Executive Standard: ASTM.DIN,JIS,GB
|PRODUCT||OUT SIDE DIAMETER||THICKNESS|
|Black Round Steel Pipe||0.4645-2.9921||11.8-76||0.0118-0.0787||0.3-2.0|
Theoretical calculation method of 40cr steel pipe plant
The 40cr steel pipe is a circular steel pipe having a hollow section and no joint at the periphery, and is formed by piercing a solid pipe blank into a capillary tube, and then hot rolled, cold rolled or cold-rolled.
The 40cr steel pipe is a circular steel with a hollow section and no joints around it. The 40cr steel pipe plant is made of a solid tube blank through perforation and then made by hot rolling, cold rolling or cold drawing. The 40cr steel pipe has a hollow section. Compared with a solid steel such as round steel, the steel pipe has a lighter weight when it has the same bending and torsional strength, and is an economical section steel.
Calculation formula for weight per metre of 40cr steel pipe: 0.02466* wall thickness* (outer diameter - wall thickness)
40Cr steel pipe
According to the standard GB/T 3077-2008: chemical composition (mass fraction, %) C 0.37~0.44, Si 0.17~0.37, Mn 0.50~0.80, Cr0.80~1.10, Ni≤0.30.
Sample blank size (mm): 25
First quenching heating temperature (°C): 850; coolant: oil
Second quenching heating temperature (°C):-
Tempering heating temperature (°C): 520; coolant: water, oil
Tensile strength (σb/MPa): ≧980
Yield point (σs/MPa): ≧785
Elongation after break (δ5/%): ≧9
Area shrinkage (ψ/%): ≧45
Impact absorption work (Aku2/J): ≧47
Brinell hardness (HBS100/3000) (annealed or high temperature tempered state): ≦207
40Cr quenching process
40Cr quenching 850 ° C, oil-cooled; tempered 520 ° C, water-cooled, oil-cooled. The surface quenching hardness of 40Cr steel pipe is HRC52-60, and the flame quenching can reach HRC48-55.
40cr steel pipe plant nitriding treatment
40Cr is a nitrided steel, and its elements are favorable for nitriding. After 40Cr is nitrided, high surface hardness can be obtained. After 40Cr quenching and tempering, the hardness of nitriding treatment can reach HRA72~78, which is HRC43~55.
Nitrided workpiece process route: forging - annealing - roughing - quenching - finishing - stress removal - rough grinding - nitriding - fine grinding or grinding.
Since the nitrided layer is thin and brittle, it requires a higher strength of the core structure, so the tempering heat treatment is first performed to obtain the tempered sorbite, and the mechanical properties of the core and the quality of the nitrided layer are improved. Soft nitriding is active nitriding, and gas nitriding is more commonly used.
This steel is tempered by 40cr steel pipe mill to manufacture mechanical parts subjected to medium and medium speed work, such as the steering knuckle of the car, the rear axle and the gears, shafts, worms, spline shafts, tip sleeves, etc. After quenching and medium temperature tempering, it is used to manufacture parts subjected to high load, impact and medium speed work, such as gears, spindles, oil pump rotors, sliders, collars, etc.; used for manufacturing heavy bearing after quenching and low temperature tempering Load, low impact and wear-resistant parts with a solid thickness of 25mm or less on the cross section, such as worm, spindle, shaft, collar, etc.; after quenching and tempering and high-frequency surface quenching, it is used to manufacture high surface hardness and resistance. Parts that are abrasive without major impact, such as gears, sleeves, shafts, spindles, crankshafts, spindles, pins, connecting rods, screws, nuts, intake valves, etc. In addition, the 40cr steel pipe plant is suitable for the manufacture of various transmission parts for carbonitriding, such as gears and shafts with large diameter and low temperature toughness.
15CrMo seamless steel pipe welding material
15CrMo seamless steel pipe can be recycled, in line with the national strategy of environmental protection, energy saving and resource conservation. The national policy encourages the expansion of the application field of 15CrMo seamless steel pipe.
At present, the proportion of 15CrMo seamless steel pipe consumption in China accounts for only half of the total amount of steel, and the use of 15CrMo seamless steel pipe expands to provide a broader space for the development of the industry. According to the research of 15CrMo seamless steel pipe branch of China Special Steel Association, the demand for high-pressure 15CrMo seamless steel pipe long-term in China will increase by 10-12% annually.
Seamless steel pipe
Due to different manufacturing processes, it is divided into two types: hot-rolled (extrusion) seamless steel pipe and cold drawn (rolled) seamless steel pipe. Cold drawn (rolled) tubes are divided into two types: round tubes and shaped tubes.
a. Process overview
Hot rolling (extrusion seamless steel pipe): round tube billet → heating → perforation → three-roll cross-rolling, continuous rolling or extrusion → pipe removal → sizing (or reducing diameter) → cooling → blank tube → straightening → water pressure Test (or flaw detection) → mark → into storage.
Cold drawn (rolled) seamless steel pipe: round tube billet → heating → perforation → head → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → Hydraulic test (inspection) → mark → storage.
15CrMo seamless steel pipe is a pearlitic heat-resistant steel with high heat strength (δb≥440MPa) and oxidation resistance at high temperature, and has certain resistance to hydrogen corrosion. Due to the high content of Cr, C and other alloying elements in the steel, the hardening tendency of the steel is obvious and the weldability is poor.
15CrMo seamless steel pipe weldability
According to the working characteristics of the welding property of 15CrMo seamless steel pipe, according to the previous experience, we have selected two schemes for the welding test with reference to the welding process card provided by foreign countries.
Scheme I: Welding preheating, using ER80S-B2L welding wire, T1G welding base, E8018-B2 welding rod, electrode arc welding cover surface, local heat treatment after welding.
Scheme II: ER80S-B2L welding wire, T1G welding primer, E309Mo-16 welding rod, welding rod filling arc welding cover surface, no heat treatment after welding. The chemical composition and mechanical properties of the welding wire and welding rod are shown in Table 1.
Post-weld heat treatment
The test piece welded by the scheme I shall be subjected to local high temperature tempering after welding. The heat treatment process is as follows: the heating rate is 200 ° C / h, the temperature is raised to 715 ° C for 1 hour and 15 minutes, the cooling rate is 100 ° C / h, and the air is cooled to 300 ° C. Specifically, the JL-4 crawler type electric heater (1146×310) is used to wrap the weld seam, and the aluminum silicate cotton layer is used for heat preservation. The thickness of the insulation layer is 50 mm, and the temperature control adopts the DJK-A type electric heater automatic temperature controller.