advantages of casting advantages and disadvantages of hot-rolled seamless steel ...

by:Hanway     2019-08-21
This improvement is mainly reflected in the improvement of the rolling direction to a certain extent, and the steel is no longer of the same sex;Bubbles, cracks and looseness formed during pouring can be welded at high temperature and high pressure.Large diameter magnetic particles or penetration tests can be effective surface defects found in surface cracks, folds, heavy leather, hair line, fine holes.For magnetic materials, because of their high detection sensitivity, the magnetic particle detection method should be given priority;For non-For example, stainless steel seamless steel pipe, the penetration test method is adopted.When fewer ends are removed from the reserve edge, both end detection may not be effective due to structural detection means, and the terminal is most likely to have some cracks or other defects.If the large-There is a potential tendency to crack at the diameter seamless end, and the welding thermal influence device also has the possibility of producing crack expansion.Therefore, it should be noted that after testing some seamless steel pipe welding areas, the defects at the end of the expansion pipe should be detected.Online OHS seamless carbon steel pipe, the insulation may have penetrated into the site when it is damaged or rainy, pay attention to the penetration test to identify defects such as stress corrosion cracking or point corrosion.After hot rolling, no steel insideThe inclusion of metal (mainly sulfur and oxide, and silica) is pressed into thin sheets and layered (sandwich) occurs.The stratification in the thickness direction of the tensile properties of the steel is significantly deteriorated, and there may be a contraction of the sandwich tearing weld.Welding local strainThe induced contraction of the yield point strain is often several times larger than the load caused by the strain;Residual stress caused by uneven cooling.In the absence of external forces, the residual stress comes from the internal balance of the stressVarious residual stresses such as steel sectionThe section size of the steel is general, and the residual stress is large.Although residual stress comes from equilibrium, it still has a certain influence on the performance of steel members under load.Deformation, stability, resistanceFatigue may have adverse effects.Hot-Steel products, the control of the thickness and width of the edges in this face is very poor.What we are familiar with is hot expansion and cold contraction. since the beginning of hot rolling, the length and thickness are standard. Finally, there will be some negative differences when cooling. this negative difference edge is wide and wide, the thicker the more obvious the performance.
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