What is the material of 4142 round bar 4142 steel plate?

Introduction to 4142 alloy steel:
4142 steel is an ultra-high-strength steel with high strength and toughness, good hardenability, no obvious temper brittleness, high fatigue limit, multiple impact resistance after quenching and tempering, and good low-temperature impact toughness. This steel is suitable for manufacturing large and medium-sized plastic molds that require a certain strength and toughness. Usually, surface quenching after quenching and tempering is used as a heat treatment solution.

4142 alloy steel chemical composition:
Carbon C: 0.40～0.45%
Silicon Si: 0.15～0.35%
Manganese Mn: 0.75～1.00%
Sulfur S: ≤0.040%
Phosphorus P: ≤0.035%
Chromium Cr: 0.80～1.10%
Molybdenum Mo: 0.15～0.25%