The Researchon Occurrence Of Defects Due To Inclusions In Carbon Manganese Steel

Nuclear power has beenwidely usedas clean energy, and carbon manganese steel pipeis the key element in the nuclear power plant. Steel pipe must have high property forfulfilling the requirements of the plant, but cracks have often occurred on the surface dueto the inclusions during the rolling of steel pipe. Therefore, we have researched thisproblem by experiments and simulations, which could be reference of producing and haspractical meaning.Inside the inclusion, the stress and strain fields have been found uniform throughmechanics calculation; on the other hand, the mechanics calculationshave alsodemonstrated that the stress surrounding the inclusion is sharply high, this calculationresult accords with the finite element simulation later.Based on the material property of P280GHcarbon manganese steelgetting fromexperiments, the macroscopic coupled thermal-mechanical finite element models ofinclusions have been built. The results of simulations have demonstrated that it genuinelyexists high stress and strain zone around the inclusion, the stress is much higher than theboundary stress, even higher if there are two inclusions, and unusual stress concentratingzone will appear, it is exactly this extraordinary high stress that is responsible for thedefects of metal.Then we have built a crystal plasticity finite element model. The results of stress andstrain have demonstrated that it has high stress and strain in the grain boundary inside thepolycrystal, while the results of slip systems have shown that the most remarkabledeformations are on the surface of polycrystal. Therefore, on the surface of P280GHcarbon manganese steel, it is easier to arise surface crack and other defects, and thephenomena of defects has been explained, and it has directive meaning for the practicalproducts.