Important basic concepts in Engineering metallurgy: GATE Mechanical

The present resource contains the important basic concepts in Engineering metallurgy in Mechanical Engineering. Note down each concepts which might help in GATE 2013 Mechanical.

• Delta iron occurs at temperature between 1400 ^oC and 1539 ^oC .
• Gamma iron exists at temperature between 910 ^oC and 1400 °C .
• Ferromagnetic alpha iron exists in temperature range below 723 °C .
• Para-magnetic alpha iron changes to gamma iron at 910 °C.
• Fatigue failure: Fatigue failure occurs when a part is subjected to compressive stress.
• Homogeneous : A body having identical properties all over
• Elastic behavior : If a material recovers its original dimensions, when load is removed.
• A ductile fracture is characterized by appreciable plastic deformation prior to propagation of crack.
• Resilience: The ability of a material to absorb energy when deformed elastically 
• Machining properties of steel can be improved by adding sulphur, lead, phosphorus.
• Eutectoid steel the percentage of carbon is 0.8%.
• A cold chisel is made of high carbon steel.
• An engineer’s hammer is made of forged steel.
• Cyaniding: The process of adding carbon and nitrogen by heat treatment of steel to increase its surface hardness.
• Tensile strength of common varieties of cast iron is in the range 840-500 Mpa.
• In carbon steel casting the percentage of carbon is less than 1.7%.
• Aluminium alloys for pressure die casting must posses considerable fluidity.
• Electro forming is Specially valuable for thin walled parts requiring a high order of accuracy and internal surface finish.
• In power metallurgy the process of heating the cold pressed metal power is called sintering.
• The hardness of steel increases if it contains martensite.
• The presence of sulphur in pig iron makes the casting unsound.
• Compressive strength of grey cast iron in tones per square cm is of the order of 5-7.
• The machinability of steel can be increased by phosphorous, lead and sulphur.
• Steel with 0.8% carbon and 100% pearlite is known as eutectoid steel
• The maximum hardenability of any steel depends on the carbon content.
• In 18-4-1 high speed steel the maximum percentage is of iron.
• In compression, a prism of brittle material will break by shearing along oblique plan.
• Cast-alloy contains nickel and molybdenum.
• Trimming is a process associated with forging.
• Addition of lead and bishmuth to aluminium results in improving machinability
• Foundry crucible is made of graphite.
• Age-hardening is related with duralumin.
• For heavy loads in aircraft bearings the malarial used with lead to reduce the risk of seizure, is silver.
• As compared to steel the tensile strength of wood is generally 1/5.
• Compressive strength of wood is generally more along the grains.
• Superconducting property exist at temperatures below 10 K.
• Weld Decay: The phenomenon of weld decay is associated with stainless steels.
• Bloom: Bloom are obtained by passing hot ingots through the rolling mills and are of size 150 mm x 150mm to 350mm x 350mm.
• A knoop indenter is a diamond group to a pyramdidal from.
• A unit cell that contains nine atoms is known as body centered cubic space lattice.
• The process commonly used for thermo-plastic material is injection moulding.
• The most important element that controls the physical properties of steel is carbon.
• In process annealing process, the hypoeutectoid steel is heated below A₁ line with a view to make steel ductile for cold working.
• The imperfection in the crystal structure of metal is known as dislocation.
• Polyesters belong to the group of thermosetting plastics.
• The effect of alloying zinc to copper is to increase strength and ductility (if added up to 10-30 %.)