904L ,super austenitic stainless steel ,belongs to low carbon high
nickel and molybdenum austenitic stainless acid-resistant steel, is
proprietary material introduced from the h. S company of French. 904L has the very good
activation - passivation shift ability, excellent corrosion
resistance, in the oxidizing acid such as sulfuric acid, acetic
acid, formic acid, phosphoric acid have good corrosion resistance,
in the neutral medium containing chloride ions has the very good
resistance to pitting corrosion, and has a good resistance crevice
corrosion and stress corrosion resistance. Applicable to various
concentrations of sulphuric acid under 70 ℃, under ordinary
conditions of pressure resistance to any concentration, temperature
of acetic acid and formic acid and acetic acid in mixed acid
corrosion resistance is very good also.
Grades In Different Standard：
904L austenitic organization is completely, and compare with
generally high molybdenum austenitic stainless steel ,904 l is not
sensitive to ferrite and the precipitation ofαphase.
Density：8.0g/cm3。Tensile Strength：σb≥520Mpa。Elongation Rate：δ≥35%。
Corrosion Resistance :
Since the 904L carbon content is very low (Max:0.020%), so in the
case of the general heat treatment and welding, there would be no
carbide precipitation. It eliminated the the risk of intergranular
corrosion after general heat treatment and welding . Because of the
high content of nickel ,chrome, molybdenum , and add the copper
element, so ,904L even in a reducing environment, such as sulfuric
acid and formic acid , it can also be blunted.High nickel content
in the active state has low corrosion rate.In the concentration range of 0 ~ 98% pure sulfuric acid, the Celsius temperature of use 904L can be as high as 40 degrees
. In 0 ~ 85% concentration range of pure phosphoric acid , its
corrosion resistance is very good. In the industrial phosphoric
acid production of wet process, impurities has a strong influence
to against corrosion . In all various kinds of phosphate, 904L
stainless steel corrosion resistance is superior to the ordinary.
904L, in strong oxidizing nitrate, compared with the high alloying
steel does not contain molybdenum, has low corrosion resistance. In
hydrochloric acid, the use of 904L is limited to low concentration
of 1-2%. In this concentration range,904L has a good corrosion resistance performance compare with the conventional
stainless steel .904L stainless steel has high corrosion
resistance. The crevice corrosion resistance in chloride solution
is also very good. High nickel content of 904L, reduced the hemp
pit corrosion speed and aperture place. Common austenitic stainless
steel ,when the temperature is higher than 60 degrees , in a rich
of stress corrosion in chloride environment is likely to be
sensitive.By raising the nickel content of stainless steel, can
reduce the sensitization. Because of the high nickel content ,904L
in chloride solution, concentration of hydroxide solution and rich
hydrogen sulfide environment, has the very high resistance to
stress corrosion cracking .
Welding materials：Welding rod（E385-16/17），Solder wire（ER385）。
*Petroleum, petrochemical equipment, such as petrochemical equipment
in the reactor.
*Sulfuric acid storage and transportation equipment, such as heat
*With power plant flue gas desulfurization device, main parts are:
absorption tower of the tower body, the flue, shift door plank,
internal parts, spray system, etc.
*Organic acid scrubber and the fan in the handle system.
*Water treatment plant, water heat exchanger, papermaking equipment,
sulfuric acid, nitric acid, sulphuric acid, pharmaceutical industry
and other chemical equipment, pressure vessels, food equipment.
*Pharmaceutical factory, centrifuge, reactor, etc.
*Plant foods: soy sauce pot, cooking wine, salt, and dressing
*To dilute sulphuric acid is strong corrosive medium is matching
with 904 l steel grade.
1.1 Welding Property
As with normal stainless steel, all kinds of welding methods may be
used for 904L. The most commonly used welding methods are manual
arc welding and inert gas protection welding, welding rod and wire
metal based on the parent metal composition and purity is higher,
the content of molybdenum demand is higher than the parent metal.
Generally do not need to preheat before welding, but working in the
cold outdoors, to avoid moisture agglutination, sub area or the
adjacent area need uniform heating.Pay attention to the local
temperature not more than 10 0 ℃, lest cause carbon concentration,
lead to intergranular corrosion. Welding need use small line
energy, continuous and fast welding speed. Generally do not need to
heat treatment after welding, in case need to heat treatment, must
rapidly cooling after heating to 110 ~ 110 ℃.
1.2 Machining Properties
Machining characteristics of 90 L austenitic stainless steel,
similar to other machining process has a tendency to stick knife
and work hardening. Carbide cutting tools, must adopt positive rake
Angle to sulfide and chlorinated oil as cutting coolant, equipment
and processes should be in order to reduce work hardening. Cutting
should avoid using slow speed and feed quantity in the process of
Mechanical Property In Normal Temperature: