Extrinsic Influence of Environment on Tensile Response, Impact Toughness and Fracture Behavior of Four Metals: Ferrous Versus Non Ferrous

In this thesis report an attempt is made to present and briefly discuss the specific influence of exposure, by way of immersion, to four different environments, pH+Salt, salt, pH and distilled water, for four chosen time period of one-week, two-weeks, threeweeks, and eight-weeks on the static (uni-axial tensile) and dynamic (impact) properties of two ferrous metals [i.e, 304L stainless steel, and alloy steel 4340 CF] and two nonferrous metals [i.e., aluminum alloy 6061-T651 and aluminum alloy 7075].Test specimens for both tensile tests and Charpy V-Notch impact tests on the as-provided material were precision machined and conformed to standards specified by the American Society for Testing Materials (ASTM).The pH and conductivity were measured using a pH meter and a conductivity meter.The pH and conductivity were measured in an attempt to establish the acidity-level or alkalinity-level of the chosen mediums.The impact toughness response and resultant fracture behavior of the four chosen metals, subsequent to their exposure, by way of immersion, for chosen time periods were studied over the temperatures range -180C to +170C.The tensile tests were performed in the room temperature (25 o C), laboratory air (RH 55 pct.) environment.Final fracture behavior of the chosen metals was determined at both the macroscopic and fine microscopic levels.This was made possible following careful examination in a scanning electron microscope.After analyzing the data obtained it was observed that Salt medium was more corrosive among all the four environments and Distilled water was corrosion resistant medium.Steel was more corrosion resistant compared to Aluminum. 5.1.A schematic showing dimensions of the Charpy V-Notch test specimen.265.2 A schematic showing dimensions of the cylindrical test specimen used for Mechanical testing (Tensile)..27 7.1 Variation of pH and conductivity for tensile samples of aluminum alloy 6061, which were immersed in the pH+Salt medium for eight weeks34 7.2 Variation of pH and conductivity for tensile samples of aluminum alloy 6061 that were immersed in the salt medium for eight weeks...34 7.3 Variation of pH and conductivity for tensile samples of aluminum alloy 6061 that were immersed in the pH medium for eight weeks35 7.4 Variation of pH and conductivity for tensile samples of aluminum alloy 6061 that were immersed in distilled water for eight weeks..35 7.5 Variation of pH and conductivity for tensile samples of 304L stainless steel that were immersed in the pH+Salt medium for eight weeks..37 7.6 Variation of pH and conductivity for tensile samples of 304L stainless steel that were immersed in a salt-containing medium for eight weeks....37 7.7 Variation of pH and conductivity for tensile samples of 304L stainless steel that were immersed in a pH medium for eight weeks...38 7.8 Variation of pH and conductivity for tensile samples of 304L stainless steel that were immersed in distilled water for eight weeks.....38 7.9 Variation of pH and conductivity of the impact test samples of aluminum alloy 7075 that were immersed in an Acid + Salt medium for eight weeks...40 7.10 Variation of pH and conductivity for the impact test samples of aluminum alloy 7075 that were immersed in a salt medium for six week.....40 7.11 Variation of pH and conductivity for the impact test samples of alloy steel 4340 CF that were immersed in an acid + salt medium for eight weeks.......41 x 7.12 Variation of pH and conductivity for the impact test samples of alloy steel 4340 CF that were immersed in a salt medium for six weeks...41 7.13 Influence of temperature on impact toughness of aluminum alloy 7075 T651 that was exposed to two environments: Acid + salt and Salt for a time span of 4 weeks and 8 weeks..44 7.14 Influence of temperature on impact toughness response of alloy steel 4340 CF when exposed to the environments of Acid + salt and Salt for a time span of 4 weeks and 8 weeks.45 CHAPTER I