ASTM D1693:01 pdf free download – Standard Test Method for Environmental Stress-Cracking of Ethylene Plastics.
10.2 Give each conditioned specimen a controlled imperfection (notch) on one surface as shown in (A) of Fig. 2. Use a sharp blade, mounted in the jig shown in Fig. I. for making this imperfection. A depth micrometer may he used fhr setting the blade in the jig so that the notch depth is controlled as specified in Table 1. The difference between the height at the top of the blade edge and the channel of the jig where the top of the specimen rests when being nicked is measured to ensure the proper setting of the blade.
NOTE 11—Where it is desired to nick specimens to a notch depth required by Conditions B and C in Table 1 and the available jig has been designed for nicking specimens to a notch depth required by Condition A in Table 1, brass shim stock 0.21 mm (0.(X)8 in.) thick may be used to make the more shallow notch. Brass shim stock is cut wide enough so that it fits snugly inside the jig channel where the specimen rests when nicked. The length of the shim should he such that it extends over the blade, around the end of the jig. and under the end so that the jig will rest on about I or 2 in. of the shim stock, The weight of the jig resting on the shim stock prevents deformation of the shim stock during the nicking operation. An oblong hole long enough to ti completely over the protruding blade is cut in the other end of the shim stock. Discard shim stock that becomes wrinkled or deIrmed in such a way as to prevent the specimen from lying horizontal in the jig.
NOTE 12—In order to maintain notch consistency, it is recommended to keep the force applied to the jig handle Constant. This can be done by applying the force at the same l(xaIion of the jig handle each time using a torque wrench.
NOTE 13—The notch depth correlates with the depth of blade Setting. which is measured by a depth micrometer (see 10.2). The notch depth can he verified by microloming the cross section of the specimen followed by examining the slice under microscope. It also can be done by fracturing a notched specimen after it is cxled with liquid nitrogen then examine the fracture surface under microscope.
Nom 14—Check notch quality for straight edge, sharp notch and free of stress concentration area by examining the cross section of the specimen under microscope equipped with a polariied light.
10.3 Inspect the edge of the blade for notches and burrs under normal vision prior to the first nicking and at least alter each 30 successive nicks have bccn performed. in no case shall a blade be used for more than 100 specimens. Replace the blade whenever there is any question of its having become dull or damaged.
10.4 Place ten specimens, with the controlled imperfection up, in the slots provided in the bending clamp. Close the clamp by means of a vise, arbor press, or other suitable aid, taking 30 to 35 s for the complete closing operation. Place the transfer tool in position on top of the closed clamp and close it over the specimens.