30cr13 martensitic stainless steel has good mechanical properties, hardenability and corrosion resistance, which is widely used in medical devices, measuring instruments and molds. The low temperature toughness and strength of 30cr13 steel can be significantly improved by the dispersion precipitation of carbon and nitride (size less than 5 nm) and the solid solution refining of Nb under the condition of low carbon equivalent. The low temperature toughness and strength of 30cr13 steel can be significantly improved, and the steel has good welding performance and service performance.
Mao honghuan et al. Found that the type and quantity of carbides have an important influence on the strength, hardness and corrosion resistance of 30cr13 steel. Tempering test shows that too much carbides will reduce the tensile strength of the steel and obviously deteriorate the corrosion resistance of the steel. It is found that the carbide content of the steel quenched from 1020 ℃ is lower than that of the steel quenched from other temperatures in the temperature range of 950-1050 ℃. For specific parts, quenching hardness has little effect on its service performance, and the influence of carbide content is more important. For example, Jin Yangfan found that the hardness of 30cr13nb0.1 martensitic stainless steel quenched at 1050 ℃ and tempered at 400 ℃ is lower than that quenched at 1020 ℃ due to excessive carbides. In the past, the effect of tempering process on precipitates and mechanical properties of Nb bearing martensitic stainless steel was less studied, but Trace Nb has great influence on carbide formation and mechanical properties of steel. It is worth studying whether 30cr13 steel can obtain more comprehensive properties, reduce production cost and improve product competitiveness by adding Nb and reasonable tempering treatment. The effect of tempering temperature on the microstructure and mechanical properties of 30cr13nb0.1 cast martensitic stainless steel was studied in order to provide a theoretical basis for further improving the properties of the material.
(1) the carbides in 30cr13nb0.1 martensitic stainless steel contain NB C besides M23C6. The carbides in the steel tempered at lower temperature are in the form of point and fine chain, while those tempered at higher temperature are in the form of long chain. With the increase of tempering temperature, the precipitation amount of M23C6 carbides first increases and then decreases, the precipitation amount of NBC increases all the time, and the total amount of the two carbides increases.
(2) tempering temperature significantly affects the mechanical properties of 30cr13nb0.1 steel. With the increase of tempering temperature, the hardness first decreases and then increases, and the impact toughness first increases and then decreases. The hardness of the steel tempered at 450 ℃ is the highest, and the impact toughness of the steel tempered at 350 ℃ is the best.
(3) the corrosion resistance of 30cr13nb0.1 steel tempered at 450 ℃ is the worst, and the pitting corrosion resistance of steel tempered at 350 ℃ is better than that tempered at 250 ℃.
(4) 30cr13nb0.1 cast martensitic stainless steel quenched at 1020 ℃ and tempered at 350 ℃ has better comprehensive properties.