Hadfield (austenitic manganese) steel: Approximate manganese content used for crusher jaws and impact-resistant parts is __________ %.

Introduction / Context:
Austenitic manganese steel (Hadfield steel) is renowned for exceptional work-hardening and toughness, making it ideal for high-impact wear parts like crusher jaws, hammers, and railway crossings.

Given Data / Assumptions:

• Typical alloy contains high Mn with carbon around 1.0–1.4% C.
• Used where impact and gouging wear dominate.
• Service relies on strain-induced hardening.

Concept / Approach:
At about 12–14% Mn, the steel retains an austenitic matrix at room temperature. Under impact, it work-hardens at the surface while maintaining a tough core, delivering a unique combination of wear resistance and resilience.

Step-by-Step Solution:
Recall nominal composition: ~1.2% C and 12–14% Mn.Relate composition to property: high Mn stabilizes austenite and promotes work-hardening.Select the option 12–14% as standard content for crusher jaws.

Verification / Alternative check:
Standards and datasheets (e.g., ASTM A128 grades) specify Mn in this range for Hadfield steel used in impact wear components.

Why Other Options Are Wrong:
Lower Mn levels (under ~10%) do not provide the fully austenitic, work-hardening behavior; they form pearlite or martensite and lose the hallmark properties.

Common Pitfalls:
Heat treatment and service temperature can alter performance; water quenching after solutionizing is typical to retain austenite prior to service work-hardening.

Final Answer:
12–14