October 12, 2022
Stainless steel heating temperature range is narrow
Stainless steel heating temperature range is narrow, the thermal conductivity and carbon steel is also a big difference. 300 series of austenitic stainless steel smls pipe because of its good overall performance in the boiler, petrochemical industry has been widely used. In the heating system design, in order to ensure the quality of heating, heating speed must be controlled within a reasonable range. Since the 300 series of stainless steel seamless pipe since the emergence of a large number of production and wholesale duplex stainless steel processing enterprises, the main production process routes are: "perforation + multi-pass cold-rolled (pull)" or "squeeze + multi-pass cold ) ". Especially in the boiler industry as an important base for heat exchangers to use.
The complicated process brings long problems such as long production process, long production cycle, low output, low yield, high cost and pickling pollution environment. Online water cooling is different from the off-line solid solution, online water cooling without again on the steel pipe heating, how to use the deformation of waste heat for on-line processing to ensure that the mechanical properties of steel pipe to meet the follow-up processing requirements. Due to the cold working hardening and surface quality of stainless steel, a series of treatments such as annealing heat treatment, pickling and lubrication are required before each cold rolling or cold drawing.(2) Deformation process parameters set to be re-selected, significantly different from the carbon steel pipe. The use of online water heat treatment, stainless steel seamless steel pipe into the water temperature control in the 920 ~ 950 , which can effectively ensure that all aspects of performance to meet the requirements of the subsequent cold processing, to achieve the purpose of replacing the field of solid solution.
At high temperatures, too long high temperature holding time and high insulation temperature easily lead to blank grain grain structure to produce δ ferrite and the phenomenon of grain growth serious phenomenon, resulting in defects in the steel pipe surface. Compared with the carbon steel pipe, the stainless steel pipe has the characteristics of large deformation resistance, large thermal expansion coefficient, low thermal conductivity in the low temperature range, wide width and easy to stick, and the setting of the process parameters Carbon steel pipe is significantly different.In the production of austenitic stainless steel seamless pipe, the following technical difficulties
1) To determine the stainless steel pipe blank heating process to develop a certain degree of difficulty.(3) Stainless steel pipe online water heat treatment technology needs to be established.
1) To determine the stainless steel pipe blank heating process to develop a certain degree of difficulty.(3) Stainless steel pipe online water heat treatment technology needs to be established. Due to the limited amount of deformation per pass, to produce finished products often need more than the cold or cold drawn.Stainless steel has excellent corrosion resistance, formability and a wide range of strength and toughness in a wide range of characteristics, in heavy industry, light industry, daily necessities industry and building decoration and other industries are widely used.Design and development of "hot rolling (perforation + sizing) + on-line water cooling" Φ89mm production of stainless steel seamless steel pipe blank production process, can reduce the middle of cold rolling (pull) pass, greatly simplifying the process.
Posted by: incoloytube at
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The coexistence of these two types of elements
Performance of the stainless steel except for process factors, mainly depends on the composition of its internal organization, and is the sum of the various alloy elements in the steel constituting the stainless steel tissue.If the stable austenite elements role residing in the main aspects, the organization of stainless austenitic-based, rarely even no ferrite; if their role is not yet make austenite at room temperature maintained until then, this unstable austenite upon cooling, martensite transformation occurs, and the steel tissue is martensite; if the ferrite element is formed into the main aspects, steel tissue is mainly in ferrolites.
Such as in the ferritic steels of the chromium-containing 18% of the low-carbon (0.005% of boron powder, can make the corrosion resistance of steel in boiling 65% acetic acid wholesale martensitic stainless steel be improved; added trace (0.12% or less of carbon) adding 8% nickel, the ideal pure austenite structure is obtained at room temperature, this steel is that people generally said non-magnetic stainless steel. but the stainless steel containing boron will cause reduced ductility and toughness.
Because of adding these elements, resulting in the change of the internal organization of the steel, so that make the steel have special properties.0007%) of boron in the austenitic stainless steel can make heatstate plasticity be improved; boron to improve the hot strength of steel have good effect, make the hot strength of stainless steel be significantly improved; boron chromium-nickel austenitic stainless steel has a special use in the atomic energy industry.0006 to 0.. Therefore, the performance of stainless steel, in the final analysis, is mainly determined by the alloy elements.
According to metal powder supplier, a lot of steels exist several or even more alloying elements, When several elements coexist on the stainless steel this continuum, decided stainless organization is the sum of the influence of various elements. The disadvantage of this type of stainless steel is low mechanical properties, sensitive to intergranular corrosion and stress corrosion, but by the right amount of alloy additives or process measures can improve or eliminate. Various elements impact on the organization of stainless steel, according to its commonality, to sum up, basically belong to two categories: one is the formation of stable austenite elements, they are carbon, nickel, manganese, nitrogen, copper, the role of carbon and nitrogen is the greatest; the other is formed of the ferrite element, which is a chromium, tungsten, molybdenum, niobium, silicon, titanium, vanadium, aluminum or the like, this type elements form ferrite, such as chromium is to be compared, the role of the other elements were larger than the chromium. Adding the right amount of nickel in the chromium grade stainless steel matrix elements.
The coexistence of these two types of elements in stainless steel, stainless steel tissue depending on the results they influence each other. Chromium-nickel stainless steel such as the same amount of chromium ferritic or martensitic acidproof stainless steel comparison, not only has a higher corrosion resistance, and more important to mention that they have a good cold deformation so that hardening and welding properties, in ambient temperature or low temperature with high plasticity and toughness, and excellent performance of the non-magnetic, etc. High-chromium ferritic stainless steel was added 0
Posted by: incoloytube at
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