CSWIP 3.1: Question with Answer and Explanation – Part 17

CSWIP 3.1 QUESTION AND ANSWER SERIES

1) Austenitic stainless steels are not susceptible to HICC becausse:

a.	They are non-magnetic
b.	They are stainless and contain chromium
c. ( asnwer )	They don’t harden during heating and cooling
d.	They are highly ductile

HICC is Hydrogen Induced Cold Cracking

Susceptible Microstructure: Hardness Greater than 400HV Vickers (Martensite)

300 Series austenitic stainless steel has austenite as its primary phase (face centered cubic crystal). These are alloys containing chromium and nickel, and sometimes molybdenum and nitrogen, structured around the Type 302 composition of iron, 18% chromium, and 8% nickel. 200 Series austenitic stainless steels replace the majority of their nickel content with manganese to reduce cost. Austenitic steels are not hardenable by heat treatment.

2) The higher the alloy content of steels:

a.	The lower the tendency for HICC to occur
b. ( answer )	The higher the tendency for HICC to occur
c.	High alloy steels do not influence HICC susceptible
d.	None of the above

3) Which one of these statements is true concerning solidification cracking?

a.	Only occurs in MMA welding
b. ( answer )	Increased depth to width ratio will increase stress
c.	Never occurs in MIG/MAG welding
d.	All of the above

Solidification Cracking (hot crack) can occur when:

-Weld metal has a high carbon or impurity (sulphur) content

-The depth-to-width ratio of the solidifying weld bead is large (deep & narrow)

4) A solidification crack normally occurs where?

a.	Through the HAZ
b. (answer)	Longitudinal through the weld centre line
c.	Transverse through the weld
d.	Can occur anywhere

5) Weld decay is caused by the formation of a compound with carbon. The other element in this compound is:

a.	Manganese
b.	Sulphur
c. (answer)	Chromium
d.	Nickel

Occurs when:

An area in the HAZ has been sensitised by the formation of chromium carbides. This area is in the form of a line running parallel to and on both sides of the weld. This depletion of chromium will leave the effected grains low in chromium oxide which is what produces the corrosion resisting effect of stainless steels. If left untreated corrosion and failure will be rapid.

6) The directions of shrinkage in a welded joint are:

a.	Transverse and diagonal
b.	Transverse, short transverse and conical
c. (answer)	Transverse, short transverse and longitudinal
d.	Angular, diagonal and transgranular

7) In a single pass weld, the width of the zone in which longitudinal residual stresses are …

a.	Independent of the weld width
b.	Narrower than the weld metal
c.	The same width as the weld metal
d. ( answer )	Wider than the weld metal and the heat affected zone

8) What does the term “back-step” refer to during welding?

a.	A QA term referring to inspection points
b.	Use of step wedges on the root of the joint
c.	Use of step wedges for radiography
d. (answer)	A weld run sequence