Jul 24 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Machinability
Forming
Welding
Forging
Hot Working
Cold Working
Annealing
Hardening
Other Designations
Applications
Introduction
Sanicro 31HT alloy is an austenitic nickel-iron-chromium alloy that exhibits very good resistance to combustion gases, carburization, nitrogen absorption and oxidation. In addition, the alloy has high creep strength and good weldability and structural stability at high temperatures.
The alloy can be used at elevated temperatures of up to 1100°C (2010°F). When used at temperatures above 700°C (1290°F), the ductility of the alloy can be improved.
The following section will provide an overview of Sanicro 31HT alloy.
Chemical Composition
The chemical composition of Sanicro 31HT alloy is outlined in the following table.
Element |
Content (%) |
Iron, Fe |
46.7 |
Nickel, Ni |
30.5 |
Chromium, Cr |
20.5 |
Silicon, Si |
0.6 |
Manganese, Mn |
0.6 |
Aluminum, Al |
0.5 |
Titanium, Ti |
0.5 |
Carbon, C |
0.07 |
Phosphorous, P |
≤0.015 |
Sulfur, S |
≤0.010 |
Physical Properties
The following table shows the physical properties of Sanicro 31HT alloy.
Properties |
Metric |
Imperial |
Density |
7.90 g/cm3 |
0.285 lb/in3 |
Mechanical Properties
The mechanical properties of Sanciro 31HT alloy are displayed in the following table.
Properties |
Metric |
Imperial |
Tensile strength |
500-700 MPa |
72500-102000 psi |
Yield strength |
≥170 MPa |
≥24700 psi |
Elongation at break |
≥35% |
≥35% |
Rockwell B hardness |
≤90 |
≤90 |
Thermal Properties
The thermal properties of Sanicro 31HT alloy are given in the following table.
Properties |
Metric |
Imperial |
Thermal expansion co-efficient (@30-100°C/86-212°F) |
15 µm/m°C |
8.33 µin/in°F |
Thermal conductivity (@20°C/68°F) |
12 W/mK |
83.3 BTU.in/hrft².°F |
Fabrication and Heat Treatment
Machinability
Conventional machining techniques that are used for machining iron-based alloys can be used.
Forming
Sanicro 31HT alloy has excellent ductility, and can be readily formed by all conventional techniques.
Welding
The alloy can be welded using commonly used welding techniques such as gas-tungsten arc welding, shielded metal-arc welding, gas metal-arc welding and submerged-arc welding.
Forging
Sanicro 31HT alloy can be forged at 1010 to 1204°C (1850 to 2200°F) for 15 min and then air cooled.
Hot Working
The alloy can be hot worked at temperatures ranging from 871 to 1204°C (1600 to 2200°F).
Cold Working
Cold working may be performed using standard tooling.
Annealing
The alloy can be annealed to (2100°F) and air cooled.
Hardening
The alloy can be hardened only be cold working.
Other Designations
Other designations that are equivalent to Sanicro 31HT alloy include the following:
-
DIN 1.4959
-
DIN 1.4876
-
ASTM B407
-
ASTM B408
-
ASTM B409
Applications
The following are the list of applications of Sanicro 31HT alloy:
-
Heaters
-
Gas turbine components
-
Chemical process equipment
-
Fixtures
-
Heat exchangers