# Alloy713LC and IN738: A Comparative Analysis of High-Temperature Performance
## Introduction
High-temperature alloys play a crucial role in modern industrial applications, particularly in aerospace and power generation sectors. Among these, Alloy713LC and IN738 stand out as two prominent nickel-based superalloys. This article provides a comprehensive comparison of their high-temperature performance characteristics.
## Composition and Microstructure
### Alloy713LC Composition
Alloy713LC is a low-carbon variant of the Alloy713 family, primarily composed of:
– Nickel (base)
– Chromium (12-14%)
– Molybdenum (4-5%)
– Aluminum (5.5-6.5%)
– Titanium (0.5-1.0%)
### IN738 Composition
IN738 features a more complex composition:
– Nickel (base)
– Chromium (15-17%)
– Cobalt (8-9%)
– Molybdenum (1.5-2.0%)
– Tungsten (2.4-2.8%)
– Aluminum (3.4-3.8%)
– Titanium (3.4-3.8%)
The higher chromium content in IN738 provides better oxidation resistance, while its complex γ’ phase contributes to superior creep resistance.
## Mechanical Properties at Elevated Temperatures
### Tensile Strength
At 850°C, Alloy713LC demonstrates a tensile strength of approximately 850 MPa, while IN738 shows slightly higher values around 900 MPa. The difference becomes more pronounced at higher temperatures, with IN738 maintaining better strength retention above 900°C.
### Creep Resistance
IN738 outperforms Alloy713LC in creep resistance, particularly in the 750-950°C range. This is attributed to its optimized γ’ phase distribution and higher volume fraction of strengthening precipitates. The 1000-hour rupture strength of IN738 at 850°C is about 30% higher than that of Alloy713LC.
## Oxidation and Corrosion Resistance
### Oxidation Behavior
Both alloys form protective oxide scales, but IN738’s higher chromium content provides superior oxidation resistance above 900°C. In cyclic oxidation tests, IN738 shows approximately 20% less weight loss than Alloy713LC after 1000 hours at 950°C.
### Hot Corrosion
IN738 demonstrates better resistance to Type I (high-temperature) hot corrosion due to its optimized chromium and cobalt content. However, Alloy713LC performs comparably in Type II (low-temperature) hot corrosion environments.
## Applications and Limitations
### Typical Applications
Alloy713LC finds use in:
– Turbine blades for aircraft engines
– Industrial gas turbine components
– High-temperature fasteners
IN738 is preferred for:
– Stationary gas turbine blades and vanes
Keyword: Alloy713LC IN738
– High-stress components in power generation
– Applications requiring extended service life at extreme temperatures
### Limitations
Alloy713LC’s lower chromium content limits its use in highly oxidizing environments, while IN738’s complex composition makes it more expensive and difficult to process. Both alloys require careful heat treatment to achieve optimal properties.
## Conclusion
The choice between Alloy713LC and IN738 depends on specific application requirements. While IN738 generally offers superior high-temperature performance, Alloy713LC provides a cost-effective solution for less demanding environments. Understanding their comparative strengths enables engineers to make informed material selection decisions for high-temperature applications.
