904L供货规格： 
圆钢、棒材、带材、管材、阀座、球体、法兰和锻件协商供应

化学成分：

物理性能：

904L在常温下合金的机械性能的最小值：

特性： 
904L是一种含炭量很低的高合金化的奥氏体不锈钢。该钢是为腐蚀条件苛刻的环境所设计的。最初该合金是为在稀硫酸中抗腐蚀而开发的。这一特性经多年的实际应用已被验证是很成功的。现在904L在许多国家中已被标准化，且已被审定可有于制造压力容器。904L合金与其他常用的CrNi奥氏体钢一样，具有良好的抗点腐蚀和缝隙腐蚀的能力、很高的抗应力腐蚀破裂的能力、良好的抗晶间腐蚀能力、良好的可加工性和可焊性。热锻时最高加热温度可达1180摄氏度，最低停锻温度不小于900摄氏度。此钢热成型可在1000--1150摄氏度进行。该钢的热处理工艺为1100--1150摄氏度，加热后快冷。此钢虽可采用通用的焊接工艺进行焊接，但是最恰当的焊接方法是手工电弧焊和钨极氩弧焊。当采用手工电弧焊焊接不大于6毫米板材时焊条直径不大于2.5毫米；当板厚大于6毫米时焊条直径小于3.2毫米。当焊后需热处理时，可以在1075--1125摄氏度加热后快冷进行处理。用钨极氩弧焊焊接时的填充金属可用同材焊条，焊后焊缝须经酸洗，钝化处理。

金相结构： 
904L是完全奥氏体组织，舆一般含钼量高的奥氏体不锈钢相比，904L对铁素体和α相的析出不敏感。

耐腐蚀性： 
由于904L碳含量是很低的（最大0.020%），因此在一般热处理和焊接的情况下，不会有碳化物析出。这样消除了一般热处理和焊接后出现在的晶间腐蚀的危险。由于高的铬镍钼含量，并且添加了铜元素，因此904L即使在还原性环境中，如硫酸和甲酸中也可以被钝化。高的镍含量使其在活性状态下也有较低的腐蚀速度。在0~98%的浓度范围内纯硫酸中，904L的使用温度可高达40摄氏度。在0~85%浓度范围内的纯磷酸中，其抗腐蚀性能是非常好的。在湿法工艺生产的工业磷酸中，杂质对抗腐蚀性能有很强的影响。在所有各种磷酸中，904L抗腐蚀性优于普通的不锈钢。在强氧化性的硝酸中，904L与不含钼的高合金化的钢种相比，抗腐蚀性能较低。在盐酸中，904L的使用仅限于较低的浓度1-2%。在这个浓度范围。904L的抗腐蚀性能好于常规不锈钢。904L钢具有很高的抗点腐蚀能力。在氯化物溶液中其抗缝隙腐蚀能力也是很好的。904L的高镍含量，降低了在麻坑和缝隙处的腐蚀速度。普通的奥氏体不锈钢在温度高于60摄氏度时，在一个富氯化物的环境中对应力腐蚀可能是敏感的，通过提高不锈钢的镍含量，可以降低这种敏化性。由于高的镍含量，904L在氯化物溶液，浓缩的氢氧化物溶液和富硫化氢的环境中，具有很高的抗应力腐蚀破裂能力。

904L应用范围应用领域有： 
904L合金是一种多用途的材料，在许多工业领域都能应用：
1.石油、石化设备，如石化设备中的反应器等。
2.硫酸的储存与运输设备，如热交换器等。
3.发电厂烟气脱硫装置，主要使用部位有：吸收塔的塔体、烟道、档门板、内件、喷淋系统等。
4.有机酸处理系统中的洗涤器和风扇。

Austenitic stainless steel

904L domestic and foreign corresponding number:

The United States

UNS Germany

The SEW VDIUV

904 l N08904 W.N r. 1.4539

904L supply specifications:

The round steel, rod, strip, pipe, seat, ball, flange and forgings negotiate supply

Chemical composition:

