There are a plethora of steel grades in global space ecosystem — an industry where precision, strength and innovation intersect to push the boundaries of exploration constantly. Launch vehicles and satellites operate in extreme environments, facing challenges like intense mechanical stresses, temperature fluctuations and corrosive conditions in space and on ground - during testing. The selection of steel for these applications is not just about strength but also about achieving the perfect balance of properties tailored for specific tasks with high reliability.

The Starship is an engineering marvel and metallurgical masterpiece of the current decade, redefining the possibilities in aerospace technology and space exploration. SpaceX's Starship is constructed primarily from stainless steel, chosen for its strength, durability and cost-effectiveness. The vehicle comprises two main components: the Super Heavy booster ( ~70 m height and ~9 m dia) and the Starship spacecraft ( ~50 m height and ~9 m dia). The outer hull of Super Heavy Booster is estimated to use ~ 20 to 25 tons of stainless steel. The outer hull of Starship is estimated to use ~ 15 to 20 tons of stainless steel. Additional steel is utilized in internal structures, tanks and other elements, contributing to the overall mass of the vehicle [1,2,3].
Starship's development represents a bold step toward transforming humanity into a multiplanetary species. It is not merely a spacecraft but a symbol of what human ingenuity can achieve when pushing the limits of possibility. Metallurgists and materials science engineers play a significant role in SpaceX's mission to revolutionize space technology, with expertise in expertise is crucial in areas such as material selection, process development and quality assurance for components like rocket engines, spacecraft structures and thermal protection systems. SpaceX employs a substantial number of metallurgists and materials science engineers with a dedicated team for materials engineering.
From maraging steels renowned for their exceptional toughness in rocket motor casings, to austenitic stainless steels prized for their corrosion resistance in cryogenic systems, each steel type is a masterpiece of engineering. Specialized aerospace steels showcase the innovative potential of metallurgy in creating materials that can withstand the unique challenges of space exploration.
By understanding these materials and their applications, we not only delve into the science of alloys but also becoming part of a metallurgical legacy that shapes the future of space technology. This knowledge is a gateway to exciting opportunities in research, development and the pursuit of engineering excellence in one of the most inspiring fields of our time.
Maraging Steels
Grades: 18Ni (250, 300, 350)
Properties:
Extremely high strength
Excellent toughness
Easily machinable and weldable
Used for rocket motor casings and structural components
Austenitic Stainless Steels
Grades: AISI 304, 316, 321, 347
Properties:
High corrosion resistance
Non-magnetic
Retains strength at cryogenic temperatures
Used in fuel tanks and cryogenic storage systems
Martensitic Stainless Steels
Grades: 410, 420
Properties:
High strength and hardness
Moderate corrosion resistance
Typically used in high-stress components
Precipitation-Hardening (PH) Stainless Steels
Grades: 17-4PH, 15-5PH
Properties:
High strength and corrosion resistance
Used for structural components and load-bearing parts
High-Strength Low-Alloy (HSLA) Steels
Grades: AISI 4340, HY-80, HY-100
Properties:
High toughness
Excellent strength-to-weight ratio
Used in structural components and pressurized systems
Chromium-Molybdenum Steels
Grades: AISI 4130, 4140
Properties:
High strength and fatigue resistance
Good weldability
Common in airframe components and pressure vessels
Tool Steels
Grades: D2, H13, A2
Properties:
High hardness and wear resistance
Used in specialized applications like tooling for satellite assemblies
Low-Carbon Steels
Grades: SAE 1010, SAE 1020
Properties:
High ductility and weldability
Used in less-critical components
Specialized Aerospace Steels
Grades: Aermet 100, VascoMax C250, C300
Properties:
Ultra-high strength and toughness
Typically used in critical aerospace applications
Nickel-Based Steels
Grades: Invar 36, Kovar
Properties:
Low thermal expansion
High dimensional stability
Used in satellite structural frames and sensitive instrumentation mounts

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