Production process parameters optimization and characterization of aluminium stainless steel bimetallic castings

Abstract

Ability to join the ferrous and non-ferrous materials initiate a new newlineera of materials age to produce functionally graded lightweight components newlinewith enhanced/ combination of properties for heat transfer, defence, aerospace, newlineand automotive applications. Bimetals are the dissimilar metal/alloy newlinecombinations casted in a single or two stages to produce a metallurgically newlinebonded monolithic part with two/more distinct properties. Bond quality of newlinebimetallic castings depends on the process parameters employed during casting newlineand solidification process. In this research, Aluminium- stainless steel newlinebimetallic pipe castings were produced by lost foam compound casting method, newlinewhere decomposable thermocol moulds were used. Molten pure aluminium newlinewas poured over SS 304 stainless steel pipe (18 mm ID X 30 mm height) to get newlinea bimetallic pipe (50 mm OD X 30 mm height) for hot chemical transfer newlineapplications. The produced castings were machined and polished for further newlinecharacterization and testing using Optical Microscopy, Scanning Electron newlineMicroscopy with Energy Dispersive Spectroscopy, liquid penetrant testing and newlineshear punch test. The influence of important process parameters like Pouring newlineTemperature (PT), Insert Temperature (IT), Insert Thickness (ITC), surface newlineroughness (Ra) and interlayer/bond coatings over the pipe were correlated with the newlineresultant bond strength of the produced castings. Hybrid optimization techniques newlineconsists of Response Surface Methodology (RSM) and Genetic Algorithm (GA) newlinewere used to optimize these process parameters to get the maximum bond strength newlinein the produced BmCs. newlineInitially, twenty seven experiments were planned as per the newlineBox-Behnken design of experiments method accounting the pouring newlinetemperature (670and#61551;C to 730and#61551;C), insert preheat temperature (100and#61551;C to 400and#61551;C), newlineinsert thickness (1 mm to 3 mm), and surface roughness (0.3 µm to 0.9 µm) newlinewith the above mentioned maximum and minimum values as inputs. newline