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Precision alloys with set elasticity properties

This page contains the alloy description: physical and mechanical properties, applications, grades and types of products.

Main information

Precision alloys with set elasticity properties - alloys with high stability towards slight plastic deformations and relaxation resistance under static and cyclic loads; they are used as springs and spring elements, elastically sensitive elements of instruments, diaphragms of flow meters, resonators of filters for choosing, generating and tuning for a set frequency.

Relaxation resistance - a material ability to resist relaxation (e.g., stress); relaxation - self-active load damping fall within time that occurs due to transition of elastic deformation into plastic deformation. Typical relaxation example - reduction of tension of bolts and studs in flange connections. Although the bolts are initially tightened, they get loosened due to the partial transition of elastic deformation into plastic deformation under high temperatures.

These materials are based on several systems:
  • Precipitation hardening alloys
  • Deformation hardening alloys
    • Co-Cr-Ni (cobalt-chromium-nickel)
    • Fe-Cr-Ni (iron-chromium-nickel)
    • Mo-Re (molybdenum-rhenium)
  • Alloys with a temperature stable modulus of elasticity
    • Fe-Ni-Cr (iron-nickel-chromium)
    • Fe-Ni-Co (iron-nickel-cobalt)


Precision alloys with set elasticity properties can be conditionally divided by hardening form and physico-mechanical properties.
Table 1
Grade General specification Intended use
Precipitation hardening alloys
36NiCrTiAl (EI702)
36NiCrTiAl5Mo (EP51)
36NiCrTiAl8Mo (EP52)
47CrNiMo-VI (EP530)
High strength and elastic properties, relaxation stability under -269 - 250-700 °С, corrosive stability in air conditions and several aggressive media, non-magnetization Elastic sensitive elements - diaphragms, bellows boots, Bourdon tubes, aneroid chambers, coil and flat springs, parts of vacuum-tube devices, automation units working in aggressive media and wide temperature range
40CrNiAl-VI (EP793) High hardness, corrosive stability in sea and tropical climate, non-magnetization Centerpunches, device bearings, cutting medical tools
67CoNi5Nb-VI High strength and elastic properties, relaxation stability under temperature up to 400-450 °С, low nominal resistance Current-conducting elastic elements, fixed contacts of electromagnetic and mercury-contact relays
55NbNiAl Relaxation stability under temperature up to 500 °С, low modulus of elasticity, low EMTC, high corrosive stability in aggressive media, non-magnetization Critical elastic sensitive parts for working in aggressive media and under temperatures up to 400-500 °С
Deformation-hardening alloys
High strength and elastic properties, non-magnetization, corrosive stability, longevity, wear resistance Mainsprings of spring engines and watches, coil cylindrical springs, centerpunches of electric-measuring instrument, surgical parts, tension and torque members (40CoCrNiMoW)
45CoCrWNi High hardness, wear resistance, elasticity and thermal stability properties under temperatures up to 500-600 °С, corrosive stability, non-magnetization Communication device styluses, frames of artificial heart valves
40Co27CrNiMo with Та Electrochemical stability in a saline solution and human body, longevity Pacemaker cores and parts, anti-thrombotic filters, acupuncture needles
High strength properties, thermal stability up to 250 °С, corrosive stability in some environments General-purpose springs, roll springs
12CrNiCoMoTiAl High strength and elastic properties, high survivability, corrosive stability Mainsprings of seat belts, roll springs of brush holders of electric machine
50MoI High strength and elastic properties, relaxation stability under temperature up to 900 °С Tension and torque members, torque members working under high temperatures
Alloys with a thermally stable modulus of elasticity (elinvars)
Thermal stability of modulus of elasticity under temperatures from -269 to +100-200 °С, high strength and elastic properties Elastic sensitive elements of precision devices, flow meters, speed controllers, linear accelerometers, liquid density meters, dynamometers of digital electronic scales, clockwork haircoils (42NiCrTiAl)
30Ni25CoTiAl (EK4)
Thermal stability of modulus of elasticity under temperatures from 300-400 °С. Increased mechanical properties Pressure and temperature gauges of bottom-hole apparatus, flow meters
43NiCrWTi High positive temperature coefficient of frequency (TCF), (+50)-(+70)·10-6К-1 Electromechanical filters with piezoceramic converters
45NiCrTi (EP218) Minimal TCF (±5·10-6К-1) within -40 - +60°С Resonators of electromechanical filters
37Ni11Cr (EP297)
Low temperature coefficient of modulus of elasticity under temperature up to 100 °С, high corrosive stability Precision elastic sensitive elements working in low-aggressive environments
U8/75Ni34Cr8MnЗ (EP636)
Turning-fork bimetal with minimal TCF (below 3·10-6К-1) Turning-fork generators, frequency stabilizers
90NbTi Non-magnetic elinvar with low modulus of elasticity Elastic sensitive elements, delay lines, electromechanical filters


