Uses and applications of nickel alloys

TAGS: Nickel alloys | nickel | alloy | grade |

Due to its good mechanical strength, ductility and high chemical stability, nickel is widely used in stainless steel, electroplating, batteries, chemical industry and other fields, basically covering various industries from civil products to aerospace, missiles, submarines, nuclear reactors, etc. It has become an indispensable metal for the development of modern aviation industry, national defense industry and the modernization system of establishing a high level of material and cultural life for human beings.

01 Definition of Nickel

Pure nickel is a silver-white metal with a high melting point (1455 degrees), good mechanical properties and cold and hot pressure processing functions, and corrosion resistance. It is a good material for heat-resistant concentrated alkali solution corrosion, neutral and slightly acidic solutions and organic Solvent, chemically stable in the atmosphere, fresh water and sea water, but not resistant to corrosion by oxidizing acids and high-temperature sulfur-containing gases. It is generally used as a corrosion-resistant structure of machinery and chemical equipment, structural parts of precision instruments, parts of electronic tubes and radio equipment, instruments and tableware in the food industry, etc.

02 nickel alloy

Nickel alloy, also known as nickel-based alloy, is an alloy composed of nickel as the base and adding other elements. The Monel alloy containing about 30% copper produced around 1905 is an earlier nickel alloy. Nickel has good mechanical, physical and chemical properties. Adding appropriate elements can improve its oxidation resistance, corrosion resistance, high temperature strength and improve certain physical properties. It has a wide range of applications in chemical, electronic, medical, aerospace and other departments. use.

03Classification and characteristics of nickel alloy

Nickel alloys can be divided into:

(1) Nickel-based superalloys: The main alloying elements are chromium, tungsten, molybdenum, cobalt, aluminum, titanium, boron, zirconium, etc. Among them, chromium plays the role of anti-oxidation and anti-corrosion, and other elements play the role of strengthening. It has high strength, oxidation resistance and gas corrosion resistance at high temperatures of 650-1000 ° C. It is the most widely used and highest high-temperature strength alloy among superalloys. It is used to manufacture aero-engine blades and high-temperature components on rocket engines, nuclear reactors, and energy conversion equipment.

(2) Nickel-based corrosion-resistant alloys: the main alloying elements are copper, chromium, and molybdenum. It has good overall performance and is resistant to various acid corrosion and stress corrosion. The earliest application is nickel-copper alloy, also known as Monel alloy; in addition, there are nickel-chromium alloy, nickel-molybdenum alloy, nickel-chromium-molybdenum alloy, etc. Used in the manufacture of various corrosion-resistant parts.

(3) Nickel-based wear-resistant alloy: the main alloying elements are chromium, molybdenum, and tungsten, and also contain a small amount of niobium, tantalum, and indium. In addition to its wear resistance, its oxidation resistance, corrosion resistance and welding performance are also good. It can be used to manufacture wear-resistant parts, and can also be used as a cladding material, which can be clad on the surface of other base materials through surfacing welding and spraying processes.

(4) Nickel-based precision alloys: including nickel-based soft magnetic alloys, nickel-based precision resistance alloys and nickel-based electrothermal alloys, etc. The most commonly used soft magnetic alloy is permalloy with about 80% nickel, which has high maximum and initial permeability and low coercive force, and is an important iron core material in the electronics industry. The main alloying elements of nickel-based precision resistance alloys are chromium, aluminum, and copper. This alloy has high resistivity, low temperature coefficient of resistivity and good corrosion resistance, and is used to make resistors. Nickel-based electric heating alloy is a nickel alloy containing 20% chromium, which has good oxidation resistance and corrosion resistance, and can be used for a long time at a temperature of 1000-1100 °C.

(5) Nickel-based shape memory alloy: a nickel alloy containing titanium. The recovery temperature is 70°C, and the shape memory effect is good. A small change in the proportion of nickel-titanium components can change the recovery temperature within the range of 30-100°C. It is mostly used in the manufacture of self-expanding structural parts used in spacecraft, self-exciting fasteners used in the aerospace industry, and artificial heart motors used in biomedicine.

04Application of nickel alloy in product design

Home appliances, transportation, kitchen and bathroom

05Forming process

Common metal casting processes, stamping processes, etc. are common methods of nickel alloy processing.

(1) Forging: Forging is the most common metal processing process, by repeatedly heating and hammering the metal until the desired shape is obtained. Suitable for single piece and small batch production.

Process flow: open and closed die forging: the heated metal block is hammered into shape through the upper and lower dies, used to extend the metal shape, and must be manually operated by experienced operators; closed die forging: the heated metal block (yellow part) is passed through the upper and lower dies Hammer forming for rapid prototyping of metals

(2) Stamping forming: It is a metal cold treatment processing method, also known as cold stamping or sheet metal stamping. With the power of stamping equipment, the metal sheet is directly formed by force in the mold. The stamped parts are widely used in automobiles. Manufacture of parts and manufacture of household appliances. Suitable for mass production.

Process flow: fix the metal sheet on the mold table → the punch falls vertically to form the metal sheet under force inside the mold → the punch rises, and the parts are taken out to wait for the next trimming and polishing process. The whole process takes about 1s-1min

(3) Lost wax molding: It is a precision casting process with less cutting or no cutting. The dimensional accuracy and surface quality of the produced castings are higher than other precision casting methods.

Process flow:

Step 1: Inject the molten liquid wax into the metal mold prepared in advance, and form multiple wax parts after cooling and solidifying

Step 2: Taking advantage of the low melting point of wax, connect individual wax parts into a tree structure

Step 3: Soak the assembled wax tree structure in the ceramic slurry

Step 4: Spray high temperature and fireproof particles on the ceramic surface

Step 5: In a high temperature oven at 500°-1095°, the wax inside will melt and drain away, forming a hollow ceramic tree structure

Step 6: Inject molten liquid metal (gray part) and fill the hollow cavity of the ceramic

Step 7: After the liquid metal in the cavity is completely cooled and solidified, break the hard ceramic shell on the outer surface, and finally cut and separate the individual metal parts from the tree structure

06 Nickel alloy detection

Qualified nickel alloys require the following tests:

Oxidation resistance, salt spray test, coefficient of thermal expansion, atmospheric corrosion, tensile strength, fatigue strength, shear strength, tensile creep, stress relaxation, fracture analysis, metallographic analysis, bending test, etc.