1. (1). 15CrMo alloy steel pipe: This is a pearlitic heat-resistant steel based on steel, known for its high-temperature strength (δb ≥ 440MPa) and good oxidation resistance at elevated temperatures. It also exhibits some resistance to hydrogen corrosion. Due to the high levels of chromium and carbon in the alloy, this steel has a significant tendency to harden and poor weldability. 2. Welding materials: Considering the welding characteristics of 15CrMo steel, and based on previous experience, two welding schemes were selected for testing, referencing foreign welding guidelines. Option I: Preheating was applied, using ER80S-B2L welding wire for TIG welding as the base layer, followed by E8018-B2 electrode for arc welding as the cover pass, and local post-weld heat treatment. Option II: ER80S-B2L welding wire for TIG base layer, E309Mo-16 welding rod for arc welding as the cover pass, with no heat treatment after welding. 3. For the welding of thick-wall high-pressure 15CrMo steel pipes, two welding methods were used: (1) Scheme I: Base metal temperature 550/530°C, 50% qualified, 84.8 MPa, 162 MPa, 135.6 MPa. Option II: Base metal temperature 525/520°C, 50% qualified, 79.4 MPa, 109.2 MPa, 96.7 MPa. From the tensile test results, it can be seen that the tensile specimens of both schemes broke in the base metal, indicating that the weld's tensile strength is higher than that of the base material. The bending tests were allåˆæ ¼, showing good plasticity of the weld. According to the impact toughness test results in Table 5, the impact toughness of Scheme I is significantly higher than that of Scheme II, proving that the post-weld heat treatment in Scheme I is ideal. High-temperature tempering not only improves the joint structure and performance but also ensures proper matching of toughness and strength. From the room temperature mechanical properties, both recommended welding processes are suitable for on-site construction. Scheme I uses an electrode similar in composition to the base metal, ensuring good compatibility between the weld and the parent metal. The weld should maintain high heat strength and remain stable even after long-term use at high temperatures. However, the challenge lies in the strict requirements for post-weld heat treatment. Improper control of tempering temperature, holding time, or heating/cooling rates may reduce the weld bead performance. Scheme II uses austenitic stainless steel electrodes, which allow the omission of post-weld heat treatment. However, due to the different thermal expansion coefficients between the weld and the base metal, carbon diffusion and migration may occur during prolonged high-temperature operation, leading to damage in the fusion zone. Therefore, from a reliability standpoint, Scheme I is more stable for field applications. 4. The welding of thick-wall high-pressure 15CrMo steel pipes using the two proposed schemes is feasible. To ensure that the weld bead performance matches the base metal and maintains high heat strength, Scheme I performs better. The key is to apply it carefully when heat treatment cannot be performed.
Stainless Steel Pump Head Plunger Metering Pump
*Sealed design which enhance the safety level and reduce the leakage problem
*Variety type of pumps, the capacity is up to 30000L/H
*Metering accuracy is around ±0.5% during within 10-100% stroke length range
* The capacity flow up to 200L/H
*The pressure up tp 50Mpa
*The flow can be adjusted from 0-100% while it's running or stopped.
* Different material of the liquid end to meet of different liquid.
* Double or Triple pump heads are available.
* Liquid temperature range is not over than 250 degree.
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