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What are the common Metal Surface Treatments?What is surface treatment technology?
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What are the common Metal Surface Treatments?What is surface treatment technology?

Views: 45     Author: Site Editor     Publish Time: 2018-06-29      Origin: www.fuchun-casting.com

Metals are easy to corrode and rust in the natural state, thus increasing the loss of metals and reducing the service life. Therefore, in order to increase the wear resistance, corrosion resistance, aesthetics and other functions of metals, it is necessary to protect the metal surface.


Metal surface treatment is a kind of technology which uses modern physical chemistry, metallurgy and heat treatment to change the condition and properties of metal surface, and optimize the combination of metal surface and material to meet the predetermined performance requirements. It is called metal surface treatment.


Mould surface treatment technology is a systematic engineering to obtain the required surface properties by changing the shape, chemical composition, structure and stress state of the mold surface through surface coating, surface modification or composite treatment technology.


Metal surface treatment performance refers to: wear resistance, corrosion resistance, friction coefficient, fatigue performance. Commonly used processing types are galvanizing, tin plating, copper plating, nickel plating, chromium plating, blackening, phosphating, spraying, polishing.



Galvanization refers to the surface treatment technology of plating a layer of zinc on the surface of metals, alloys or other materials for aesthetic and rust-proof purposes.

Galvanization on iron and steel parts is mainly used to prevent corrosion, and it is the most productive of all kinds of electroplating. Galvanization is widely used in light industry, Electromechanical industry and national defense industry because of its low cost, good corrosion resistance, beautiful appearance and storage resistance.


Tin plating:

Tin corrosion products are harmless to human beings and easy to braze. Tin plating is widely used in food canned packaging products, beverages, tableware and many parts of the electronic industry that need brazing.


Copper plating:

Copper plating is often used as the intermediate layer of other coatings to improve the adhesion of surface coatings and matrix metals. In the electric power industry, thick copper wire plating can be used instead of pure copper wire to reduce copper consumption.


Nickel plating:

The application of nickel plating is very wide. It can be used to protect decorative and functional two aspects. The former is mainly used for protective decorative coating of bicycles, clocks and watches, household appliances, hardware products, automobiles, cameras and other parts.The latter is mainly used for repairing and electroplating of wearable products.

Chromium plating:

Chromium can keep luster in air for a long time, and does not react in alkali solution, nitric acid, sulfuric acid and many organic acids. Chromium plating has high hardness, excellent wear resistance and low friction coefficient. Therefore, chromium plating is often used to protect decorative coatings, prevent rust of base metal and beautify appearance, and also to improve wear resistance of products. Or repair wear;



The surface of the steel parts has been blackened, and it is also known as bluing. The principle is that the surface of steel products is oxidized rapidly to form a dense oxide film protective layer, which improves the anti-rust ability of steel parts.



Phosphate conversion film is a process of chemical and electrochemical reaction to form phosphate chemical conversion film.The main purposes of phosphating are as follows: to protect the base metal from corrosion to a certain extent; to primer before painting, to improve the adhesion and corrosion resistance of the coating; to reduce friction and lubrication in metal cold working process;



Paint or powder is coated on the surface of the workpiece by pressure or electrostatic force, so that the workpiece has anticorrosion and decorative effect.



Modification of workpiece surface with flexible polishing tools and abrasive particles or other polishing media. Polishing can not improve the dimensional or geometrical accuracy of the workpiece, but to obtain a smooth surface or mirror gloss for the purpose, and sometimes to eliminate gloss.


In the traditional metal surface treatment technology, electroplating is one of the most widely used treatment methods, but the use of electroplating on the environment is very serious pollution, so the country is gradually reducing the use of electroplating, in order to effectively replace the use of electroplating, a new generation of environmentally friendly special surface alloy catalytic solution, simple operation procedures, investment Low cost, in line with national environmental standards, metal surface treatment technology is particularly widely used.

Metal surface treatment



  • What is 'multiple certification'?

    This is where a batch of steel meets more than one specification or grade. It is a way of allowing melting shops to produce stainless steel more efficiently by restricting the number of different types of steel. The chemical composition and mechanical properties of the steel can meet more than one grade within the same standard or across a number of standards. This also allows stockholders to minimise stock levels.

    For example, it is common for 1.4401 and 1.4404 (316 and 316L) to be dual certified - that is the carbon content is less than 0.030%. Steel certified to both European and US standards is also common.

  • What surface finishes are available on stainless steels?

    There are many different types of surface finish on stainless steel. Some of these originate from the mill but many are applied later during processing, for example polished, brushed, blasted, etched and coloured finishes.

    The importance of surface finish in determining the corrosion resistance of the stainless steel surface cannot be overemphasised. A rough surface finish can effectively lower the corrosion resistance to that of a lower grade of stainless steel.

  • Can I use stainless steel at high temperatures?

    Various types of stainless steel are used across the whole temperature range from ambient to 1100 deg C. The choice of grade depends on several factors:

    1. Maximum temperature of operation
    2. Time at temperature, cyclic nature of process
    3. Type of atmosphere, oxidising , reducing, sulphidising, carburising.
    4. Strength requirement

    In the European standards, a distinction is made between stainless steels and heat-resisting steels. However, this distinction is often blurred and it is useful to consider them as one range of steels.

    Increasing amounts of Chromium and silicon impart greater oxidation resistance. Increasing amounts of Nickel impart greater carburisation resistance.

  • Can I use stainless steel at low temperatures?

    Austenitic stainless steels are extensively used for service down to as low as liquid helium temperature (-269 deg C). This is largely due to the lack of a clearly defined transition from ductile to brittle fracture in impact toughness testing.

    Toughness is measured by impacting a small sample with a swinging hammer. The distance which the hammer swings after impact is a measure of the toughness. The shorter the distance, the tougher the steel as the energy of the hammer is absorbed by the sample. Toughness is measured in Joules (J). Minimum values of toughness are specified for different applications. A value of 40 J is regarded as reasonable for most service conditions.

    Steels with ferritic or martensitic structures show a sudden change from ductile (safe) to brittle (unsafe) fracture over a small temperature difference. Even the best of these steels show this behaviour at temperatures higher than -100 deg C and in many cases only just below zero.

    In contrast austenitic steels only show a gradual fall in the impact toughness value and are still well above 100 J at -196 deg C.

    Another factor in affecting the choice of steel at low temperature is the ability to resist transformation from austenite to martensite. 

  • Is stainless steel non-magnetic?

    It is commonly stated that “stainless steel is non-magnetic”. This is not strictly true and the real situation is rather more complicated. The degree of magnetic response or magnetic permeability is derived from the microstructure of the steel. A totally non-magnetic material has a relative magnetic permeability of 1. Austenitic structures are totally non-magnetic and so a 100% austenitic stainless steel would have a permeability of 1. In practice this is not achieved. There is always a small amount of ferrite and/or martensite in the steel and so permeability values are always above 1. Typical values for standard austenitic stainless steels can be in the order of 1.05 – 1.1. 

    It is possible for the magnetic permeability of austenitic steels to be changed during processing. For example, cold work and welding are liable to increase the amount of martensite and ferrite respectively in the steel. A familiar example is in a stainless steel sink where the flat drainer has little magnetic response whereas the pressed bowl has a higher response due to the formation of martensite particularly in the corners.

    In practical terms, austenitic stainless steels are used for “non-magnetic” applications, for example magnetic resonance imaging (MRI). In these cases, it is often necessary to agree a maximum magnetic permeability between customer and supplier. It can be as low as 1.004.

    Martensitic, ferritic, duplex and precipitation hardening steels are magnetic.

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