The Effect of Different Modifiers in AlSi7Mg0.3 Alloy on Built-up Edge Formation in Machining

The usage of aluminium alloys has an increasing trend in the manufacturing industry in recent years. This fact is connected with their ability to combine their very good properties. Characteristics of aluminium are low specific weight, very good thermal and electrical conductivity, and ductility. However, the major disadvantages are low strength and hardness. Therefore the aluminium alloys are alloyed with the elements, which would significantly improve the properties of aluminium. The machining process of aluminium alloys is influenced by many factors that affect the machinability. These factors are for example process conditions, cutting tool material, cutting tool geometry, cutting environment or the chemical composition of the machined material itself and microstructure of the workpiece. Due to the different structures, the machinability of aluminium alloys and pure aluminium is significantly different. Factors such as chemical composition, precipitates, the number and position of soft particles or the strain hardening degree affect the behaviour between the cutting tool and the workpiece during machining. When machining the aluminium alloys, there are some problems such as the surface quality, micro-geometry, tool wear, the chip shape, built-up edge formation, etc. The article deals with the surface defect investigation after the machining process, when on the surface of the material stay the visible "snowflakes" after the turning operation. These "snowflakes" were documented and were performed analysis and observation to find the cause of these flakes.

Identification of the "Snowflakes" on the Machined Surface of the AlSi10Mg Alloy Casting

Svobodová¹,

Luňák²,

Lukáč³

2019

Built-up Edge Formation in Machining AlSi7Mg0.3 Alloy

Martinovsky¹,

Mádl²,

Vitner³

2016

One of the main problems in machining Al alloys represents built-up edge formation. This paper is focused on the effect of selected modifiers in AlSi7Mg0.3 alloy on built-up edge formation. Four variants of castings modified by strontium, calcium and antimony are used. All these alloys are compared with non-modified alloy. Built-up formation leads to the increasing of surface roughness for both types of built-up edge -unstable or stable. If unstable built-up edge is produced, surface roughness increases enormously. Therefore the research is focused on surface roughness in different cutting conditions. There were moulded castings of non-modified alloy and for each modified variant. Gravity-die castings into a metal mould with a thermal insulation were made.

Influence of the Bending Momentum Loading of Testing Samples from the Alloy AlSi7Mg0.3 on the Surface Stress State Detected by X-ray Diffraction

Řidký¹,

Sobotka²

2016

These days are more and more posing claims for the highest quality of castings from the aluminium alloys and for the lowest weight of these castings. Thus for complex material (in this case alloy) utilization it is very important to monitor its behavior both during production (chemical composition, metallographic evaluation of the structure, observance of thermal treatments temperatures, refining and degassing of melt and so on) and also during its loading. This papers deals with the monitoring changes of stress on the testing samples surface arising from the force loading. As a loading there was a bending momentum at the testing samples (rods) from the alloy AlSi7Mg0,3 which was poured into the metal mould after the different thermal treatment methods. Bending momentum increased up to the expressive deformation of the tested sample. Results were also completed by the depth profile of the residual stresses which were measured by means of the X-ray diffraction (X-ray tensiometry analysis) namely for all thermal treatment methods. Moreover in the depth profile there was also performed the qualitative evaluation of the structure by the back-reflection Debye-Scherrer method.