title = "Stress Relieving: When and How to Apply"

content = """
Stress relieving is a heat treatment designed to reduce residual stresses in metal parts and assemblies without significantly altering microstructure or mechanical properties. Residual stresses are introduced by manufacturing operations including welding, casting, machining, cold forming, and thermal gradients during heat treatment. These stresses can cause dimensional instability (part movement during machining), stress corrosion cracking, fatigue crack initiation, and distortion during service. At Ridgecrest Metalworks, stress relieving is applied before precision machining of large weldments, after welding of pressure vessels (where code requires it), and for components that exhibit dimensional instability.

For carbon and low-alloy steels, stress relief is typically performed by heating to 1050–1200°F (565–650°C)—below the Ac1 lower critical temperature so no phase transformation occurs—and holding for 1 hour per inch of maximum section thickness (minimum 1 hour). The furnace temperature is brought up slowly (typically no faster than 200–300°F/hr / 110–165°C/hr for heavy sections) to avoid adding new thermal stresses. After the hold, the part is cooled slowly in the furnace (maximum 200–300°F/hr) through the range down to at least 600°F (315°C) before being removed to ambient air. Fast cooling from the stress relief temperature would reintroduce thermal stresses—defeating the purpose.

The stress relief temperature must not exceed the tempering temperature used for previously hardened components; otherwise, the component will be softened. For hardened-and-tempered parts, stress relief must be performed at 50–100°F (28–55°C) below the tempering temperature used.

Stainless steels require different conditions: austenitic stainless (304, 316) does not respond to stress relief in the same way as carbon steel; it is solution annealed (high temperature) to relieve stress. Precipitation-hardening stainless steels are stress relieved at sub-aging temperatures. Aluminum alloys are stress relieved by stretching (mechanical) or by low-temperature thermal treatment.

After stress relieving, hardness testing verifies that no unintended softening occurred. For precision components, dimensional measurement before and after stress relief confirms that the part has reached dimensional stability.
"""

version = "0.0.1"
