Specifications: diameter: 320 to 127 mm thickness: 0.4 to 12.7 mm Length: 6 m above, and, in accordance with customer demand, supply and other specifications of steel pipe

15CrMo alloy steel pipe,15CrMo alloy tube


15CrMo alloy steel pipe

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15CrMo weldability
15Crmo alloy pipe mechanical properties
15CrMo alloy steel pipe weight formula:
15CrMo alloy steel pipe dimensions and tolerances for
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  15crmo alloy steel pipe : steel Department of pearlite heat-resistant steel, high hot strength (δb ≥ 440MPa) and oxidation resistance at high temperatures, and has a certain resistance to hydrogen corrosion. As the steel contains a higher content of Cr, C, and other alloying elements, the steel hardened tendency obvious, poor welding.
 
15CRMO alloy steel pipe

15CRMO alloy steel pipe

Edit this paragraph15CrMo weldability

  Welding materials: the 15CrMo steel welding work characteristics, based on past experience with reference to foreign welding process card, we selected two programs for welding test.
 
  The program Ⅰ: welding preheat ER80S-B2L wire, T1G welding primer E8018-B2 electrodes, SMAW cover the surface, the local post-weld heat treatment. Option Ⅱ: ER80S-B2L wire T1G welding primer E309Mo-16 electrodes, welding rod filled electric arc to cover up, post-weld heat treatment. Wires and rods for chemical composition and mechanical properties are shown in Table 1.
 
  15crmo alloy steel tube chemical composition:
 
  
Material C Si Mn Mo Cr
15CrMo 0.12 to 0.18 0.17 to 0.37 0.40 ~ 0.70 0.40 ~ 0.55 0.80 ~ 1.10
 

Edit this paragraph15Crmo alloy pipe mechanical properties

 
  
Trademark Specimen blank dimension / mm Heat treatment Mechanical properties Brinell hardness steel annealing or tempering supply state HBS100/3000 Use
Quench Tempering Tensile strength Yield point Elongation rate δ5 (%) Reduction of area ψ (%) Impact absorbed energy Aku2 / J
First quenching Second quenching Coolant Heating temperature ℃ Coolant
Heating temperature ℃
15CrMo 30 900 - Air 650 Air ≥: 440 ≥: 295 ≥: 22 ≥: 60 ≥: 94 ≤: 179 Used in high temperature environments, and withstand a certain pressure
 Chemical composition and mechanical properties of the weld material
 
  Model C Mn Si Cr Ni Mo the SP δb / Mpa δ%
 
  ER80S-B2L ≤ 0.05 0.70.41.2 <0.20.5 ≤ 0.025 ≤ 0.025 ≤ 500 25
 
  E8018-B2 0.070.7 0.3 1.1 0.5 ≤ 0.04 ≤ 0.03 550 19
 
  E309Mo-16 ≤ 0.12 0.5 ~ 2.5 0.9 22.0 ~ 25.0 12.0 ~ 14.0 2.0 ~ 3.0 ≤ 0.025 ≤ 0.035 550 25
 
  Preparation before welding
 
  The specimen with the the 15CrMo steel pipe specifications φ325 × 25, groove type and dimensions shown in Figure 1.
 
  With the angle grinder before welding inside and outside the groove and the groove edge 50mm within polished to expose the metallic luster, and then cleaned with acetone.
 
  Specimen horizontal fixed position, and their counterparts in a gap of 4 mm, GTAW circumferentially uniform spot welding six solid at point length should be not less than 20mm. The electrode according to the specification of Table 2 for baking.
 
  2 electrode baking specification
 
  The electrode model baking temperature holding time
 
  E8018-B2 300 ℃ 2h
 
  E309Mo-16 150 ℃ 1.5h
 
  The 3 welding process parameters
 
  Press the need for preheating before welding program Ⅰ preheat temperature formula, according to calculations made Tto-Bessyo:
 
  To = 350 √ [C] -0.25 (° C) Where To - preheat temperature, ℃.
 
  [C] = [C] x [C] p [C] p = 0.005S [C] x
 
  [C] x = C (Mn Cr) / 9 Ni/18 7Mo/90 formula,
 
  [C] x - component of carbon equivalent;
 
  [C] p - size carbon equivalent; S - the thickness of the specimen (this article in S = 25mm);
 
  [C] x = C (Mn Cr) / 9 7/90Mo = 0.361
 
  [C] p = 0.045 Ze To = 138 ℃
 
  Thus, the preheating temperature preferably 150 ° C. Using oxygen - acetylene flame for heating the specimen using a rough judgment specimen surface temperature (estimate) ink color changes in the pace of tempilstick last point temperature was measured with a semiconductor measuring point should choose at least three points to ensure that the test piece as a whole to achieve the desired preheating temperature.
 
