The important nickel alloys are haste alloy, Monel metal, inconel, nomonic and ni-chrome.
1 Haste Alloy or high Temprature Alloy
Haste alloy or high temperature alloy is mainly a nickel base alloy. It contains
Ni = 45%,
Cr = 22%,
Mo = 9%,
Co = 1.5%,
W = 0.5%,
C = 0.15% and
Fe = Remaining
(i) It can be hot and easily cold worked, casted and welded.
(ii) It has high resistance corrosion especially to acids and salts except nitric acid (HNO3).
(iii) It can be machined also.
(iv) This alloy is used where the resistance to corrosion is of consideration.
The high temperature alloys are those alloys which can withstand high temperatures about 1100°C. These alloys are used in components of nuclear plants, jet and rocket engines etc.
2 Monel Metal
Monel metal is an important alloy of nickel and copper. It contains 68% Ni, 30% Cu, 1% Fe and small amount of other constituents like iron, manganese, silicon and carbon.
Monel metal is superior to brass or bronze in resisting corrosion and in retaining its strength at high temperature. It is magnetic at ordinary temperatures. Its mechanical properties are improved by cold working. It can be cast, cold and hot worked, forged and welded. It resembles nickel in appearance and is strong, ductile and tough. It has good mechanical properties and can retain them even at elevated temperatures. It has high excellent corrosion resistance.
Monel metal is also used for pump fittings, condenser tubes, sea water exposed parts etc. It is widely used for making turbine blades, containers, parts for chemical plants, food handling machinery parts, marine parts, pump impellers, propellers, evaporators and heat exchangers in chemical works.
Ni = 80%
Cr = 14%
Fe = 6%
Inconel has high resistance to corrosion and oxidation at elevated temperatures. It can be readily cold-worked and hot-worked, but does not respond to heat treatment. It contains high mechanical properties coupled corrosion and heat resisting properties. It can be cast, forged, rolled and cold drawn. Its specific gravity is 8.55 and melting point is 1395°C. Its Brinell Hardness is about 160BHN. It can be soft soldered or can be welded by oxyacetylene welding.
Inconel is used for making springs, exhaust manifold of aircraft engines, machinery for food processing industries, especially milk and milk products. It is widely used for processing uranium and for sheathing for high temperature heating elements.
4 Nomonic alloy
The composition of nomonic alloy is given as under.
Cr = 15 to 18%
Co = 15 to 18%
Ti = l.2 to 4.0%
Al = l.5%
Ni = Remaining
(i) Nomonic is a special type of nickel alloy having good strength
(ii) It can be easily heat treated to attain excellent properties for very high temperature service.
Nomonic is widely used for making gas turbine engines
Ni = 60%
Cr = 15%
Fe = 20%
Ni-chrome is non-corrosive. It can easily withstand high temperatures without oxidation.
Ni-chrome is commonly used for making electrical resistance wire for electric furnaces and heating elements.
Reference Introduction to basic Manufacturing Processes and Workshop Technology by Rajender Singh.
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