Answer / Vikas Kumar Agarwal

Poor paint finishes on aluminum castings can be caused by several factors: 1) Surface preparation: Inadequate cleaning and surface treatment before painting can leave contaminants that interfere with adhesion. 2) Moisture content: Aluminum is highly reactive with moisture, which can cause hydrogen gas evolution during welding or casting processes, leading to porosity in the castings and affecting paint adherence. 3) Alloy composition: Different aluminum alloys have varying surface properties that may affect paint adhesion. For example, alloys containing magnesium or silicon can form oxides that are difficult to paint on. 4) Galvanic corrosion: If the aluminum casting is in contact with dissimilar metals, galvanic corrosion can occur, causing localized corrosion and affecting paint adherence.

What is the metallurgy use? What is the casting and forging?

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Define what is the difference between diagrams of it and ct in heat treatment of steels?

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The requirement for ASTM A217 Gr. WC9 castings for valves components like Body and Bonnet were Normalising at 920+/- 20 Deg. C and Tempring 780+/- 20 Deg. C The specification calls furnace shall be calibtated within +/-14 deg. C The Heat Chart shows minimum temperature for normalising 900 to 920 Deg. C, but maximum temperature 960-990 Deg. C Tempering 780+/-20 Deg. C is within limits and accepted. Casting having integral test bars, heat trated along with castings passed in chemical znalysis and mechanical properties. Since normalising maximum temperature is not meeting specification, where castings can be salvaged or renormalised and retempered to meet specification. Whether it will have affect on remechanical properties testing

1 Answers   Leader Valves,

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For the same part, it is possible to Specify the two different type of Hardness with same scall(EX-Quenching and tempering==>450 to 500HV30 & Hardening and Austempering 330- 380HV30)

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What happens when the mercury of a thermometer spills over the gold ring?

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What are the componentsof SCS14 ?

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When austenitized, carbon steel is quenched, why is the bcc crystal elongated into a body-centered tetragonal crystal structure?

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Why same casting has different hardness and machine-ability properties?

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What type of grinding is used for harder materials?

1 Answers   NIC,

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what is the difference beteeen Annealing and stress releaving

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sir.I am OBC candidate,recieved scholarship/freeship during academic year 2011-2012,2012-2013(my yearly income was below 4.5 lakh).my yearly income during academic year 2013-2014 was above 4.5 lakh.should I get scholarship/freeship in academic year 2013-2014 ?

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Will aluminum alloy like 380 or 356 settle? Meaning while in “liquid form” above melting point will the heavier elements like copper, fe, silicon, zinc etc. Settle to the bottom of the liquid/molten aluminum after a period.

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