1results about How to "Avoid Nitrogen Problems" patented technology

This invention relates to a steel for automobile engine pistons and its manufacturing method. The chemical composition of the steel, by weight percentage, is: C: 0.41–0.47%, Si: 0.15–0.35%, Mn: 0.70–1.00%, Cr: 1.10–1.40%, P: ≤0.020%, S: 0.015–0.035%, Mo: 0.17–0.27%, Al: 0.010–0.030%, N: 0.0040–0.0060%, with the balance being Fe and unavoidable impurities. The microstructure consists of ferrite and pearlite, with uniform distribution of ferrite and pearlite structures. The geometric center distance between each ferrite and pearlite structure is 15–30 μm. The hot-rolled hardness of the steel is ≤230 HBW, and the banded structure in the steel is ≤1.5 grade. The product features a narrow range of carbon deviation in cross-section, shallow decarburized layer and microcrack depth on the steel surface, low hot-rolled hardness, good banded structure, and high tensile strength after quenching and tempering.