Precision materials with set elasticity properties should comply with the following requirements: they should have a high or, vice versa, low modulus of elasticity, low temperature coefficient of the modulus of elasticity, high quality factor, low elastic hysteresis (in the theory of elasticity hysteresis occurs in elastic materials that can maintain deformation under high pressure and lose it under return pressure (e.g., stretching of the fixed column)), elastic time-effect, high fatigue limit, corrosive stability, non-magnetization, electric conductivity, wear resistance and stability of these properties under operation temperatures. These materials should have a process plasticity for making elastic elements with a set configuration and weldability.


The main grades of precision alloys of the considered class are given in Classification section, Table 1. The chemical composition and other requirements are regulated by GOST 10994-74.


Products made of precision alloys with set elasticity properties are used in many industries: production of elastic sensitive elements, sensors; different types of springs, medical tools.

Precipitation hardening alloys are applied for making the following products: elastic sensitive elements working within -250-400 °С depending on the certain material grade; pressure gauges working within -253-250 °С; power and belleville springs used in underground well equipment for extracting natural gas containing hydrogen sulphide. Also some grades can be applied as corrosive construction materials.

Deformation-hardening materials are used in heat-resistant springs and mainsprings; centerpunches of electric-measuring instruments; geodesic and gyroscopic devices (for elastic elements in micron sections); flat diaphragms; elastic torque members working under high temperatures in vacuum or inert gases and hydrogen.

Alloys with a thermally stable modulus of elasticity are widely applied in instrument engineering for producing elastic sensitive elements of ultrathin instrumentation and controls without temperature control and compensation. They are used for making haircoils and hair of special clockworks, flat, coil and helical springs, resonators of electromechanical filters, aneroid chambers, bellows boots, acoustic ducts, Bourdon tubes, engine speed controllers, pressure gauges.

Elastic alloy application in medicine is worth mentioning individually. Biocompatibility is the general requirement towards materials used in medical equipment (especially to those implanted into the human body). The materials should not cause clots or inflammations and should have the required mechanical properties (elasticity, fatigue strength, etc). 36NiCrTiAl grade is used for entry needles made of thin-wall tubes with diameter 0.8-2.0 mm. 40CoCrNiMo alloy is applied for clamps for stitching vessels, prosthetic repair of the eye-ball stump, for bone surgery in orthopedics - “pegs” for bone fastening, joint prostheses, for wound springs used for bone union under pressure; for short-term cardiac activation, etc. 40Co27CrNiMo grade with Та has a higher corrosive stability in the human body and saline solution than 40CoCrNiMo alloy. The main applications are electrodes for long-term and continuous activation of tissues and organs (heart, brain, bladder, gastrointestinal tract, etc.) made of wire with diameter 0.15-0.2 mm with 30-40% deformation. Besides that, the wire of this alloy is used for making acupuncture needles, elastic corrective facilities applied in surgery for treating spinal curvature and bone ruptures so as correcting the lower limb axis. Strips 0.13-0.15 mm thick with 30-40% deformation are used for making anti-thrombotic filters. A softened hot-rolled sheet 5-12 mm thick and wire with diameter 0.9-1.1 mm and 30-40% deformation are used for making frames of artificial heart valves. 40CrNiAl-WI alloy is used for making general surgical lancets due to high wear resistance and corrosive stability. Such lancets have better operational properties than mass-produced steel lancets.


Materials with set elasticity properties are produced in form of flat (strips, flat bars and sheets) and round products (wire, rods and pipes). The certain application determines the use of the blanks.


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