Super Alloy HASTELLOY(r) G™ (UNS N06007)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
     Machinability
     Forming
     Welding
     Forging
     Cold working
     Annealing
     Hardening
Applications

Introduction

Super alloys are metallic alloys used at high temperatures above 540ºC (1000ºF) where high surface stability and deformation resistance are mainly required. Three major classes of super alloys include iron-base, nickel-base and cobalt-base alloys. The iron-base super alloys are generally wrought alloys with stainless steel technology. Nickel-base and cobalt-base super alloys may be cast or wrought based on its composition or application. Super alloys are commonly forged, rolled to sheet or produced in various shapes. However, highly alloyed compositions are produced as castings.

The following datasheet provides a detailed description of HASTELLOY(r) G™, which has good resistance to both oxidation and reduction.

Chemical Composition

The following table shows the chemical composition of HASTELLOY(r) G™.

Element Content (%)
Chromium, Cr 21-23.5
Iron, Fe 18-21
Molybdenum, Mo 5.5-7.5
Cobalt, Co 2.5 max
Niobium, Nb 1.75-2.5
Copper, Cu 1.5 min
Manganese, Mn 1-2
Silicon, Si 1 max
Tungsten, W 1 max
Carbon, C 0.05 max
Phosphorus, P 0.04 max
Sulfur, S 0.03 max
Nickel, Ni Remainder

Physical Properties

The physical properties of HASTELLOY(r) G™ are given in the following table.

Properties Metric Imperial
Density 8.91 g/cm³ 0.322 lb/in³
Melting point 1343ºC 2450ºF

Mechanical Properties

The mechanical properties of HASTELLOY(r) G™ are given in the following table.

Properties Metric Imperial
Tensile strength Min 760 MPa Min 110000 psi
Yield strength (0.2% offset) 700-860 MPa 102000-125000 psi
Modulus of elasticity (room temperature) 192 GPa 27800 ksi
Elongation at break Min 20% Min 20%
Hardness, Brinell ( estimated from Rockwell C for Brinell 10 mm ball/3000 kg load) 290 290
Hardness, Knoop (estimated from Rockwell C) 345 345
Hardness, Rockwell A (estimated from Rockwell C) 66 66
Hardness, Rockwell C Max 31 Max 31
Hardness, Vickers (estimated from Rockwell C) 300 300

Thermal Properties

The thermal properties of HASTELLOY(r) G™ are given in the following table.

Properties Metric Imperial
Thermal expansion co-efficient (@20ºC/68ºF) 13 µm/m°C 7.22 µin/in°F

Other Designations

Equivalent materials to HASTELLOY(r) G™ are the following:

  • ASTM B581
  • ASTM B582
  • ASTM B619
  • ASTM B622
  • ASTM B626
  • DIN 2.4618

Fabrication and Heat Treatment

Machinability

HASTELLOY(r) G™ can be machined using conventional techniques employed for iron based alloys. The quality of the alloy can be improved with the utilization of water-base coolants. Heavy duty machining tools and equipment can be used prior to cutting in order to reduce chattering or work-hardening of the alloy.

Forming

HASTELLOY(r) G™ can be formed through conventional forming methods.

Welding

Welding of HASTELLOY(r) G™ is performed through commonly used welding techniques like gas tungsten arc welding, shielded metal-arc welding, metal-arc welding and submerged-arc welding. However, an alloy filler metal that suits this alloy should be used.

Forging

HASTELLOY(r) G™ can be forged at 927 to 1149ºC (1700 to 2100ºF).

Cold working

HASTELLOY(r) G™ can be cold worked using standard tooling methods. As plain carbon steels has an ability to produce galling, they are not preferred for forming HASTELLOY(r) G™. Galling can be minimized with the help of heavy duty lubricants.

Annealing

Annealing of HASTELLOY(r) G™ can be performed at 1177ºC (2150ºF) followed by rapid cooling of air and water quenching.

Hardening

HASTELLOY(r) G™ can be hardened by cold working.

Applications

HASTELLOY(r) G™ finds its application in wet flue gas desulfurization process and manufacture of chemical process equipment.

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