Malleable cast irons — which types show steel-like properties? Select the option that correctly identifies the malleable irons whose mechanical behavior (ductility and bendability) resembles that of low-carbon steel.

Introduction / Context:
Malleable cast irons are obtained by heat treating white iron to convert brittle carbides into temper carbon, yielding improved ductility and toughness. Some malleable irons can exhibit properties that approach those of mild steel, making them suitable for forgings-like applications and components requiring bending without fracture.

Given Data / Assumptions:

• Blackheart malleable iron: produced by annealing in a neutral environment, leading to ferritic or ferritic-pearlitic matrices with temper carbon nodules.
• Whiteheart malleable iron: produced by decarburizing anneal in oxidizing conditions, yielding a predominantly ferritic rim with ductility.

Concept / Approach:
Both blackheart and whiteheart variants replace brittle cementite with temper carbon in a ductile matrix, substantially improving elongation and bendability compared with as-cast gray or white irons. While they do not match the full work-hardening capacity of low-carbon steel, their stress-strain response and formability are much closer to steel than ordinary cast irons, especially in thin sections.

Step-by-Step Solution:

Verification / Alternative check:
Tensile tests show significant elongation (for example, 5–15% depending on grade) in malleable irons; bend tests without cracking further confirm steel-like characteristics relative to gray/white iron.

Why Other Options Are Wrong:

• Chilled white cast iron only: this is very hard and brittle due to massive carbides; it is not steel-like in ductility.
• None of these: contradicts well-known performance of malleable irons.

Common Pitfalls:
Confusing malleable iron with nodular (ductile) iron; both improve ductility but by different graphite morphologies and processing routes.

Final Answer: