Research On Weldability And Welding Repair Procedure Of30CrNi3MoV Steel

Pump body is an important part of oil exploration equipment, the work of the body issimilar to the pressure vessel head, but the work environment is more severe, therefore,high performance is required for pump head body to ensure stable production. Low alloyhigh strength steel has high strength, high toughness and good comprehensiveperformance. It is widely used in national defense and civil area. Currently, most of thehead body materials are using high strength low alloy steel. There will be the size oftolerance and cracks in the manufacture and use of the process of Pump body. Weldingrepair can be quick and economical to solve these problems."low-intensity match" electrode CHE857CrNi is used for welding30CrNi3MoV steel.Y groove cracking test is carried out to evaluate the weldability. This paper compares theeffects of different preheating temperature on microstructure, hardness, and analyzes theinfluencing factors of welding cold cracking. It points out that when it is cooling fast, theHAZ near the fusion line is easier to generate hardened martensite and more PF appearsalong the grain boundaries of the weld zone near the fusion, which is easy to cause cracks.Crack is along the weld line direction，extending to the weld area. The fine ferrite in weldzone is beneficial to prevent crack propagation. The morphology and organization of allarea are studied. We have developed process parameters according to the weldability.Butt welding and surfacing welding experiments are carried out to simulate the pumpLI H FSH]’s crack and tolerance repairing, by means of tensile strength test, impacttoughness test, microhardness test and microstructure analysis, the influence of differentprocedures to the microstructure and performance are studied. Through data calculation,we formulate welding thermal simulation corresponding to the actual welding. The impactof different welding heat thermal cycling on organizational performance is analyzedin-depth and determine the best preheat temperature heat input of high strength low alloysteel. The fracture behavior of welded joints and fracture characteristics is analyzed, thecause of fracture toughness and impact tests on quasi-cleavage fracture is explained, theproperties of the joint is assessed in combined with microstructure.