IDEA #4UN0BI New High-Strength, Corrosion Resistance And Weldable Al Based Alloy Compositions

APPLIED RESEARCH • NEWMATERIALS RESEARCH NEW HIGH(cid:2)(cid:2)STRENGTH,, CORROSION RESISTANCE AND WELDABLE AALL BASED ALLOY COMPOSITIONS Description A new rapid technology based on the use of modified water atomization (see Fig. 1) followed by direct powder extrusion has been developed. The atomisation stage is innovative and realised as a pilot plant. The pilot plan built provides: (a) cool(cid:2) ing rates between 5x104 and 106 K/s, (b) 2 to 10 kg of pow(cid:2) der per atomisation run, (c) minus 40μ size fraction amounts to 70% at water pressure of 150 atm, (d) low surface oxidation, and (e) powders being highly irregular in shape are easy to press. New high(cid:2)strength, corrosion resistant weldable Al based alloy compositions have been developed, produced by the pro(cid:2) posed technology in the form of strips (Fig. 2) and tested (Table below) Properties Room temperature strength, MPa Elongation, % Weldability High strength 7xxx alloys 500(cid:2)550 8(cid:2)12 Weldable Strength of weldments, MPa 300(cid:2)350 Stress corrosion cracking, MPa 270(cid:2)350 Low frequency fatigue strength, cycles/Load Fracture toughness, K1c, MPa m1/2 40(cid:2)65 8x104(cid:2)6x105/ 160 MPa Ultra(cid:2)high strength 7xxx alloys 550(cid:2)650 7(cid:2)9 Welded by resistance welding 270(cid:2)310 100(cid:2)150 8x104/160 MPa 25(cid:2)30 Developed alloys 620(cid:2)670 8(cid:2)12 Very easy to weld 530(cid:2)570 300(cid:2)350 8x104/160 MPa 60(cid:2)65 Innovative Aspect and Main Advantages:: The main advantages of the proposed technology over the existing prototypes (gas atomisation and centrifugal atomisa(cid:2) tion): (1) explosion and fire(cid:2)proof, (2) environmental safety (dust(cid:2)free process), (3) higher productivity in powder produc(cid:2) tion, (4) higher economical efficiency, and (5) recycling of wastes of packaging aluminium. The principal advantage of the developed alloys over the exist(cid:2) ing commercial materials consists in a unique combination of different properties. The tensile and yield strength of new alloys are similar to those of high strength commercial 7075 alloy while their stress corrosion cracking and fracture tough(cid:2) 18 ness are similar to the characteristics of less strength materi(cid:2) als, such as 1973, 1949 etc alloys. Areas ooff Application:: Production of alloys for transport (aircraft and shipbuilding industry) and consumer goods (wheelchairs and sportive goods) Stage ooff Development:: • Patented in Russia and Ukraine (2 Ukrainian and 2 Russian patents) • Pilot plant is operative • New Al alloys are produced, tested and available for demonstration Contact Details:: Frantsevych Institute for Problems of Materials Science, Krzhizhanivsky St. 3, Kiev, 03142, Ukraine Contact Person: Alexander Krajnikov Tel: 380–44–4240294 Fax: 380–44–4242131 Email: avk@materials.kiev.ua