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1、 VALBRUNA NORDIC AB EN 1.4539 0509 ENG 1. High alloy Austenitic Stainless Steel EN 1.4539 UNS N08904 904L A stainless austenitic steel Typical analysis % C Cr Ni Mo Others EN 1.4539 0,02 20 25 4,2 Cu Delivery condition Solution annealed (EN 1.4539 replaces SS 2562 27) Characteristic temperatures Tem
2、peratureC Solidification range Scaling temperature in air 1390-1315 1000 Hot forming Solution annealing Stress relief annealing (max 5h) 1200-900 1050-1150 500 Use in pressure vessels (-60)-400 Mechanical properties Values for solution annealed condition acc. to EN 10272 Tensile strength Rm N/mm2530
3、-730 Proof strength Rp0,2 N/mm2Min 230 Proof strength Rp1,0 N/mm2Min 260 Elongation A5 % Min 35 (30) Impact energy KV 20C J/cm2 Min 100 (60) Hardness HB Max 230 ( ) 160d250 Physical properties Temperature C 20 100 200 300 400 Density kg/dm3 8,0 - - - - Modulus of elasticity E kN/mm2 195 190 180 172
4、165 Mean coeff. of therm.expansion 20C Temp. 10-6 K-1 - 15 15,5 16 16 SpecificTherm. Capacity W/m C 13 13,5 14 15 16 Electrical Resistivity m 0,85 - - - - Specific heat J/kg C 500 - - - - EN 1.4539 904L is a high alloy austenitic stainless steel with low carbon content. The grade is intended for use
5、 under severe corrosive conditions. The steel grade was originally developed to resist corrosion in dilute sulphuric acid. EN 1.4539 is fully austenitic, and is less sensitive to precipitation of ferrite and sigma phase than conventional austenitic grades with high molybdenum content. Due to the com
6、bination of relatively high contents of chromium, nickel, molybdenum and copper, EN 1.4539 has good resistance to general corrosion, particulary in dilute sulphuric acid. It is non-magnetic in the annealed condition but may become slightly magnetic as a result of cold- working or welding. Design fea
7、tures Good resistance to uniform corrosion Good resistance to pitting and crevice corrosion Very good resistance to stress corrosion cracking Good resistance to intercrystalline corrosion Good formability and weldability Corrosion resistance Uniform corrosion Uniform corrosion is characterized by a
8、uniform corrosion of the steel surface in contact with the corrosive medium. Resistance is normally considered good if the corrosion rate is less than 0,1 mm/year. As a result of its high chromium, nickel and molybdenum contents and its alloying with copper, EN 1.4539 is passivated even in reducing
9、environments such as dilute sulphuric acid and formic acid. Its high nickel content contributes towards its relatively low corrosion rate in the active state. Intercrystalline corrosion EN 1.4539 has a very low carbon content. This means that there is very little risk of carbide precipitation in con
10、nection with ordinary heat treatment and welding. The risk of intercrystalline corrosion after ordinary heat treatment and welding is thereby eliminated. Stress corrosion cracking Conventional steels of the 1.4301 and 1.4401 type are sensitive to stress corrosion cracking (SCC) under certain conditi
11、ons, i.e. a special environment in combination with tensile stress in the material, and often also an elevated temperature. Resistance to SCC increases with the increased content of nickel and molybdenum. Owing to its high nickel and molybdenum contents EN 1.4539 is highly resistant to stress corros
12、ion cracking in chloride solutions, concentrated hydroxide solutions and environments rich in hydrogen sulphide. Pitting and crevice corrosion Resistance to pitting corrosion and crevice corrosion is determined mainly by the content of chromium, molybdenum and nitrogen in the material. This is often
13、 illustrated by using the pitting resistance equivalent (PRE) for the material, which can be calculated using the formula: PRE = %Cr + 3.3 x %Mo + 16 x %N Heat treatment Solution annealing 1050-1150 C. Holding time at solution annealing temperature approx. 30 min, followed by rapid cooling in air or
14、 water. Hardening This grade cannot be hardened by heat treatment, but it can be hardened by cold working. Fabrication Hot and cold forming Hot forming should be carried out in the temperature range 1200-950C. It is important that the entire workpiece has been exposed to a sufficiently high temperat
15、ure. In the case of partial heating, or cooling that is too slow, hot working should be followed by solution annealing. Bending, pressing and other forming operations can easily be done in cold condition. As with other austenitic steels, intermediate annealing must be carried out in connection with
16、the more complicated forming operations such as complex deep drawing. Machining Like other austenitic steels EN 1.4539 is tough and has a tendency towards work-hardening. This must be taken into account when the grade is machined. With the right choice of tool and machine data, fully satisfactory machining results can be obtained with this grade. For mo
