PDF Publication Title:
Text from PDF Page: 225
AC 43.13-1B 9/8/98 (10) Incomplete weld penetration is a failure of the weld metal to penetrate com- pletely through a joint before solidifying. (11) Incomplete weld fusion occurs in welds where the temperature has not been high enough to melt the parent metal adjacent to the weld. (12) Weld undercutting is a decrease in the thickness of the parent material at the toe of the weld caused by welding at too high a temperature. (13) Cracks in the weld metal can be caused by the contraction of a thin section of the metal cooling faster than a heavier section or by incorrect heat or type of filler rod. They are one of the more common types of flaws found in welds. (14) Weld crater cracks are star shaped cracks that can occur at the end of a weld run. (15) Cracks in the weld heat-affected zone can occur because of stress induced in the material adjacent to the weld by its expansion and contraction from thermal changes. (16) A slag inclusion is a nonmetallic solid material that becomes trapped in the weld metal or between the weld metal and the base metal. (17) Scale is an oxide formed on metal by the chemical action of the surface metal with oxygen from the air. d. Secondary Processing or Finishing Flaws. This category includes those flaws as- sociated with the various finishing operations, after the part has been rough-formed by roll- ing, forging, casting or welding. Flaws may be introduced by heat treating, grinding, and similar processes. The following are brief de- scriptions of some secondary processing or finishing flaws. (1) Machining tears can occur when working a part with a dull cutting tool or by cutting to a depth that is too great for the mate- rial being worked. The metal does not break away clean, and the tool leaves a rough, torn surface which contains numerous short dis- continuities that can be classified as cracks. (2) Heat treating cracks are caused by stresses setup by unequal heating or cooling of portions of a part during heat treating opera- tions. Generally, they occur where a part has a sudden change of section that could cause an uneven cooling rate, or at fillets and notches that act as stress concentration points. (3) Grinding cracks are thermal type cracks similar to heat treating cracks and can occur when hardened surfaces are ground. The overheating created by the grinding can be caused by the wheel becoming glazed so that it rubs instead of cutting the surface; by using too little coolant; by making too heavy a cut; or by feeding the material too rapidly. Gener- ally, the cracks are at right angles to the direc- tion of grinding and in severe cases a complete network of cracks can appear. Grinding cracks are usually shallow and very sharp at their roots, which makes them potential sources of fatigue failure. (4) Etching cracks can occur when hardened surfaces containing internal residual stresses are etched in acid. (5) Plating cracks can occur when hard- ened surfaces are electroplated. Generally, they are found in areas where high residual stresses remain from some previous operation involving the part. Page 5-4 Par 5-5PDF Image | AFS-640
PDF Search Title:
AFS-640Original File Name Searched:
ac_43.13-1b_w-chg1.pdfDIY PDF Search: Google It | Yahoo | Bing
5,000 BF Shipping Container Lumber Dry Kiln For Quality Lumber The 5,000 BF container kiln consists of one 40 foot high-cube aluminum shipping container... More Info
Shipping Container Lumber Dry Kilns by Global Energy Global Energy designed and developed the container kiln back in 1991. The purpose is to give access to portable sawmill owners, furniture makers, and small business the value added profit of dry kiln lumber and quality hardwoods... More Info
Vacuum Kiln Conversion Kit for Lumber and Wood Dry Kilns Convert your existing conventional dry kiln into a fast drying vacuum kiln. Similar to vacuum bagging in the boat building and aircraft industry, we have come up with a proprietary process which allows you to build a very simple vacuum kiln at a fraction of the price, and without the intensive conventional metal chamber structure... More Info
Vacuum Pump Cart System for Bagging Clamping Wood Drying and more Vacuum Cart with 2HP Pump and Dual Pistons with multiple multiplex vacuum ports and liquid reservoir... More Info
Vacuum Bagging Basics Vacuum bagging is a method of clamping, which has traditionally been used in the composites industry, but can also be used for vacuum drying materials, including wood products... More Info
| CONTACT TEL: 608-238-6001 Email: greg@globalmicroturbine.com | RSS | AMP |