Corrosion Resistance Copper Based Alloys Ni68Cu28Fe Monel400 N04400
For Pump / Valve
Monel400 is the corrosion-resistant alloy with the largest amount, the most
versatile and excellent comprehensive performance. The alloy has
excellent corrosion resistance in hydrofluoric acid and fluorine
gas media, and excellent corrosion resistance to hot concentrated
alkali liquor. It is also resistant to corrosion by neutral
solutions, water, sea water, atmosphere, organic compounds, etc. An
important feature of this alloy is that stress corrosion cracking
is generally not produced and the cutting performance is good.
Monel 400 Chemical composition
Monel 400 Physical properties
|Melting point||1300-1390 °C|
Monel 400 Alloy minimum mechanical properties in the room
R P0. 2 N/mm²
A 5 %
|Monel Spring wire||0.08mm-10mm|
|Monel plate||0.3mm-15mmX1000mmX L|
|Monel strip||0.06mm-2.0mmX 200mm X L|
|Monel Rod||8mm-40mm X L|
|Monel welding wire||1.2mm, 1.6mm, 2.0mm|
Characteristic as below
1.Monel 400 Metallurgical structure
2.Monel 400 alloy is high-intensity single-phase solid solution.
3, chloride ion stress corrosion cracking is very insensitive;
4. Excellent mechanical performance from below zero to 550℃;
5. It can be used as pressure vessel under -10~425℃ as approved by
6. Good machining and welding performance
7.Good corrosion resistance in Marine and chemical environment;
Gas Corrosion:Monel 400 alloys have excellent corrosion resistance
in fluorine, hydrochloric acid, sulfuric acid, hydrofluoric acid
and their derivatives. At the same time, it is more resistant to
corrosion in seawater than copper-based alloys.
Acid medium: Monel 400 is corrosion resistant in sulfuric acid with
a concentration of less than 85%. Monel400 is one of the few
materials that are resistant to hydrofluoric acid.
Water corrosion: Monel400 alloy has excellent corrosion resistance
in most water corrosion conditions, and pitting corrosion and
stress corrosion are rarely found. The corrosion rate is less than
High temperature corrosion: The maximum temperature of Monel400
working continuously in air is generally around 600 °C. In high
temperature steam, the corrosion rate is less than 0.026 mm/a.
Ammonia: Due to its high nickel content, Monel400 alloy can
withstand corrosion under anhydrous ammonia and ammoniating
conditions below 585 °C.
Monel 400 Application field
Monel 400 alloy is a multi-purpose material in many industrial
1. Seamless water pipe in the power factory
2. Sea-water exchanger and evaporator
3. Sulfuric acid and hydrochloric acid environment
4. Crude distillation
5. Sea-water in the use of equipment and propeller shaft
6. Nuclear industry and used in the manufacture of uranium
enrichment isotope separation equipment
7. Manufacturing hydrochloric acid equipment used in the production
of pump and valve
Manufacturing and heat treatment
The monel 400 can be easily manufactured using traditional
It is important to ensure that the surface of the monel 400 is
clean before heat treatment. If there is S, p on the surface of the
monel 400 during the heating process. The properties of alloys are
likely to be weakened by contaminants such as pb or other
low-melting metals. The main sources of contamination are marker
marks, temperature indicating paint, grease and furnace gas.
The monel 400 can be hot-processed at 800~1200℃, but only slightly
forged at 925℃. Thermal bending can be performed between 1025 and
1200℃. In order to carry out thermal processing, the furnace heat
treatment is required, the furnace temperature should be first
heated to 1200℃, and then the monel 400 materials into the heating.
Materials should be heated according to a rule: 60 minutes per
100mm thick. As soon as the heating time arrives, the material
shall be taken out for hot processing immediately. If the material
temperature drops below the minimum hot processing temperature
during the hot processing, it shall be reheated.
Cold - processed monel 400 material must be annealed. Because it
has a slightly higher work hardening rate than carbon steel, the
forming equipment to make appropriate changes. Cold forming shall
be annealed between processes. Cold deformation is sometimes used
to improve mechanical properties. If the material is to be used in
an environment where stress corrosion cracking is likely to occur,
such as mercury, moist exposed hydrogen fluoride gas, it is
recommended to conduct stress reduction heat treatment.
Generally, the annealing temperature of monel 400 materials is
700~900℃, and the best effect is at 825℃. Fast air cooling after
treatment can obtain good corrosion resistance. Annealing
temperature and annealing time are directly related to the final
grain size of materials, so annealing parameters should be
carefully considered. And the sulfur content of the gas in the
annealing furnace must be low to avoid brittle materials. Stress
relief heat treatment is generally conducted at 300℃ for 1~3 hours.
For pipes, the stress relief heat treatment temperature is
generally controlled at 550~650℃. Cleaning of material surfaces
prior to any heat treatment must be considered.
The oxides and stains near the weld seams of monel 400 materials
are tighter than those of stainless steel materials, which can be
polished by grinding wheel or pre-treated in salt bath before
pickling in a mixture of nitric and hydrofluoric acids.
The monel 400 material shall be machined in annealed condition.
Cold forming and stress relief after the material is easier to
process, this kind of material processing hardening to have enough
understanding, for example: the surface cutting speed and carbon
steel is smaller, the tool to continue to run, in order to avoid
the surface hardening layer, the amount of feed to large. Machining
tools should be nickel base alloy and high alloy stainless steel
special tools, brush weld to use stainless steel brush. Measures
should be taken to avoid contamination with iron impurities in
manufacturing and processing machinery such as shears, presses and
rolling machines. The processing site should be clean and separate
from the carbon steel processing site.
The welding groove of monel 400 material should be finished by
mechanical processing method. If the groove is polished, the local
overheating should be avoided. Due to the obvious physical
properties of nickel alloy and high-alloy stainless steel compared
with carbon steel, their thermal conductivity coefficient is low,
and the thermal expansion coefficient is large, for this point
welding method to use clamping, large foot (1-3mm) method to solve.
Due to the poor fluidity of monel 400 material, a large groove
Angle (60-70°) was designed to allow the wire to fill the weld
seam. Cleaning groove and welding rod with acetone before welding,
welding method with GTAW is ok, welding wire with ernicu-7. Monel
400 before welding does not need preheating, generally do not need
post-welding heat treatment, because the processed material
strength has been improved, for the future use of certain benefits.