Q1: Hvad er den vigtigste produktionsproces for tykvæggede sømløse rør?
The production of thick-walled seamless pipes includes the following key steps: round billet heating (1200±50℃) → piercing (pressure piercing or oblique rolling piercing) → elongation rolling (such as Assel rolling mill) → sizing → heat treatment (normalizing or quenching and tempering) → straightening → non-destructive testing → water pressure test. Among them, the piercing link is particularly critical for thick-walled pipes, requiring large-diameter billets (such as Φ350mm) and multiple rolling passes. Modern continuous rolling mills (such as MPM) can produce seamless pipes with a diameter of Φ60-460mm and a wall thickness of up to 120mm, and the production efficiency is 3 times higher than that of traditional Metoder .
Spørgsmål 2: Hvad er fremstillingsprocesskarakteristika for tykvægget lige søm nedsænket lysbuesvejsede rør (SAWL)?
SAWL thick-walled pipe production process: ultrasonic flaw detection of steel plate → milling edge (groove 30℃±2℃) → JCO or UOE forming → pre-welding (TIG primer) → multi-wire submerged arc welding (4-5 wires, current 800-1200A) → diameter expansion (1.0-1.2%) → heat treatment (stresslindringsudglødning) . Den nøgleteknologi er at kontrollere svejsningsvarmeindgangen (20-35 kJ/cm) for at undgå haz-omfavnelse, og bruge røntgenstråle + ultrasonisk dobbeltfejldetektion for at sikre svejsningskvalitet {{12} denne proces er egnet til rør med en diameter af φ 406-1626 mm og en våd 20-60 mm, med en produktionseffektivitet på ca. 1-2 meter/minut .
Spørgsmål 3: Hvad er de vigtigste kontrolparametre til varmebehandling af tykvæggede stålrør?
Heat treatment of thick-walled pipes needs to be strictly controlled: normalizing temperature (Ac3+30-50℃, such as 890±10℃ for 20# steel), holding time (1 hour for every 25mm of wall thickness), cooling rate (air cooling ≤3℃/s); water cooling rate during quenching needs to be >30℃/s to avoid ferrite precipitation; tempering temperature (such as 680±10℃ for 15CrMoV steel) and time (wall thickness × 2.4 minutes/mm). For extra-thick walls (>100 mm), kræves differentieret temperaturvarmebehandlingsteknologi for at sikre kerneydelse . Hårdhedsgradienten efter varmebehandling skal kontrolleres inden for området ± 20HBW .
Spørgsmål 4: Hvad er den resterende stresskontrolmetode i produktionen af tykvæggede stålrør?
Overdreven resterende stress kan føre til deformation eller stresskorrosion . Kontrolforanstaltninger inkluderer: varm retning efter rulling (600 ± 50 grader), samlet annealing (580-650 grad isolering til4-8 timer), vibrationsaldering (VSR) behandling, mekanisk ekspansion (1.0-1.5% deformation) og eksplosive stress. relief. For welded thick-walled pipes, multi-layer multi-pass welding + interlayer hammering process is required. Residual stress detection can be carried out by X-ray diffraction method or blind hole method, requiring surface residual compressive stress>=-200MPa.
Q5: Hvad er de særlige krav til kvalitetsinspektion af tykvæggede stålrør?
In addition to conventional inspections, thick-walled pipes need to add: Z-axis tensile test (section reduction rate>=35%), step cooling test (assessment of temper brittleness), UT flaw detection (dual crystal probe detection of internal defects), TOFD detection (quantification of weld defects) and hardness scanning (full-section Brinell hardness test). For Atomkraftrør, kornstørrelsesvurdering (grad 5-8) og renhedsanalyse ([O] mindre end eller lig med 20 ppm) er også påkrævet . vægtykkelsesmåling kræver en højfrekvent ultrasonisk tykkemåler med en nøjagtighed på ± 0 {. 1mm.
