Knife Line Attack on Stabilized Austenitic Stainless Steel (ASS): A Welding Engineer's Perspective Introduction As a welding engineer, it is crucial to understand the various challenges associated with different types of steels and their welding processes. One such challenge is the occurrence of knife line attack on stabilized Austenitic Stainless Steel (ASS). In this blog, we will delve into the causes, consequences, and possible remedies for this issue. Understanding Knife Line Attack Knife line attack refers to a very narrow band or line that forms in an area adjacent to the fusion boundary during the welding process. This phenomenon specifically occurs in stabilized ASS. The affected area experiences a thermal cycle close to the fusion boundary, where temperatures rise significantly above the solidus temperature. Causes of Knife Line Attack Knife line attack in stabilized ASS is primarily attributed to the behavior of titanium (Ti) and niobium (Nb) carbides. Normall...
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Sensitization in austenitic stainless steel occurs when the material is exposed to temperatures within the sensitization range for an extended period. This can happen during welding or heat treatment processes. The formation of chromium carbides at the grain boundaries due to the combination of carbon and chromium atoms leads to a depletion of chromium in the surrounding regions. This depletion creates a chromium-depleted zone along the grain boundaries, making the steel susceptible to intergranular corrosion. The implications of sensitization in welded structures are significant. Intergranular corrosion weakens the material and can result in localized failures and reduced structural integrity. In critical applications where corrosion resistance is vital, such as in the chemical, petrochemical, and food processing industries, the avoidance of sensitization is crucial to maintain the reliability and longevity of welded components. To mitigate sensitization, w...
ESTIMATION OF WELDING COST: Welding procedure specification provide important data needed to calculate the cost of weld. Typical variables that includes 1)Cycle time, 2)Electrode or filler wire Size, 3)Type Electrode, 4)Deposition efficiency, 5)Type of joint, 6)Type of weld, 7)Weld size, 8)Type of shielding, 9) Shielding gas, 10)Flow rate, 11)Flux consumption ratio, 12)Welding current Arc, voltage,13) Power source efficiency, 14)Welding time, 15)Operator factor, 16) Labor rates, 17) Overhead rate, 18) Filler metal cost, 19) Shielding gas cost , 20) Setup costs Inspection all these cost determines the cost of welding. Material estimate: Amount of filler material deposited can be basis of all the material cost apart from filler material other cost like process specific variables. Labour hours can be calculated from accurate list of materials and summary of operation required for production. Bill of materials When the material estimate is prepared welding pr...
Total Welding Management Reducing the non-productive hours in each of the five welding Do’s REDUCE WELD METAL VOLUME: ü One of the most common problems is the mindset that the “bigger the weld volume, better the weld “which is fundamentally wrong. ü Over welding adds to the labour cost and causes shrinkage and distortion. ü Correct specification of the child parts should be ensured to ensure the proper fit-up and weld specification. ü Reduced weld size and weld joint openings will result in less weld metal volume and decreased shrinkage and distortion. ü Awareness to be provided to the welders to prevent welding them in higher sizes than required. REDUC...
EFFECTS OF BASIC ALLOYING ELEMENTS IN STEEL The term alloy means the metallic substance which contains two or more elements, as we know steel is the alloy of Iron ( Fe). The presence of certain elements may affect the property of the steel. There are certain elements that are added to improve the existing property of the steel while on another side certain elements are added to mitigate the effect caused by impurities present. The basic impurities present in the steel right from the beginning are Carbon, Sulphur, Phosphorus, Silicon, and Magnesium, and the effects are given below in the picture.