申博体育开户 - 申博体育网站

申博体育开户 - 申博体育网站

 

Super austenitic stainless steel

Semeier Steel Company alloy 904L stainless steel plate thickness in 3/16 "to 2"。The alloy (Super austenitic stainless steel 904L UNS N08904) is designed for corrosion and pitting in a wide range of processing environments。It is widely used in the chemical process industry, including the production of phosphate fertilizers。

Alloy 904L available thickness:

3/16" 1/4" 3/8" 1/2" 5/8" 3/4"
4.8mm 6.3mm 9.5mm 12.7mm 15.9mm 19mm
 
1" 1 1/4" 1 1/2" 1 3/4" 2"
25.4mm 31.8mm 38.1mm 44.5mm 50.8mm

一般

904L alloy is a super austenitic stainless steel designed for a variety of medium and high corrosion resistance environments。The high content of chromium and nickel, combined with molybdenum and copper, ensures excellent corrosion resistance。

Take 25% nickel with 4.With high alloying chemical composition of 5% molybdenum, 904L is superior to 316L and 317L in chloride stress corrosion cracking, pitting and corrosion resistance。

904L alloy was originally developed for corrosion resistance in dilute sulfuric acid。It also has good corrosion resistance to other inorganic acids (such as hot phosphoric acid) and most organic acids。

904L alloy is easily welded and machined in standard shop manufacturing practice。


应用

  • Control air pollution - scrubbers used in coal-fired power plants
  • Chemical processing - processing equipment for the production of sulfuric, phosphoric, inorganic and organic acids and phosphate fertilizers
  • Metallurgical processing - pickling equipment using sulfuric acid
  • Oil and gas production -- offshore processing equipment
  • Pharmaceutical industry -- processing equipment
  • Pulp and paper - processing equipment
  • Sea and brackish water -- condensers, heat exchangers and piping systems

标准

ASTM........A 240, B 625
ASME........SA 240, SB 625

The corrosion resistance

904L alloy has excellent uniform corrosion resistance due to its high alloy content。

904L alloy was originally developed for corrosion resistance in dilute sulfuric acid, and is one of the few stainless steels that can maintain complete corrosion resistance at temperatures up to 95°F (35°C) in the entire concentration range from 0 to 100%。904L also has good corrosion resistance against many inorganic acids (such as phosphoric acid) and most organic acids。However, acids and acid solutions containing halogen ions are highly corrosive, and 317L, 317LMN, and 904L resistance may not be sufficient。

Fractionated tol usually requires a material superior to 316L and the more commonly used 317MN。In these hot concentrated alkaline solutions, the corrosion resistance of materials is mainly determined by their nickel content。With a nickel content of up to 25%, 904L has proven to be an excellent alternative to most conventional stainless steels。

Conventional stainless steel 304L and 316L are susceptible to chloride stress corrosion cracking under certain conditions。The tolerance of chloride stress corrosion cracking increases with the increase of nickel and molybdenum content。Therefore, higher performance super austenitic stainless steels such as 904L have higher chloride stress corrosion cracking tolerance。The table in the upper right shows the chloride stress corrosion cracking tolerance of different alloys in the presence of evaporation of chloride ion solution。Super austenitic stainless steel and duplex stainless steel are significantly superior to 316L。

Corrosion Resistance

Corrosion Resistance

Uniformly corroded in pickling acid at 25°C

牌号 Corrosion rate (mm/year)
316L >6
904L 0.47
254 SMO ® 0.27
654 SMO ® 0.06

* Composition: 20% HNO3 + 4 HF.

Uniformly corroded in wet-process phosphoric acid at 60°C

牌号 Corrosion rate (mm/year)
316L >5
904L 1.2
254 SMO ® 0.05

Composition: 54% P2O5, 0.06% HCI, 1.% 1% HF, 4, 0 H2SO4, 0.27% Fe2O3, 0.17% AI2O3, 0.10% SiO2, 0.20% CaO and 0.70% MgO.

Corrosion rates in the fatty acid environment at 253°C for distillation of Tall oil

牌号 Corrosion rate (mm/year)
316L 0.88
317LMN 0.29
904L 0.056
254 SMO ® 0.01

Chemical analysis

Specific Gravity % (all values are maximum unless otherwise specified)

23.0 min.-28.0 max. 1.00
19.0 min.-23.0 max. 0.045
4.0 min.-5.0 max. 0.035
1.0-2.0 max. Balance
2.00

Physical properties

密度

0.287 lbs/in3
7.95 g/cm3

比热

0.11 BTU/ LB -°F (32 -- 212°F)
450 J/kg-°K (0-100°C)

Modulus of elasticity

28.0 x 106 psi
190 GPa

 

Thermal conductivity 212°F (100°C)

6.8 BTU/Ft - hr ° F
12.9 W/m - ° K

Melting point range

2372 – 2534°F
1300 – 1390°C

The resistivity

33.5 Microhm - in at 68 ° C
95.2 Microhm - cm at 20 ° C

Expansion coefficient

Temperature range  
°F °C In/in ° F Cm/cm ° C
68-212 20-100 8.5 x 10-6 15.3 x 10-6

Mechanical properties of

Typical values for 68°F (20°C) (all values are minima unless otherwise noted)

The yield strength
0.2% Offset
The ultimate
Tensile strength
elongation
Within 2 inches
硬度
psi (min.) (MPa) psi (min.) (MPa) % (min.) (max.)
31,000 220 71,000 490 36 70-90 Rockwell B

Manufacturing data

 

904L alloy is easily welded and machined in standard shop manufacturing practice。

Cold forming

904L is easy to stretch and shape。The increased molybdenum and nitrogen compared to the 304 or 304L standard means that it requires more powerful processing equipment。

Hot forming

Recommended operating temperatures for hot working processes are 1562-2102°F (850-1150°C)。The usual next steps for hot working are annealing and quenching, but for 904L, if the hot forming is stopped at temperatures above 2012°F (1100°C), the material is directly hardened, so the material can be used without subsequent heat treatment。Importantly, the entire workpiece can be hardened at temperatures higher than 2012°F (1100°C)。When local heating or cooling is below 2012°F (1100°C), hot working should always follow the subsequent operations of annealing and quenching if cooling has been too slow。The 904L shall be annealed at the temperature range 1940 -- 2084°F (1060 -- 1140°C)。

加工

The cold work hardening rate of 904L alloy makes it less workable than 410 and 304 stainless steel

焊接

904L alloy can be welded in most standard machining。The austenitic plate material has uniform austenite structure and uniform distribution of alloying elements。Solidification after welding causes redistribution of certain elements such as molybdenum, chromium and nickel。These retained elements in the welded casting tissue separate and can impair corrosion resistance in some environments。Element separation is not obvious in 904L, and the material is usually welded with filler metal of the same composition as the base metal, or can be welded without filler metal。

The welding material for 904L is 20 25 CuL electrode and 20 25 CuL wire。

LDX 2101 and 254 SMO are registered trademarks of Otokhump Stainless Steel, Inc.

The information and data provided in this product data sheet are the most accurate information we have at present。This data is for reference only and subject to change without prior notice。The description of the areas of application of the materials is intended only to assist the reader in making his or her own evaluation and decision and is not guaranteed or deemed to be an express or implied guarantee of continued applicability in those areas of application。

Association and Certification