摘要
A new series of economical Mo-free duplex stainless steels 21.5Cr-3.5Ni-xW-0. 2N （x = 1.8 -- 3. 0, mass%） have been developed. The effects of W on mechanical properties and corrosion resistance were investigated, and the microstructures were analyzed by optical microscopy, X-ray diffraction, transmission electron microscopy and electron backscatter diffraction. The designed steels have a balanced ferrite-austenite relation and are free of sigma phase after solution treatment at 750--1 300 ~C for 30 min followed by water-quenching, whereas a small number of Cr23 C~ precipitates were found after solution treatment at 750 ~C. After solution treatment at 1050 ℃, the steel with 1.8~ （mass percent） W exhibits the highest room temperature tensile strength due to the strongest work hardening effect, while the steel with 3.0% （mass percent） W exhibits the highest fracture elongation owing to the transformation-in- duced plasticity （TRIP） effect. The ductile-brittle transition （DBT） and martensite transformation are respectively found in the ferrite and austenite, which deteriorates the impact properties of the steels with the increase of W con- tent. The corrosion resistance of the designed steels is improved with the increase of W content. The pitting resistance of austenite is obviously better than that of ferrite for the designed alloys. Among the designed steels, the steel with 1.8% （mass percent） W is found to be an optimum steel with excellent comprehensive properties and lowest production cost.
A new series of economical Mo-free duplex stainless steels 21.5Cr-3.5Ni-xW-0. 2N （x = 1.8 -- 3. 0, mass%） have been developed. The effects of W on mechanical properties and corrosion resistance were investigated, and the microstructures were analyzed by optical microscopy, X-ray diffraction, transmission electron microscopy and electron backscatter diffraction. The designed steels have a balanced ferrite-austenite relation and are free of sigma phase after solution treatment at 750--1 300 ~C for 30 min followed by water-quenching, whereas a small number of Cr23 C~ precipitates were found after solution treatment at 750 ~C. After solution treatment at 1050 ℃, the steel with 1.8~ （mass percent） W exhibits the highest room temperature tensile strength due to the strongest work hardening effect, while the steel with 3.0% （mass percent） W exhibits the highest fracture elongation owing to the transformation-in- duced plasticity （TRIP） effect. The ductile-brittle transition （DBT） and martensite transformation are respectively found in the ferrite and austenite, which deteriorates the impact properties of the steels with the increase of W con- tent. The corrosion resistance of the designed steels is improved with the increase of W content. The pitting resistance of austenite is obviously better than that of ferrite for the designed alloys. Among the designed steels, the steel with 1.8% （mass percent） W is found to be an optimum steel with excellent comprehensive properties and lowest production cost.
基金
Item Sponsored by National Key Technology Research and Development Program in 12th Five-Year Plan of China(2012BAE04B02)
Innovation Fund of Education Commission of Shanghai Municipality of China(12CXY10)
