New Economical 19Cr Duplex Stainless Steels
- PDF / 927,172 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 87 Downloads / 221 Views
INTRODUCTION
AUSTENITIC stainless steels are attractive as structural materials in automobile and transportation industries because of their good toughness and formability. A typical representative of the austenitic stainless steel is AISI 304, but it has a high cost due to the high Ni content (8 wt pct). For that reason, cost-efficient duplex stainless steels (DSSs) with high mechanical properties and corrosion resistance are being actively developed by replacing expensive Ni with cheap Mn and N.[1,2] Although it is not believed to be as effective as nickel, the austenite-stabilizer Mn is 7 to 8 times cheaper than Ni at an equivalent weight and helps improve nitrogen solubility, while the austenite-stabilizer nitrogen has an austenite-stabilizing effect equivalent to 30 times that of Ni and therefore can be used to replace the expensive Ni. What is more, nitrogen can also increase the strength and retard the sensitization. The chromium and molybdenum elements are essential for the improvement of pitting corrosion resistance, but their contents are restricted to a certain level to avoid the formation of harmful intermetallic phases, such as r, v, etc.[3,4] So far, some DSSs with free- and low-nickel levels have been reported. Wang et al.[5] investigated microstructure and property of a type of nickel-free DSS Fe-22Cr-10Mn0.35N and found that the steel had high strength and toughness, good corrosion resistance, and low alloy JUN LI, Postdoctoral Student, ZIXING ZHANG and HONG CHEN, Masters, and XUESHAN XIAO, Professor, are with the Institute of Materials, Shanghai University, 200072, Shanghai, P.R. China. Contact e-mail: [email protected] JUNLIANG ZHAO and LAIZHU JIANG, Senior Engineers, are with Baoshan Iron & Steel Co., Ltd., Shanghai 200431, P.R. China. Manuscript submitted August 7, 2010. Article published online October 15, 2011 428—VOLUME 43A, FEBRUARY 2012
element cost. Toor et al.[6] developed a high Mn and Ni-free DSS containing 18Cr-6Mn-1Mo-0.2N, which could be used for load frame materials in automobiles. A recently developed low alloyed (lean) LDX 2101 DSS with low addition of nickel was reported to have high fracture toughness for both base and weld materials.[7] The authors previously developed a 25Cr-2Ni-3Mo10Mn-0.5N economical duplex alloy and studied the effect of Mn and N on the microstructure, mechanical properties, and corrosion resistance of the steel, whose mechanical properties and corrosion resistance were better than those of SAF2507.[8] For DSS, excellent corrosion resistance, particularly the localized corrosion resistance, arises mainly from its duplex microstructure, which means one phase could be cathodically protected by the other, and the presence of several key alloying elements, which primarily contain Cr, Mo, and N. Meanwhile, the elements of W and Cu are also reported to have positive effects in corrosion resistance. The addition of W not only increases localized corrosion resistance, but also significantly delays the precipitation rate of r phase.[9,10] The addition of copper in s
Data Loading...
