Will the annealing temperature affect the internal structure of stainless steel?

Stainless steel is a typical ultra low carbon nitrogen ferritic stainless steel, widely used in the automotive exhaust system and kitchen utensils and other fields, the requirements of industrial application of steel has good formability and corrosion resistance, following on from the small I came to tell you!

It is generally believed that improving the deep drawing properties of ferritic stainless steels is mainly to reduce the content of interstitial elements (C and N), to improve crystallographic orientation and to develop texture structures. Reduce the gap elements (C, N) content by Nb, Ti dual stabilization, development organization depends on the texture of cold rolling and annealing, the annealing temperature is the main factor affecting the distribution of grain size and grain size of different texture, at different annealing temperatures and different types of texture of grain size distribution large.

Therefore, it is important to study the influence of annealing temperature on the microstructure and properties of 00Cr12TiNb ferritic stainless steel. In this paper, ferritic stainless steel as the research object, to study the annealing process of 00Cr12TiNb ferritic stainless steel body and properties of tissue by using metallographic microscope, SEM and mechanical property test, to provide the reference for the optimization of process parameters in practical production.

The experimental materials are ingots made by hand arc furnace smelting, and the main components (mass fraction,%) are: 0.01C, 0.41Si, 0.25Mn, 0.027P, 0.005S, 11.32Cr, 0.50Nb, 0.25Ti, 0.009N, Fe margin. The ingot is forged at room temperature, the initial forging temperature is 1050 degrees, the final forging temperature is 890 degrees, and the forging deformation amount is 60%. Then the steel plate is cut into 15mm * 10mm * 8mm sample and annealed by SX2-2.5-12 box type resistance furnace. In order to observe the grain growth process after recrystallization, the annealing process is: holding 3min at different temperatures (860, 890, 920, 950 and 980 DEG C), and air cooling.

When the stainless steel is annealed at 920 degrees, the reaction of the microstructure and recrystallization of the minor grains occur mainly. Recrystallization begins at 920, and the recrystallized structure reaches the optimum at 950 DEG C, and the recrystallized grains are obviously coarser at 980. During annealing, the NbTi (C, N) diffused in the intragranular and grain boundaries of ferritic stainless steel. With the increase of annealing temperature, the precipitation of NbTi (C, N) increased obviously, and when the annealing temperature reached 950, the amount of precipitation was the highest.

The precipitation of NbTi (C, N) can improve the strength and toughness of 00Cr12TiNb ferritic stainless steel. Under annealing temperature, the yield strength of the sample decreases obviously, and the hardness decreases slightly. At the recrystallization temperature above the annealing temperature, the yield strength of the sample increases and the hardness tends to be stable.