ISSN:
1045-4861
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
,
Technology
Notes:
Four stainless steel alloys, commonly used for surgical needles were tensile and bend tested. The materials included: ASTM 42000, ASTM 45500, ASTM 30200, and a Fe-12Cr-8.5Ni-3.2Mo-1.9Ti alloy. Small diameter wires in a wide range of strength levels were produced using various heat treatments and/or cold drawing. Samples from each processing condition were tensile and bend tested. Calculated yield moment and ultimate moment were determined using tensile yield strength, the flexural formula (M(y) = σ(y) I/C), and the shape factor for circular cross sections (M(u)/M(y) = 1.7). A deviation was observed between the theoretically calculated yield moment and a 2° offset measured yield moment. This was expected because moment-strain diagrams provide only an approximation of yield moment due to the gradual departure from linearity. The 2° offset yield was termed the surgical yield because it represents the strain at which a surgical needle would start to lose functionality. A nonlinear relationship (R) was observed between measured and calculated values. The relationship (R) proved to be a function of cold work by wire drawing as measured by the change in wire length (ΔL), R = a - b * In(ΔL). This suggests that engineers selecting materials for bending applications such as surgical needles cannot use tensile data alone to predict bend strength. Processing history must also be known. © 1993 John Wiley & Sons, Inc.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jab.770040208
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