The defects of mild steel pipe

The defects of mild steel pipe under a reducing atmosphere or in a vacuum protection, after high temperature solid melting and rapid cooling to get the stainless steel tube, requiring the inner surface has a very good surface roughness and cleanliness, is a comprehensive consideration of organizational stability corrosion resistance and workability of the pipe.

The defects of mild steel pipe are following below Scarring One of the steel surface defects, the performance of the product surface scar-like foil. Often has tongue, block or scaly and irregular distribution. Scarring sizes, shades ranging from below often inclusions. Rolling scarring resulting scar is called rolling, the distribution location, shape and size substantially the same, there are many defects in the oxide skin beneath. General metallurgical products surface does not allow scarring. White spot In the acid leaching of transverse specimens showed white dots of varying sizes of internal defects. White irregular shape, smooth and slightly raised, mostly in the central part of a larger size and high alloy content rolled and forgings. The reason is that the chemical composition of white uneven segregation and aggregation of certain alloying elements. It is not easy to corrosion due to defects in the acid leaching appear as white spots on the specimen. Approach is adopted to prevent leukoplakia refining, argon stirring to evenly ingredients, using ingot casting technology or control the cooling rate to prevent fluid analysis. Pipe lamination Structural separation of large organizations present on the metal substrate, is an internal defect metal plastic processing products. Separating surface parallel to the processing surface, the longitudinal and cross sections showed a long crack, there is a small amount of non-metallic inclusions in the cracks and segregation, destroy the integrity of the metal substrate. Stratification is due to shrinkage, the crack, bubble plastic processing defects by extending, elongated, and failed weld formation. Hair crack One of the steel surface defects, the performance of the product surface hairy lines. Shorter than shallow cracks along the rolling direction dispersed or in clusters. Hairline is the product generally allow defects, but its depth should comply with the relevant standards. Banded orientation One flaw in the steel, hot rolled low carbon steel in the microstructure, are arranged in parallel along the rolling direction, a layered distribution of ferrite and pearlite grains grain just like strip. This is due to occur in the steel during cooling after hot rolling in the ferrite by the priority and non-metallic inclusions dendritic segregation strip extending from the formation, resulting in the formation of ferrite strips, strips of ferrite phase transformation between pearlite, the two phases into the layer distribution. So the presence of the band structure of the uneven structure of the steel and the impact properties of the steel, the formation anisotropy, lower ductility of steel, and reduction in toughness, resulting in undesirable cold bending, stamping scrap rate, easy deformation during the heat treatment of steel adverse consequences. Surface defects In steel and non-ferrous alloy material surface and affect the quality of products of various flaws in general. Many types of surface defects, mostly in the morphology of the defect to name, and some of its causes named. Production processes often to produce defective products surface defects into two categories. One is steel bad defects, such as separation, scarring, crack, crack, hairline, bubbles, etc. Most of these defects are caused due to poor quality of the ingot. Another flaw is poor machining operations, including folding, ears, pitting, convex hull, scratches, dents, pressed into the oxide scale, burrs, etc., these defects are generated in the process of plastic plus. Burr One of the steel surface defects, manifested as cold cuts, hot saw steel ends are missing or flame cutting burr, when extruded pipe welds have excess metal. Cold cut products depends on the thickness of the ends burr gap between the blade. General product to allow a certain degree of glitches exist; But inside and outside burr pipe must be scraped off.

Categories: News