Alloy C Mn Si P S Cr Ni Mo Cu Fe other

904 l acuities were 0.02, 2.0, 1.0, 0.30, 0.020 or less or less or less or less 24 ~ 26 4.0 ~ 5.0 4.0 19.0 ~ 21.0 ~ 2.0 acuity 49.0 N 49.0 ~ 49.0

Physical performance:

The density of 8.0 g/cm3

Melting point of 1300-1390 ℃

The minimum mechanical properties of 904L alloy at normal temperature:

Tensile strength of alloy

Rm N/mm2 yield strength

RP0.2 N/was elongation

A5 %

904 l 490 490 35

Features:

904L is a highly alloyed austenitic stainless steel with low carbon content. The steel is designed for harsh conditions of corrosion. Initially the alloy was developed for corrosion resistance in dilute sulphuric acid. This feature has been proven to be successful over the years. Now 904L has been standardized in many countries and has been approved for manufacturing pressure vessels. 904 l alloy and other commonly used CrNi austenitic steel has good resistance to pitting corrosion and crevice corrosion ability, high resistance to stress corrosion cracking ability, good ability of intergranular corrosion resistance, good weldability and workability. The maximum heating temperature can reach 1180 degrees centigrade, and the minimum stop forging temperature is not less than 900 degrees centigrade. This steel thermal molding can be made at 1000-1150 c. The heat treatment process for the steel is 1100--1150 degrees Celsius, and the heat is quickly cooled. This steel can be welded with general welding process, but the most suitable welding method is manual arc welding and tungsten electrode argon arc welding. The diameter of the electrode is not greater than 2.5mm when the manual electric arc welding is not greater than 6mm. The electrode diameter is less than 3.2mm when the thickness of the plate is greater than 6mm. When heat treatment is required after welding, it can be processed at 1075-1125 degrees Celsius. The filler metal used in welding with tungsten electrode is used for welding rod. After welding, the weld must be pickling and passivating.

Metallographic structure:

904L is completely austenitic tissue. Compared with the austenitic stainless steel with high molybdenum content, 904L is not sensitive to the precipitation of ferrite and alpha phase.

Corrosion resistance:

Because of the low carbon content of 904L (0.020%), there is no carbon precipitation in general heat treatment and welding. This eliminates the risk of the corrosion of the crystals that occur after the general heat treatment and welding. Because of the high chromium nickel molybdenum content and the addition of copper, 904L can be passivated even in reductive environments such as sulfuric acid and formic acid. The high nickel content also has a low corrosion speed in the active state. In pure sulfuric acid of 0~98% concentration, the temperature of 904L can be as high as 40c. The corrosion resistance of pure phosphoric acid in the concentration range of 0~85% is very good. In industrial phosphoric acid produced by wet process, impurity has a strong influence on corrosion resistance. Of all kinds of phosphoric acid, 904L is better than normal stainless steel. In the highly oxidized nitric acid, 904L is less resistant to corrosion than the high-alloyed steel without molybdenum. In hydrochloric acid, the use of 904L is limited to a low concentration of 1-2%. In this concentration range. The corrosion resistance of 904L is better than conventional stainless steel. 904L steel has high resistance to point corrosion. It is also very good to resist crack corrosion in chloride solution. The high nickel content of 904L reduces the corrosion rate of the pits and cracks. Ordinary austenitic stainless steel when temperature is higher than 60 degrees Celsius, in a rich chloride environment sensitive to stress corrosion may be, by improving the nickel content of stainless steel, can reduce the sensitization. Due to high nickel content, 904L is highly resistant to stress corrosion cracking in the environment of chloride solution, concentrated hydroxide solution and hydrogen sulfide.

The application range of 904L is:

The 904L alloy is a versatile material that can be used in many industrial fields:

1. Petroleum and petrochemical equipment, such as reactor in petrochemical equipment.

2. The storage and transportation equipment of sulfuric acid, such as heat exchanger.

3. The flue gas desulfurization device of power plant is mainly used in the main parts: tower body, flue, damper, inner parts, sprinkler system etc.

4. The scrubber and fan in the organic acid treatment system.