Exam 1: Corrosion and Materials

_________ is surface initiated cracks caused by environmental cracking of 300 Series SS and some nickel based alloys under the combined action of tensile stress, temperature and an aqueous chloride environment. The presence of dissolved oxygen increases the propensity for cracking.

Spheroidization and graphitization are competing mechanisms that occur at overlapping temperature ranges. Spheroidization tends to occur preferentially above _______ while graphitization predominates below this temperature.

A form of mechanical fatigue in which cracks are produced as a result of dynamic loadings is _______.

Titanium Hydriding damage occurs primarily in sour water strippers and amine units in the overhead condensers, heat exchanger tubes and other titanium equipment operating above _________.

SIMULATION Ways to prevent thermal fatigue include reducing stress concentrators by making _______________ transitions at places where the wall thickness changes.

Alloy 400 is susceptible to LME when it comes in contact with molten ________.

_________ is the result of cyclic stress caused by variations in temperature.

For a specific material, HTHA is dependent on temperature, hydrogen partial pressure, time and _________.

With cooling water corrosion, _________ oxygen content tends to ________ carbon steel corrosion rates.

Foul smelling water may be a sign of fouling and/or _______

The creep threshold temperature for 1 ¼, 2 ¼, 5 and 9 Cr is ________.

Steam blanketing is when the heat flow balance is disturbed; individual bubbles join to form a steam blanket, a condition known as Departure from Nucleate Boiling (DNB). Once a steam blanket forms, tube rupture can occur rapidly, as a result of _________.

Corrosion in boiler feedwater and condensate return systems is usually the result of dissolved gases, oxygen and _______.

Thermal fatigue cracks usually initiate on the _________ of the component. They are generally wide and filled with oxides due to the elevated temperatures.

Which of these materials are not susceptible to Spheroidization?

Cooling water corrosion can result in many different forms of damage including general corrosion, pitting corrosion, ________, stress corrosion cracking and fouling.

Since all fuels contain some amount of sulfur, sulfuric and sulfurous acid __________ can occur if the metal temperature is below this temperature.

The removal of a material's protective scale by impacting materials is called:

General or localized corrosion of carbon steels and other metals caused by dissolved salts, gases, organic compounds or microbiological activity is called _______.

Alloys with nickel content above _________ are highly resistant to Cl SCC. The greatest susceptibility is 8% to 12% nickel.