Pipeline Fabrication

Question 1

How much silicon content is required to fully kill steel?

Answer 1

A silicon content >0.1% indicates a fully killed steel

Question 2

Define Ferrite

Answer 2

A form of pure iron with a body-centred cubic crystal structure, occurring in low-carbon steel

Question 3

Define Pearlite

Answer 3

A finely laminated mixture of ferrite and cementite present in cast iron and steel, formed by the cooling of austenite.

Question 4

What is the typical linepipe composition?

Answer 4

0.2% carbon

Question 5

Define solid solution hardening

Answer 5

Solid solution strengthening is a type of alloying that can be used to improve the strength of a pure metal. The technique works by adding atoms of one element (the alloying element) to the crystalline lattice of another element (the base metal), forming a solid solution.

Question 6

Define precipitation hardening

Answer 6

Precipitation hardening is a method that makes use of heat application to a pliable material, like metal alloy, to make it tougher. This technique gives strength to alloys by hardening them and adding fine, solid impurities known as precipitates. This can halt dislocation movements within the structure of its crystal lattice.

Question 7

Accelerated Cooling

Answer 7

Enhances ferrite grain refinement and prevents pearlite formation

Question 8

Strain hardening capacity

Answer 8

Determined by a strain-hardening exponent – measure
of the ability of a material to strain harden. The larger
its magnitude the greater the strain hardening for a
given amount of plastic strain. Generally characterised for pipeline steels by the Yield/Tensile ratio and considered to be too high for strain based design.

Question 9

Tensile strain capacity

Answer 9

Tensile property variation along the pipe and through thickness. Can have higher consequences in high strength steels with lower strain hardening capacity.