Obtaining the mechanical properties of a head, connecting rod and piston of a 100cc two-stroke mono-cylinder engine, applying reverse engineering

Abstract

Obtaining the mechanical properties from reverse engineering or technological disaggregation of automotive parts and pieces allows us to know first-hand the chemical composition, structure, hardness, geometry, among others, that facilitate the design and manufacturing process in this particular case of a prototype connecting rod, piston and stub head, which are part of a 100cc two-stroke engine. For this purpose, both national and international standards have been considered to standardize the processes and that the results are comparable with related research, these standards being: ASTM E10-01 (Standard Test Method for Brinell Hardness of Metallic Materials), ASTM E18-03 ( Standard Test Methods for Rockwell Hardness and Rockwell Superficial Hardness of Metallic Materials), ASTM E3 - 01 (Standard Practice for Preparation of Metallographic Specimens), ASTM E407 - 07 (2015) e1 (Standard Practice for Microetching Metals and Alloys), ASTM E1251 - 17a (Standard Test Methods for Analysis of Aluminum and Aluminum Alloys by Spark Atomic Emission Spectrometry), ASTM E350 - 18 (Standard Test Methods for Chemical Analysis of Carbon Steel, Low-Alloy Steel, Silicon Electrical Steel, Ingot Iron, and Wrought Iron) . For the particular case of the motor head, the following results are obtained: composition: 19.53% Silicon, 1, 798% Copper and 76.12% Aluminum (hypoeutectic composition), and quickly tempered in water, which corresponds to an Aluminum 392 series, with a hardness of 108 HB. The following results were obtained for the engine connecting rod: Microstructure composed mainly of martenite and austenite, the average connecting rod hardness is 61HRC, with the following chemical composition: 0.252% carbon, 1.103% Manganese, 1.179% Chromium, 0.296% Silicon, responding to Cr-MN steel, with a tempering and tempering heat treatment. The following results are obtained for the piston: piston hardness 30.3 HB, chemical composition: 29.49% Silicon, 5.657% Copper, 1.898% iron, responding to a hypoeutectic aluminum Si-Cu, and responding to a 300 series, with heat treatment of tempering and artificial aging.