SSRT testing

The Small Scale Shock Reactivity Test (SSRT test) follows a similar principle. In this test, the explosive under investigation ( sample in Fig 7.23) is initiated by a commercial detonator and the depth in a solid aluminum block is measured for example by filling it with fine sand (Si02) and correlating the dent volume with the power of the explosive (Fig. 7.23, Tab. 7.7). 

Fig. 7.23 Small Scale Shock Reactivity Test (SSRT test) schematic drawing (top left), photograph of test set-up (top right) and dents in solid aluminum disks after the test.

Tab. 7.7 SSRT test results for three high explosives (RDX. CL-20 and TKX-50).

In the SSRT testing, creep stands for time-dependent deformation of the sample after the load application. Maximum load is defined as the load that results in the failure of one component. The strain rate is the initial rate of increase of the gage length of an initial... 

Fig. 9.8 Effect of strain rate ductility in SSRT testing for HIC and SCC [20]. Reprinted, with permission, from ASTM STP 665, Stress corrosion cracking - the slow strain rate technique, Copyright ASTM International, West Conshohocken, PA [20],...

In the case of HIC, hydrogen diffuses into the lattice at all strain rates tested and no ductility is observed on the reduction in the area vs. strain rate plot. At the critical strain rate, in the case of SCC, the film formation cannot inhibit the ductile mpture [20]. Threshold stresses can also be determined by SSRT tests. The test is performed by using a number of samples that are subjected to different ranges of stress at a given strain rate. A plot of stress range vs. average crack velocity could be used to evaluate the threshold stress [20]. 

NaCl at pH 1 was found to be sensitive to a variation in the solution temperature. A decrease of the solution pH and the increase of chloride concentration at 25 °C increased the polarization current while decreasing the passive region. The mechanical properties, such as the maximum tensile strength (MTS), fracture strain (FS), and reduction in area (RA), decreased at pH < 3 in 5 M NaCl at 25 °C. SCC was also found to be initiated in NaCl solutions at pH 1 in the presence of chloride concentrations higher than 1 M. The results of the SSRT test and the SCC susceptibihty of AUoy 690 in 1 M NaCl at pH 1 were found to depend on the solution temperature. Figure 9.43a shows the stress-strain... 

Results of the SSRT tests of type 321 stainless steel in a simulated petrochemical environment containing sulfides and chlorides indicated that the effects of environmental... 

The effect of plasma electrolytic oxidation (PEO) treatment on the SCC of surface-modified magnesium alloys was studied [167]. PEO coating offered improved corrosion resistance. However, the barrier film did not improve the SCC resistance in ASTM D 1384 test solution. The SCC of PEO-coated specimens was attributed to the development of micro cracks in the coating, leading to substrate cracking under SSRT test conditions [167]. 

Factors affecting the electrochemical behavior and See of Alloy 690 in a chloride environment were investigated by Chen et al. [164] using a cyclic polarization method and a SSRT test. 

Figure 4.17 Typical load vs. time curves generated by SSRT tests of mild steel in the environments consisting of a mixed SRB culture, abiotic non-sterile containing 3.5% sodium chloride solution alone, whereas the abiotic sterile environment contained modified Postgate B medium along with some chemicals to keep it sterile [106]...

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