SAW Metallurgy & Weld Quality Inspection 5

Question 1

What effect does increasing heat input have on the coarse-grained HAZ toughness of low-alloy steel?

Accepted Answer

It reduces toughness by promoting grain growth and unfavorable microstructures

Answer

Higher heat input raises the peak temperature and slows cooling, allowing excessive austenite grain growth in the CGHAZ, resulting in coarser, tougher-degrading microstructures.

Question 2

According to AWS D1.1, what is the maximum permitted depth of individual surface porosity for a CJP groove weld visible on the surface?

Accepted Answer

3/32 in.

Answer

AWS D1.1 limits visible individual surface porosity to a maximum diameter of 3/32 in. (2.4 mm) with frequency and cluster restrictions.

Question 3

What is the primary metallurgical reason for preheating high-carbon steel before SAW?

Accepted Answer

To slow the cooling rate and prevent formation of brittle martensite in the HAZ

Answer

Preheat raises the starting temperature of the base metal, slowing the post-weld cooling rate and suppressing martensite formation in the high-carbon HAZ.

Question 4

A magnetic particle test (MT) on a SAW weld reveals a linear indication at the weld toe. This most likely indicates:

Accepted Answer

A surface or near-surface crack

Answer

MT reveals surface and slightly subsurface discontinuities with a magnetic field; a linear indication at the weld toe is characteristic of a toe crack.

Question 5

In fracture mechanics, the term CTOD (Crack Tip Opening Displacement) test is used to:

Accepted Answer

Quantify the fracture toughness of a weld or HAZ at various temperatures

Answer

CTOD testing measures the displacement at a crack tip at the point of fracture or plastic instability, giving a direct measure of fracture toughness applicable to weld quality.

(SAW) Submerged Arc Welding Certification Practice Test

(SAW) Submerged Arc Welding Certification Practice Test

SAW Metallurgy & Weld Quality Inspection 5