Materials Science and Engineering A 385 (2004) 212–219 Stress corrosion cracking of stainless steel used in drill collars N.A. Mariano a,∗ , D. Spinelli b a Technologic and Scientific Academic Unit, University S˜ ao Francisco, Itatiba, SP 13251-900, Brazil b Engineering School of S˜ ao Carlos, University of S˜ ao Paulo, S˜ ao Carlos, SP 13566-590, Brazil Received 28 January 2004; received in revised form 7 June 2004 Abstract The present work, studies the stress corrosion cracking behavior in austenitic Fe–Cr–Mn–N stainless steel, in as received, solubilized and sensitized conditions, submitted to several chlorides environments. To evaluate the stress corrosion cracking susceptibility, double cantilever beam specimens, fatigue precracked, side grooved and wedge loaded were used. The environments employed were boiling solution of 45 wt.% of MgCl 2 at 154 ◦ C and synthetic marine environment at ambient and boiling temperature. The susceptibility to stress corrosion cracking has been evaluated in terms of the corrosion stress intensity limit factor, K ISCC , applying the fracture-mechanics concept. The results showed that only the specimens in the as received and sensitized conditions, were susceptible to the stress corrosion cracking effect in the boiling solution of 45 wt.% of MgCl 2 at 154 ◦ C, and mean values of the stress corrosion intensity limit factor, K ISCC , of 15 MPa √ m and 7.8 MPa √ m, respectively. © 2004 Elsevier B.V. All rights reserved. Keywords: Stress corrosion cracking; Chloride; Austenitic stainless steel 1. Introduction The scarcity of nickel during World War II led to the development of new stainless steel alloys with nickel con- tent lower than normal. The first partial substitute of nickel in the steels of the austenitic group was manganese. Since then, studies focusing on the austenitic stainless steels of the iron–chromium–manganese–nitrogen system have inten- sified [1,2]. Several free nickel alloys have been developed as substi- tutes for the conventional austenitic stainless steel used in cryogenic environments and services and in applications that require good corrosion resistance. These developments have resulted in the partial replacement of nickel and the reduc- tion of chromium from 18 to 13 wt.%, with the addition of manganese and nitrogen. The manganese content of around 11 wt.% increases the solubility of nitrogen in solution, reducing the nickel content ∗ Corresponding author. E-mail address: neide.mariano@saofrancisco.edu.br (N.A. Mariano). required, but it does not provide the same corrosion resis- tance effects as nickel and chromium; therefore, a minimum amount of nickel must remain in the alloy’s composition (usu- ally less than 5.0 wt.%) [3]. The measuring while drilling (MWD) system was devel- oped to determine the parameters of oil drilling, such as the azimuth, which guides the tool’s face in deep drilling, where service conditions require materials that are nonmagnetic and resistant to both static and dynamic loads, such as corrosive environments [4,5]. Because of their excellent combination of mechanical properties and corrosion resistance, the stainless steels of the Fe–Cr–Mn–N system are used in the manufacture of drill collars, mainly for offshore platforms [6]. Therefore, it is necessary to understand these steels’ behavior in the pres- ence of corrosion caused by their interaction with corrosive environments and the mechanical loads to which they are subjected. Stress corrosion cracking (SCC) is a failure process that occurs because of the simultaneous presence of tensile stress, an environment and a susceptible material. The susceptibil- 0921-5093/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2004.06.041