Technological, Microstructural and Strength Aspects of Welding and Post-Weld Heat Treatment of Martensitic, Wear-Resistant Hardox 600 Steel.

Łukasz Konat

doi:10.3390/ma14164541

Abstract

The study presents technological and structural aspects of production and heat treatment of welded joints of high-strength, abrasion-resistant Hardox 600 steel. As a result of the conducted research, it was found that the use of welding processes for joining this steel leads to the formation of a wide heat-affected zone, characterized by various structures favoring the reduction of abrasion resistance and deterioration of plastic properties, while increasing the susceptibility to brittle fracture. On the basis of the structural and strength characteristics, an effective welding technology for Hardox 600 steel was proposed, as well as the conditions and parameters of post-welding heat treatment, leading to obtaining structures close to a base material in the entire area of the welded joint. Despite the limited high-carbon equivalent CEV of the metallurgical weldability of the tested steel, the tests carried out in laboratory conditions allowed researchers to obtain welded joints characterized by very high strength indexes, corresponding to the base material, while maintaining satisfactory plastic and impact properties.

Highlights

Hardox 600 steel belongs to the group of alloys defined by their producer, i.e., the Swedish steelworks SSAB, as weldable, martensitic steel resistant to abrasive wear with boron [1]
The selection of the optimal austenitizing temperature was made taking into account an actual chemical composition of the base material (Tables 2 and 3) and based on the weld metal composition obtained as a result of welding within the entire cross-section of the weld (Figure 3 and Table 5)
Due to the fact that, along with the entire heat-affected zone of the welded joint Hardox 600, the zone of the base material is subject to volumetric heat treatment, it seems reasonable to determine the impact of these treatments on the selected mechanical indicators of the welded sheet

Summary

Introduction

Hardox 600 steel belongs to the group of alloys defined by their producer, i.e., the Swedish steelworks SSAB, as weldable, martensitic steel resistant to abrasive wear with boron [1]. It is worth noting that Hardox 600 steel, apart from Hardox Extreme, stands out significantly from other steels offered by the Swedish steel company, as well as by other steel producers with properties similar to Hardox steel It is characterized by an average hardness—. There are reasonable premises proving the possibility of using the high strength indexes of Hardox 600 steel for selected devices and machine parts, structural elements of which are joined by welding technologies. Very often, in this type of application, in addition to high tensile strength, engineering plastics must have an appropriate level of resistance to impact loads.

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Conclusion