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Question 82

High strength, low allow steels such as A193-B7 bolts and compressor parts are susceptible to hydrogen stress cracking. A193-B7M bolts are susceptible if __________.

    Correct Answer: B

    A193-B7M bolts are susceptible to hydrogen stress cracking if they are overtorqued. Overtorquing introduces tensile stress into the bolt, which can facilitate the accumulation of hydrogen at sites where the surface might be damaged. This tensile stress combined with hydrogen presence leads to hydrogen stress cracking in high-strength low-alloy steels such as those used in A193-B7M bolts.

Discussion
ahmadmmOption: B

ASTM A193-B7M bolts are made of a high-strength, chromium-molybdenum alloy steel. This type of steel is susceptible to hydrogen stress cracking (HSC) when exposed to hydrogen and subjected to tensile stress. Overtorquing can lead to HSC in A193-B7M bolts because it introduces tensile stress into the bolt. The overtorque can also damage the bolt's surface, which can create sites where hydrogen can accumulate. Hydrogen can enter the bolt in a number of ways, including: From the environment, such as from moist air or corrosive liquids From electroplating or other surface treatments From welding or other thermal processes