| 摘要 |
<p num="1">A low-alloy steel containing, by weight percent, C 0.03-0.13%, Mn 0.90-1.80%, Si '||to_char('&')||'lt;= 0.40%, P '||to_char('&')||'lt;= 0.020%, S '||to_char('&')||'lt;= 0.005%, Ni 0.10- 1.00%, Cr 0.20-1 .20%, Mo 0.15-0.80%, Ca '||to_char('&')||'lt;= 0.040%, V '||to_char('&')||'lt;= 0.10%, Nb'||to_char('&')||'lt;= 0.040%, Ti '||to_char('&')||'lt; 0.020% and N '||to_char('&')||'lt;= 0.01 1 % for making high-strength, weldable steel seamless pipe, characterized in that the microstructure of the alloy steel is a mixture of bainite and martensite and the yield stress is at least 621 MPa (90 Ksi). It is a second object of the present invention to provide a high- strength, weldable steel seamless pipe, comprising an alloy steel containing, by weight percent, C 0.03-0.13%, Mn 0.90-1.80%, Si '||to_char('&')||'lt; 0.40%, P '||to_char('&')||'lt;= 0.020%, S '||to_char('&')||'lt; 0.005%, Ni 0.10-1.00%, Cr 0.20-1.20%, Mo 0.15-0.80% , Ca '||to_char('&')||'lt;= 0.040%, V '||to_char('&')||'lt;; '||to_char('&')||'lt; 0.10%, Nb '||to_char('&')||'lt; 0.040%, Ti '||to_char('&')||'lt; 0.020% and N '||to_char('&')||'lt; 0.01 1 % also characterized in that the microstructure of the alloy steel is predominantly martensite and the yield stress is at least 690 MPa (100 ksi).
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