there are still brittle phase grain boundary precipitates, shown in Figure 6.3 to discuss the above test results, that the Department of oxygen lance nozzle weld cracking caused by improper welding. Steel base metal and copper base metal stitching, the bottom did not stay in space, was sharp V-shaped; other groove angles through the small, have both contributed to lack of fusion between the weld and steel. Surface as a result of welding cast, their strength, ductility and toughness is not good,[link widoczny dla zalogowanych], poor adhesion. When the oxygen lance nozzle subjected to axial force, the crack in the weld surface of the first base metal and steel table at the junction between the generation that formed the crack source. Oxygen lance nozzle in the alternating cycle of work stress, the crack tip have a greater stress concentration, when this stress is greater than the critical crack tip stress expansion, the crack will be extended. On the one hand, due to the fusion welding of steel parent material well, it sets and the weld junction between the small force, the force to become the weak link, so the crack will follow the steel and weld joint surface between the expansion of This process is carried out again and again until the expansion to the weld toe. On the other hand, due to the cooling in the welding process, the cooling rate is too large can not be spread evenly to make components, the first pure solidified Taijin, after solidification of the alloy impurities, these impurities formed brittle phase has a lower eutectic the melting point, they were easily enriched in the grain boundary network distribution, constitute weak areas. So that under the action of external forces, the first cracks will be generated within the silicon bronze welding weak regional expansion. 4 Conclusion (1) before welding copper and steel base metal stitching, the bottom did not stay in space, was sharp V-shaped, in addition, the slope through the small mouth, resulting in base metal and steel between the weld is not fusion, with force is small, So the first cracks in the weld toe source. (2) welding process, the cooling rate too fast to spread uneven composition, resulting in the internal organization of non-uniform silicon bronze welding. One pair in the matrix phase of the grain boundary network on a continuous brittle phase precipitates to form weak areas. Under the action of external forces,[link widoczny dla zalogowanych], the crack extended to the internal silicon bronze welding. (3) by adjusting the welding process, an increase of Q on both sides of the base metal and the groove angle of the gap, increasing the penetration rate of the steel base metal and weld metal of the end table large enough force, thereby reducing the production of weld toe crack tendencies. Oxalic acid: nitric acid solution of oxalic acid Wing: f nitric acid, tartaric acid ethyl glycol solution of tartaric acid L water demand requirements nitric acid solution of citric acid citric acid solution: distilled nitric acid 2mLlOOraL never wipe 3 ~ 5s, rinse with hot water or cold water casting magnesium alloy display wrought magnesium alloy case and wipe 3 ~ 20s, rinse with hot water 0.5 to 2. OmL1OOmLlmL smear 3 ~ los, rinse with hot water wipe 75mLlOOmL2g1O0rnL5 ~ lOmL1OOmLlOOmL1 ~ 8mL l0 ~ 20s wipe clean 5 ~ 15s a few seconds to several minutes to display magnesium nitrate and magnesium 5mL sets box can be displayed with varying grain 0.5mL organization. B shows the general organization of reagents for magnesium alloys after aging box. Display shows the grain boundary and organizational units of aluminum,[link widoczny dla zalogowanych], zinc, manganese magnesium showed deformed magnesium manganese box sets boxes and boxes of copper alloys, magnesium and magnesium too blunt box sets the number of magnesium and magnesium cast and forging state house of gold 123 *

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