SPRING STEEL HAVING SUPERIOR FATIGUE LIFE, AND MANUFACTURING METHOD FOR SAME

    公开(公告)号:US20210164078A1

    公开(公告)日:2021-06-03

    申请号:US17261457

    申请日:2019-07-19

    摘要: A spring steel having a superior fatigue life, and a manufacturing method for the same. The chemical components thereof are as follows in weight percentage: C: 0.52-0.62%, Si: 1.20-1.45%, Mn: 0.25-0.75%, Cr: 0.30-0.80%, V: 0.01-0.15%, Nb: 0.001-0.05%, N: 0.001-0.009%, O: 0.0005-0.0040%, P: ≤0.015%, S: ≤0.015%, and Al: ≤0.0045%, with the remainder being Fe and incidental impurities, wherein the following condition is also met 0.02≤(2Nb+V)/(20N+C)≤0.40. The spring steel of the present invention has a microstructure of tempered troostite+tempered sorbite, a prior austenite grain size less than 80 um, a size of alloy nitride and carbide precipitates being 5-60 nm, and a maximum width of single-grain inclusions being less than 30 pm. The spring steel has a handling strength greater than 2020 MPa, superior ductility and toughness (the reduction of area≥40%), and a fatigue life≥800,000 times, thereby meeting application requirements of high-stress springs in industries, such as automobiles, machinery, and the like.

    CONTINUOUS-CURVATURE CONVEX ROLL FOR CONTINUOUSLY CASTING BLOOM, AND MANUFACTURING METHOD THEREFOR

    公开(公告)号:US20210316358A1

    公开(公告)日:2021-10-14

    申请号:US17271094

    申请日:2019-08-16

    IPC分类号: B22D11/128 B22D11/12

    摘要: Disclosed are a continuous-curvature convex roll for continuously casting a bloom, and a manufacturing method therefore, belonging to the field of metal casting. An outer contour curve of a working portion of a body of the continuous-curvature convex roll consists of a first straight-line segment (AB), a first transition curve segment (BC), a intermediate straight-line segment (CD), a second transition curve segment (DE) and a second straight-line segment (EF). The first transition curve segment (BC), the first straight-line segment (AB), and the intermediate straight-line segment (CD) have continuous first-order derivatives, continuous second-order derivatives, and continuous curvatures, thus forming a first transition curve with a continuous curvature. The first transition curve segment (BC) and the second transition curve segment (DE) are mirror-symmetrical. The continuous-curvature convex roll manufactured according to the technical solution can uniformly deform a blank cast in a deformation area, thereby reducing cracks. The transition curve of the convex roll can be reduced, thereby being capable of further reducing a rolling pressure and the withdrawal resistance. The present invention can be widely used in the field of metal casting.