SAW Flux Types & Wire Selection 3

Question 1

The Basicity Index (BI) of a SAW flux is primarily used by welding engineers to predict:

Accepted Answer

Diffusible hydrogen potential and expected weld metal mechanical properties

Answer

Higher BI values (>1.5) correlate with lower diffusible hydrogen levels and improved weld metal toughness, making BI a key flux selection criterion for critical structural applications.

Question 2

A SAW flux with a Basicity Index (BI) greater than 1.5 is classified as:

Accepted Answer

Basic (high-basicity) flux

Answer

Fluxes with BI > 1.5 are classified as basic or high-basicity and generally produce lower diffusible hydrogen and better low-temperature toughness compared to acidic (BI < 1.0) or neutral fluxes.

Question 3

What happens when SAW flux layer depth is excessive (too deep)?

Accepted Answer

Gases are trapped, causing a rough or convex bead surface and possible pinhole porosity

Answer

Excessive flux depth prevents arc gases from escaping freely, resulting in back-pressure that produces a rough, humped bead surface and can cause pinhole or wormhole porosity in the deposit.

Question 4

Silicon and manganese transfer from an active SAW flux to the weld metal is significant because it directly affects:

Accepted Answer

Weld metal strength, hardness, and deoxidation efficiency

Answer

Si and Mn are primary deoxidizers and strengtheners; their transfer from active fluxes increases with arc voltage, altering weld metal tensile strength, hardness, and slag viscosity.

Question 5

When recovering and recycling used SAW flux, which contamination concern is most critical to weld quality?

Accepted Answer

Metal fines, slag particles, and moisture that can cause porosity, inclusions, and hydrogen cracking

Answer

Recycled flux must be thoroughly screened to remove slag chips, metallic fines from spatter, and absorbed moisture; each of these contaminants introduces specific weld defects in subsequent runs.

(SAW) Submerged Arc Welding Certification Practice Test

(SAW) Submerged Arc Welding Certification Practice Test

SAW Flux Types & Wire Selection 3