Electric Boat Submarine Hull Bonding Investigation

Overview

In this task, you will explore the metallurgy of submarine hull bonding, using a simulation to investigate how the molecular-level structure of metals and their interactions determine the macroscopic properties and integrity of a submarine hull.

Estimated Time: 45 minutes Materials: Electric Boat Submarine Hull Bonding Simulation, this handout.

Part 1: Engage (Anchoring Phenomenon)

Modern submarines, like those built by General Dynamics Electric Boat, dive to incredible depths where the pressure is immense. To survive, the submarine’s hull must be incredibly strong and tough. The hull is made by welding together large curved plates of special steel. If the weld is not performed correctly, the hull may fail catastrophically under pressure. Why might the way we join two pieces of metal affect the overall strength of the submarine? Write down your initial thoughts and questions about what could go wrong during the welding process at a microscopic level.

Part 2: Explore (Simulation Investigation)

Open the Electric Boat Submarine Hull Bonding Simulation. Follow the steps below to investigate how different parameters affect the weld integrity.

Variables to Change:

Instructions:

  1. Set the Alloy Composition to HY-80 Steel.
  2. Set the Shielding Gas to None. Leave Thermal Energy at 3000 J/s. Click and drag across the macro canvas to weld.
  3. Observe the resulting Microstructure view and the Structural Integrity score. Record this in your data table.
  4. Reset the system. Change the Shielding Gas to Argon and repeat the weld. Record your observations.
  5. Reset the system. Keep Argon as the gas, but test the extremes of Thermal Energy (1000 J/s and 5000 J/s) using HY-100 Steel.
  6. Finally, test Mild Carbon Steel with Argon at 3000 J/s.

Sample Data Table:

Alloy Shielding Gas Thermal Energy (J/s) Structural Integrity (%) Microstructure Observations
HY-80 None 3000    
HY-80 Argon 3000    
HY-100 Argon 1000    
HY-100 Argon 5000    
Mild Carbon Argon 3000    

Part 3: Explain (Sensemaking)

Using the data you collected from the simulation, answer the following questions:

  1. Effect of Shielding Gas: What happened to the microstructure and structural integrity when no shielding gas was used compared to when Argon was used? Explain the role of the shielding gas in terms of atomic interactions.
  2. Thermal Energy and Cooling: How did insufficient thermal energy (1000 J/s) and excessive thermal energy (5000 J/s) affect the weld’s integrity and microstructure? Relate this to the arrangement of molecules and the rate of cooling.
  3. Alloy Composition: Why did the Mild Carbon Steel result in lower structural integrity compared to HY-80 or HY-100, even when using optimal welding parameters? Discuss the molecular-level structure of these materials.

Part 4: Elaborate/Evaluate (Argumentation & Modeling)

Deliverable: You are a metallurgical engineer tasked with presenting the optimal welding procedure for a new deep-dive submarine hull. Create an evidence-based recommendation that includes:

  1. The optimal combination of Alloy, Shielding Gas, and Thermal Energy.
  2. A written explanation of why this combination works best, referencing the molecular-level structure of the chosen material and how attractive and repulsive electrical forces determine the macroscopic properties (like strength and toughness).
  3. Include a simple drawn model or description (using geometric shapes or structures) showing how the atoms are arranged in a strong, tough weld versus a weak, brittle weld.

Teacher Notes