Problems of blackening of steel parts in technical practice

Sylvia Kuśmierczak,Martin Makovský,D Stančeková,N Čuboňová,A Sapietová,J Szabelski,M Vaško,J Mrázik,V Tlach,A Rudawska

doi:10.1051/matecconf/201824401012

Abstract

Problems of degradation are mainly solved in finished products, in a number of cases it is manifested during production. A great influence on the degradation processes of the products has the surface quality and surface finish. The article deals with the problem of blackening of steel, which has been treated with alkaline blackening. The throttle shaft made of automatic steel will be analyzed. Degradation was manifested by a change in surface quality after alkaline blackening. The methods of light and electron microscopy in combination with complex analysis of production flow and technology conditions were used for analysis. Based on the results of analyzes it was found that the degradation processes are closely related to the quality of preparation of the surface. Owing to the incorrect pretreatment of the surface, oxides occurred locally. At the sites of oxides, after alkaline blackening, the surface layer was peeled off, resulting in deterioration in the quality of the product.

Highlights

Degradation is primarily known as a manifestation of environmental influences or degradation of material properties for already finished products
Significant influence on degradation processes has the effect of surface quality and surface treatment
The aim of the paper was to show the problem of blackening of steel parts in technical practice, which has to solve the occurrence of defects on the components, which have been treated with alkaline blackening

Summary

Introduction

Degradation is primarily known as a manifestation of environmental influences or degradation of material properties for already finished products. The purpose of the surface treatments is to obtain a higher corrosion resistance of the product, to achieve the desired appearance or to improve the mechanical properties of the surface. It is mainly used as a finishing operation [6-8]. The principle of alkaline oxidation blackening consists in iron oxidation by immersion of ferrous metal products into a concentrated hot aqueous solution of a mixture of sodium hydroxide with a suitable oxidant and other ingredients added to the bath. The component being analyzed will be a throttle shaft that affects the amount of intake air into the engine

Description of the problem

Analysis of causes of part degradation

Conclusions