公开(公告)号：EP3173764A4

公开(公告)日：2017-07-26

申请号：EP15824727

申请日：2015-07-17

Applicant: JFE STEEL CORP

Inventor： YUGA MASAO ,  ISHIGURO YASUHIDE ,  FUJIMURA KAZUKI ,  OKATSU MITSUHIRO ,  SUGANO YOSHIYUKI

IPC: G01N3/08 ,  C22C38/00 ,  C22C38/50 ,  G01N17/00

CPC classification number: G01N17/006 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  G01N3/08 ,  G01N17/00

Abstract: When the resistance to sulfide stress corrosion cracking is evaluated by applying a constant load stress à (MPa) to a round bar tensile test specimen immersed in a test solution and checking whether failure occurs before a particular time passes, the round bar tensile test specimen including a parallel section, a shoulder section, and a grip section is used. In the round bar tensile test specimen, the shoulder section is formed by a curve having two or more radii of curvature, a radius of curvature R1 (mm) of a portion adjacent to the parallel section is 15 mm or more and satisfies (0.22à - 119) ‰¤ R1 ‰¤ 100, a length X1 (mm) of a portion of the curve having the radius of curvature R1 in a longitudinal direction of the test specimen satisfies X1 ‰¥ ˆš{(r/8) × (R1 - r 2 /4)} (r: radius (mm) of the round bar tensile test specimen in the parallel section), and the radius of curvature R1 is larger than other radii of curvature. Thus, even when the steel is a high-strength steel having a yield strength of 758 MPa or higher, the occurrence of the failure in the shoulder section is suppressed, and the resistance to sulfide stress corrosion cracking can be properly evaluated.

Abstract translation: 当通过对浸入试验溶液中的圆棒拉伸试验样品施加恒定负荷应力（MPa）并且在特定时间过后检查是否发生破坏来评价耐硫化物应力腐蚀开裂性能时，圆棒拉伸试验样品包括 平行部分，肩部部分和把手部分。 在圆棒拉伸试验片中，肩部由具有两个以上曲率半径的曲线形成，与平行部相邻的部分的曲率半径R1（mm）为15mm以上，满足（0.22× -119）≤R1≤100，曲率半径R1在试验片长度方向上的曲率部分的长度X1（mm）满足下式：（R1）×（R1 - r 2/4）}（r：平行截面中的圆棒拉伸试验片的半径（mm）），曲率半径R1大于其他曲率半径。 因此，即使在钢为屈服强度为758MPa以上的高强度钢的情况下，也能够抑制肩部的失效发生，能够适当地评价耐硫化物应力腐蚀开裂性。