Treatment of AM 355 Steel for Adhesive Bonding.
Abstract
Surface treatments for AM355 prior to adhesive bonding have been developed. A sulfuric acid-dichromate immersion treatment and nitric acid anodization treatment have produced extremely strong durable bonds. Wedge test values (at 50 degrees C using 0.040 in. (0.102 cm) stock) are about 0.05-0.06 in./24 hr (0.13-0.15 cm/24 hr). Using a method now in use (HP4-121) results of greater than 1 in/day (2.5 cm) are obtained. Stress durability (ASTM D2919, 60 degrees C, 100% RH, 2000 psi (13.8 mPa)) tests show an average time to failure of about 500 hrs compared to the less than 1 hour time to failure obtained using the present method. It was found that increased bond durability, measured by the wedge test, was directly related to the increased chromium content of the surface oxide layer produced using these and other treatments. Experiments indicate that AM355 is essentially impermeable to hydrogen, i.e., the diffusion coefficient was unmeasurable using an electrochemical technique sensitivite to 0.1 ppm of mobile hydrogen. Although both methods mentioned above are commercially applicable, the HNO3 anodize appears the best because of the absence of carcinogenic dichromates, the lower production cost and slightly better bond results. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1979
- Accession Number
- ADA074113
Entities
People
- Ron Haak
- Tennyson Smith