Tim's Board

Thank you. Recording now on Moodle. Kind regards, Tim

Thank you. The upper limit is 2.14 wt% C. 4.14 wt.% was a typo. Apologies. Kind regards, Tim

on the answers to the probelm sheet why is hyper eutectoid steel from 0.76 to 4.14 rather than 0.76 to 2.14 wt % C

Thank you. This is an interesting question, without an initially obvious answer (to my mind). Watch this space ... Kind regards, Tim

can galvanic corrosion and de-aeration corrosion occur at the same time? E.g. at the point where two metals meet a crevice may form.

Where can we find the recording of the LOIL?

Thank you. This will be available from Moodle next week. Tim

PS: The sheet was emailed while Moodle was being serviced.

where can I find the problem sheet you mentioned in our final lecture

Thank you. Surface damage in metals can lead to anodes (i. e., corrosion) due to (1) stresses that caused the damage leading to local weakening / breaking of metallic bonds, and (2) pit initiation. I hope this helps. Kind regards, Tim

is the reason to minimise surface damage and minimise stress in the design of the electrode because it can lead to pitting corrosion which will wear away at the material?

could you describe what the graph of stress amplitude vs cycles to failure represents (S-N) and what a fatigue limit is?

Thank you. The y-axis on the lower graph for fatigue in my lecture notes is the amplitude of the sinusoidal stress (sigma-a from the higher graph) for a given mean stress (sigma-m) and wave frequency. The x-axis is the number, N, of fatigue cycles until the material fails. Initially as sigma-a decreases, N increases until a certain sigma-a when the sample appears never to fail. This is the fatigue limit which is common for many steels. For values of sigma-a at or below the fatigue limit the material can be cycled indefinitely. This concept is useful in the selection of materials subjected to fatigue (cyclic) loads. I hope this helps. Kind regards, Tim

Thank you. Dr Eleni Sikou (Unit Manager) will be able to help with this. Previous exam papers may also be useful. I hope this helps. Kind regards, Tim

where can I find practice questions that will be similar to those we'll find in the course work?

Thank you. In materials science, an INTRINSIC property (density, tensile strength, ...) does not depend on how much material is present nor on its form (particles, large pieces, ...) but mainly on the material's internal structure and composition. This compares with an EXTRINSIC or ATTRIBUTIVE property that may depend on the material's external chemical or physical environment or on "human" factors such as the economy. I hope this helps. Kind regards, Tim

Tim Mays' Q&A board connected to his C10232 materials science lectures.

Short, sharp questions please. I will aim to respond quickly, and briefly.

Thanks, Tim Mays

what is the difference between an intrinsic and an attributive property?

Thank you. You are already being exposed to metallurgy in my lectures, but sadly we only have six lectures to cover a massive area so I'm afraid we can't go too wide or deep at this stage. I hope this helps. Kind regards, Tim

Do we learn about metallurgy in this course?