Metallurgy Engineering Interview Questions and Answers
Question - 31 : - What Is Meant By Hardening Ability Of Metals?
Answer - 31 : -
It is the ability of a metal to become hard (and inevitably brittle) under a given cooling rate. Therefore, the higher the hardenability of an alloy, the lower the cooling rate required to harden the metal. We have more heard about the hardenability in steels rather than other alloys. This is because in steels, there are different phases which can appear subject to the applied cooling rate below the critical temperature (the eutectoid temperature) as well as the alloying elements present in that grade of steel. Most of alloying elements in steel improve its hardenability by decreasing the critical cooling rate required to obtain the hardest possible phase i.e. martensite.
Question - 32 : - What Metal Cord Transfers Electricity, And How Can I Tell?
Answer - 32 : -
As far as I am concerned, copper is known as a good and cheap conductor of electricity. Although there are some other elements, such as silver, with higher conductivities copper is preferred due to its being rather cheap. Sometimes because of weight considerations, aluminum is also used even though it has a lower conductivity compared to copper.
Question - 33 : - Is There A Possibility Of Inducing Stress Cracking In An Insulated Stainless Road Tanker Vessel (20 Tonne Capacity) If The Vessel Is Subject To Rapid Filling (10 Tonne /hr) With Liquid Methane (-160 C) Assuming The Vessel Is At Ambient. If So, Where Could I Obtain Suggested Cooling Rates?
Answer - 33 : -
Assuming a twohour load time, insulation in good condition and steel in good condition with no existing stress cracks at the welds, and a "precool" period prior to rapid loading, the unit should hold up OK.
If you start with an ambient unit, and you have an inrush of liquid methane, the initial boiling of the methane in the unit will be very vigorous until the inner surfaces are cooled down. This violent boiling will result in liquid being ejected from the unit if care is not taken, and could result in damage to the insulation and liner. It would be best to load a small amount of the liquid methane into the unit and let it boil away, collecting the fumes and recompressing if possible, thereby cooling the inner components of the unit. This will lessen the initial thermal shock and reduce the likelihood of stress cracking.
Question - 34 : - What Are Metallurgical Microscopes?
Answer - 34 : -
A metallurgical microscope is an inverted scope with light sources designed for magnifying structures of metallographically prepared specimens. The magnification is no different from most normal upright scopes. Companies including Nikon and Olympus produce the scopes and you will be able to find a plethra of information about the scopes on their websites. I would also consider contacting their sales reps to ask specific technical questions about the scopes.
Question - 35 : - What Is The Minimum Temperature For Stress Relieving Of Astm A 519 Gr.4130 Material And Please Tell Us Where We Can &nd The Location?
Answer - 35 : -
Stress relieving of alloy steels (like 4130) has no temperature outlined in the spec of the material.
However, it is common practice to stress relieve 4130 between 1050 and 1200 F. This is high enough to relieve the stress with out being hot enough that the material has an austenitic phase change, which occurs around 1350 F.
Question - 36 : - Is There Any Way Through Hardening And Anodizing Some Type Of Aluminum, It Could Be As Hard As Steel? I Have Hardened Steel Rollers That Run Up And Down On A Ramp Along With Spring Pressure. Alternatively, If You Are Familiar With Snowmobiles, The Rollers Run On The Helix On The Secondary Clutch?
Answer - 36 : -
Aluminum, while it is incredible for some applications due to it being lightweight, is a very soft and weak metal. There really is not any way to get it any where near the hardness of steel. What people are doing for applications requiring lightweight, but strong materials is going with some new age alloys, mostly consisting of titanium and nickel.
Question - 37 : - When Using Mercury To Recover Very, Fine Gold From Ore, What Is The Best Way To Separate The Gold Laden Mercury From The Ore?
Answer - 37 : -
A centrifugal system would certainly separate the mercury assuming you could maintain a fluidized bed and that there were not large differences in the sizes of the particles in the slurry. Depending on the volume involved, a vibratory table might be better. There are many other methods, but I would need to know the relative size / volume / solidliquid ratio information in order to make a useful recommendation. You need to take special precautions in any case to preclude the release of mercury into the environment.
Question - 38 : - Is It Possible To Use Metallurgical Inverted Microscope To Other Designation?
Answer - 38 : -
A microscope is a microscope for most purposes. First, make sure the light source on the scope is useful in seeing whatever it is you want to see. Certain items are seen well in certain lights. The second thing, as I am sure you have already realized, is that you will have a tough time determining where on the sample you are looking, as it is up side down. For this reason, I even prefer a non-inverted scope even for metallurgical tasks. In summary, if you are ok with the sample being upside down, and the light source is sufficient, there is no reason it will not work to the magnification that scope is specified.
Question - 39 : - Why Is It So Hard To Find Literature On The Wear Resistance Of Titanium?
Answer - 39 : -
Titanium in elemental form is so soft it does not even register on a Rockwell C scale. With that being said, I would guarantee that you are using a titanium alloy of some type, most likely a TitaniumAluminumVanadium alloy. These types of alloys can be processed to hardness in the low 40's HRC. In terms of concentrating on wear resistance, hardness is what you are going to want to focus on. The mechanical properties for various titanium alloys.
Question - 40 : - How To Calculate Heat Affected Zone In Weld?
Answer - 40 : -
Heat affected zone is measured regarding the microstructure changes in the weld. For example in steels, this is the area around the weld zone, which has undergone a transformation. In other words, this is the area, which had been austenitized. For calculating the HAZ after welding, for steels, it is better to macroetech the section of the weld HAZ can be easily recognized by the contrast it makes with the base metal and the weld metal.