关键词: 耐沟状腐蚀性, 退火, 碳化物, 再结晶, 采暖系统

Abstract: Through the research on the phenomenon of the resistance to grooving corrosion, and combining with the production equipment capacity, six kinds of steel strip chemical compositions and six kinds of annealing processes were designed. The effect of cold rolling annealing process on the properties of grooving-corrosion resistant steel strips for heating system was studied by means of metallography, SEM, tensile test, and salt spray test. The results show that the annealing at temperature lower than Ac₁(650 and 700 ℃) can not change the genetic structure of the original grain boundary of cold-rolled ferrite, under such conditions the recrystallization of cold rolled α phase does not grow sufficiently, and the polymerization and growth of carbides are also insufficient. When the annealing temperature reaches about Ac₁(750 ℃), the solid solving of carbon increases, leading to recrystallization and growth of α phase as well as the polymerization of precipitates, resulting in excellent ductility, which is very beneficial for deep drawing. When the annealing temperature is between Ac₁-Ac₃(850 ℃), α→γ phase transformation and recrystallization occur, and the best softening effect can be obtained. While for the Ti-bearing tested steel, the plastic strain ratio r value tends to decrease with the decrease of annealing temperature. The addition of Al is conducive to increase the resistance to grooving corrosion, but the Cr addition has the opposite effect. Using two-stage annealing process for industrial production can get grooving-corrosion resistant products for heating systems with excellent appearance and properties.

Key words: grooving-corrosion resistance, annealing, carbides, recrystallization, heating system