21-40 Flashcards
What is the fatigue limit?
● Maximum stress amplitude below which the material never fails, no matter how large the number of cycles is.
Fatigue is highly affected by the surface quality. Name one solution to how fatigue life can be increased by surface treatment:
● Shot peening
● Case hardening
Name a surface treatment of Al-alloys that is detrimental to fatigue life:
● sulphuric acid anodizing
List two types of molecular structures of polymers:
● Linear polymers
● Branched polymers
● Cross-linked polymers
● Network polymers
What is the glass transition temperature?
● Glass transition is when the polymer becomes a rigid solid on cooling, while retaining the
disordered molecular structure characteristic to liquids.
● The glass transition temperature is between 0.5 and 0.8 of the melting temperature.
The material X10CrNi18-10 is:
● an alloyed steel
The material 1.7734.6 designates:
● hardened and tempered condition.
Which alloying element increases strength?
● Carbon (C)
Which alloying element increases corrosion resistance:
● Nb (Niobium)
● Cr (Chromium)
● Ti (Titanium)
What does the term Nb or Ti stabilize mean in corrosion-resistant materials/welding filler materials:
● A form of intergranular corrosion is weld decay occurs when galvanic corrosion begins from heating the material too long due to welding or improper heat treatment.
● Nb & Ti can be added to form carbides faster than Cr and preventing Cr carbide precipitation and subsequent corrosion.
The material EN AC-51300F is:
● Cast aluminium alloy
1.7734.6 designates:
● Hardened and tempered condition
What is the advantage of Al-Li alloys when compared to Li-free alloys:
● Reduces alloy density
● Increases modulus
● Higher stiffness
● Excellent fatigue and cryogenic toughness properties
● Superior fatigue crack growth resistance
Do Al-alloys have a fatigue limit?
No.
What type of material is preferably used for lightweight complex castings?
● Magnesium alloys