  During welding, the first layer of GTAW primer, to avoid the overhead welding at the back seam depression wire feeder filled wire method, namely wire tube into the gap by counterparts from. The remaining layers welding SMAW welding a total of six layers, each layer a bead. Program Ⅰ and programs II welding parameters are shown in Table 3 and 4. By program I welding
 
  3 program I welding parameters
 
  The name of the weld bead welding method of welding material welding consumables specifications / mm welding current / A Arc voltage / V preheat and inter-layer temperature heat treatment specification
 
  Fight the underlying tungsten plate TIG ER80S-B2L φ2.4 110 12
 
  The filling layer SMAW E8018-B2 φ3.2 5 85 ~ 90 23 ~ 25150 ℃ 715. × 75min
 
  Cover surface SMAW E8018-B2 φ3.2 5 85 ~ 90 23 ~ 25
 
  3 program II of welding parameters
 
  The name of the weld bead welding method of welding material welding consumables specifications / mm welding current / A Arc voltage / V preheat and inter-layer temperature heat treatment specification
 
  Fight the underlying tungsten plate TIG ER80S-B2L φ2.4 110 12
 
  Filling layer electrode arc welding E309Mo-16 φ3.2 90 ~~ 95 22 ~~ 24 / /
 
  SMAW cover surface E309Mo-16 φ3.2 90 ~~ 95 22 ~~ 24
 
  Then, interpass temperature should not be less than 150 ℃, the cooling of the specimen to prevent interruption of welding, welding should be two welders operate alternately insulation slow cooling measures should be taken immediately after welding.
 
  Welding procedure qualification test
 
  JB4730-94 "pressure vessel specimen after welding and non-destructive testing standard 100% ultrasonic testing of welds level I qualified. JB4708 "steel pressure vessel welding procedure qualification standard welding procedure qualification test. The evaluation results are shown in Table 5.
 
  4 welding procedure qualification test results   
 
 
  The pilot programs tensile test Bending test impact toughness test aky (J/cm2)
 
  Tensile strength δb / Mpa fracture site bending angle the surface bend back bend weld fusion line heat-affected zone (the HAZ)
 
  Ⅰ 550/530, the base material 50. Pass Pass 84.8 162 135.6
 
  Program Ⅱ 525/520 base material 50. Pass Pass 79.4 109.2 96.7
 
  Seen from the results of the tensile test, the tensile specimens of the two programs all off the base material, the higher tensile strength than the base material of the weld; bending test all qualified better weld the plastic. Impact toughness test results in Table 5 shows that the program Ⅰ impact toughness is significantly higher than the program the Ⅱ, proof program Ⅰ weld heat treatment specifications ideal, high-temperature tempering not only to improve joint organization and performance objectives, and the toughness of the strength with the appropriate. Seen from the results of room-temperature mechanical properties of the recommended two welding process scheme can be used in the construction site. Ⅰ using the program close to the electrode and the base metal composition, weld properties match with base metal, weld should have a high hot strength the weld not easy to destroy long-term use at high temperatures.The difficulty is post weld heat treatment specifications are more stringent, tempering temperature and holding time and heating and cooling rate is properly controlled it will lead to the weld performance. Austenitic stainless steel electrode welding program Ⅱ, eliminates the need for post-weld heat treatment, but due to the expansion coefficient of the weld and base metal, when the long-term high-temperature work can occur in the diffusion of carbon migration phenomenon, easily lead to weld fusion zone failure occurs. Therefore, the reliability considerations from the use of on-site use of the program I welding more secure.
 
  Conclusion
 
  The 15CrMo steel thick-walled high-pressure pipe welding two welding programs are feasible. In order to ensure that The weld properties match with the base metal has high heat resistance, using programs Ⅰ better, the key is to strictly control the post-weld heat treatment process.
 
  Program Ⅱ Although eliminating the need for post-weld heat treatment, but the possibility can not be ignored weld carbon migration occurs at high temperatures caused by the proliferation of the welds destruction, therefore, can not be carried out only in the post-weld heat treatment only carefully using.
 

Edit this paragraph15CrMo alloy steel pipe weight formula:

  [( OD - Wall Thickness) * thickness] * 0.02466 = kg / m (weight per meter)
 

Edit this paragraph15CrMo alloy steel pipe dimensions and tolerances for

  
Deviation level The standardized outer diameter allowable deviation
D1 ± 1.5% , minimum ± 0.75 mm
D2 ± 1.0% . Minimum ± 0.50 mm
D3 ± 0.75% . Minimum ± 0.30 mm
D4 ± 0.50% . Minimum ± 0.10 mm

 

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