固溶处理对低镍双相不锈钢耐点蚀及强韧性能的影响

Effect of Solid Solution Treatment on Pitting Corrosion and Strength-Toughness Properties of Low-Nickel Duplex Stainless Steel

摘要:

采用“C/N+Mn代Ni”的合金设计方法,制备出了一种具有良好热加工性能的低镍双相不锈钢21Cr-DSS,并研究了固溶处理工艺对新钢种微观组织、强韧性及耐点蚀性能的影响。结果表明：21Cr-DSS在热轧过程中铁素体比奥氏体更容易发生动态软化。固溶温度比保温时间对21Cr-DSS中两相比例的影响更明显,且奥氏体晶粒尺寸稳定性优于铁素体。随固溶温度升高,21Cr-DSS的强韧性得到改善,但当温度超过1100°C后,强韧性下降。在1050°C固溶处理30min时,21Cr-DSS具有最佳的综合性能,此时强塑积为58.9GPa%,-40°C低温冲击功为84J,在3.5%氯化钠溶液中的点蚀电位为0.43V。21Cr-DSS比常规LDX2101具有更优异的热加工性能和强韧性,且耐点蚀性能基本相当。与AISI 304奥氏体不锈钢相比,21Cr-DSS的强度和耐点蚀性能明显更优。

Abstract:

A novel low-nickel duplex stainless steel of 21Cr-DSS with excellent hot workability was prepared by the alloying design of "C/N+Mn instead of Ni", while the effects of solid solution treatment on its microstructure, strength-toughness and pitting corrosion resistance were studied. The ferrite of 21Cr-DSS during hot-rolling was more susceptible to dynamic softening than austenite. The effect of solid solution treatment temperature on the ferrite/austenite ratio in 21Cr-DSS was more obvious than that of holding time, and the stability of austenite grain size was better than that of ferrite. The strength and toughness of 21Cr-DSS were improved with an increase in solid solution temperature, but when the temperature exceeded 1100°C, its strength and toughness were decreased. The 21Cr-DSS solid solution treated at 1050 °C for 30min had the excellent comprehensive properties, with the PSE (product of strength and plasticity), -40°C impact energy and pitting potential in 3.5% sodium chloride solution having been measured to be about 58.9GPa%, 84J and 0.43V, respectively. The 21Cr-DSS has the more excellent hot workability and strength-toughness than LDX2101, and the similar pitting corrosion resistance. Compared with AISI 304 austenitic stainless steel, the 21Cr-DSS has the higher strength and pitting corrosion resistance.