SEDL / STP / STP792-EB / STP31771S

Effect of Microstructure on Sulfide-Stress-Cracking Resistance of High-Strength Casing Steels

Sponseller, DL
Staff metallurgist and senior research associate, Climax Molybdenum Company of Michigan, Ann Arbor, Mich.

Garber, R
Staff metallurgist and senior research associate, Climax Molybdenum Company of Michigan, Ann Arbor, Mich.

Straatmann, JA
Manager, Oil Industry Development, Climax Molybdenum Co., Pittsburgh, Pa.

Pages: 33    Published: Jan 1983

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Abstract

The effect of microstructure on the sulfide-stress-cracking (SSC) resistance of developmental high-strength Cr-Mo and Mn-Mo casing steels has been evaluated. Results obtained in many investigations, some previously published and some new, conducted at this laboratory over the past decade are presented and discussed in the light of published results on hydrogen-assisted fracture of steels from other laboratories. The processing variables examined include hot working, austenitizing conditions, quench rate, tempering temperature, and cooling rate from the tempering temperature. An analysis of the data reveals that SSC resistance is aided by refinement of the austenite grain size, by the achievement of a fully martensitic microstructure during hardening, by increasing the tempering temperature, and by water quenching after tempering. The SSC resistance is degraded severely by tempering just above the lower critical (Ac¹) temperature and then water quenching. Cast structures are comparable to wrought structures in SSC resistance.