Material Selection & Properties Flashcards

Which carbon content range classifies steel as 'high-carbon steel'?

Answer: 0.60% to 1.00%

High-carbon steel contains approximately 0.60% to 1.00% carbon, making it harder but more brittle and difficult to weld.

What does the term 'hardenability' refer to in welding metallurgy?

Answer: The ability of steel to form martensite upon rapid cooling

Hardenability describes how readily steel forms martensite through the depth of a section when quenched, which directly impacts weld HAZ properties.

Which austenitic stainless steel grade is most susceptible to sensitization during welding?

Answer: 304

Type 304 stainless steel is susceptible to sensitization because it lacks stabilizers or low carbon content to prevent chromium carbide precipitation.

What is the primary purpose of adding niobium (columbium) to stainless steel?

Answer: Stabilize against intergranular corrosion during welding

Niobium acts as a stabilizer by preferentially combining with carbon, preventing chromium carbide precipitation and sensitization at grain boundaries.

When welding dissimilar metals with different coefficients of thermal expansion, what primary problem can occur?

Answer: Residual stress and distortion upon cooling

Different thermal expansion rates cause unequal contraction upon cooling, generating residual stresses that can lead to cracking or distortion.

Which property describes a material's ability to be drawn into wire without fracturing?

Answer: Ductility

Ductility is the ability of a material to deform plastically under tensile stress, which is measured by elongation and reduction in area.

What is the effect of sulfur content above 0.05% in steel on weldability?

Answer: Promotes hot cracking in the weld and HAZ

Excess sulfur forms low-melting iron sulfide compounds at grain boundaries, causing hot cracking (solidification cracking) during welding.