Performance of Almen Strips which are Straightened after Tempering

Author:  Champaigne
Source:  Conf Proc: ICSP-8 Sept. 16-20, 2002 Garmisch-Partenkirchen, Germany
Doc ID:  2002017
Year of Publication:  2002
Abstract:  
Author Jack M. Champaigne, Electronics Inc., Mishawaka, IN, USA Introduction Almen strips are test coupons used to determine the intensity of the shot blast stream during the shot peening process. Strips are manufactured in accordance with SAE J442 [1]. Standard manufacturing practices involves cutting strips from (soft) coil stock, heat treating and quenching to HRC 62 and then heat setting with clamping during tempering to provide strip flatness and low values of compressive stress on both sides of the strip. An alternative (hybrid) method of manufacturing was investigated. The method involved hardening and tempering (44-50 HRC) strip stock in a coil, straightening at room temperature and then cutting to length. One piece of each type of strips (standard and hybrid) was examined by X-ray diffraction to obtain residual stress distribution measurements. Readings were taken on both sides of these strips prior to peening and the results are shown in Figure 5. Differences in strip response to peening of 30 strips of each type were evaluated using two shot sizes and four Almen intensities. Tests at various peening intensities were conducted to compare the performances of standard strips and these hybrid strips.