This paper describes the development of two iron-based alloys tailored for hardfacing applications typically fulfilled by Ni-WC overlay welding or laser cladding. The approach makes use of thermodynamic calculations and experimental testing to predict microstructure evolution during processing for different alloy compositions and how it is likely to influence final properties, specifically hardness and wear resistance.

This study shows how data-driven modeling tools aid in the development of alloys that meet specific processing, property, and performance requirements. By leveraging a “big data” approach, two new alloys were designed that outperform commonly used materials in hardfacing and wear plate overlay applications. Over one million alloy compositions were analyzed to find two with the right combination of matrix and hard phases to provide the desired level of impact and abrasion resistance. The difference between the two alloys is in their matrix phase; one being austenitic, which has higher toughness, the other being martensitic, which has higher resistance to abrasive wear.

Tungsten carbide in nickel based self-fluxing alloy overlays has been dominating hardfacing applications due to its excellent properties, namely extremely high wear resistance. Nevertheless, there are still applications and limits which tungsten carbide has not conquered. This study focuses on (TiW)C 1-x which was deposited with several matrix materials and tested in wear, corrosion and impact resistance and benchmarked against tungsten carbide. Results for several other carbides such as (NbW)C 1-x , (VW)C 1-x , NbC 1-x and TiC 1-x overlays deposited by plasma transferred arc (PTA) and laser cladding (LC) will be presented and discussed. As a result of deposition trials and overlay testing, it was found that better thermodynamic stability of alloyed carbides allows them to be used in an iron based matrix and/or a matrix with a high chromium content, in applications requiring improved corrosion and oxidation resistance, better impact resistance and lower weight.

New flame spray hardfacing, DSH (DuraShell Steel Hardfacing, US patent pending), is developed to improve thermal conductivity, abrasion wear and erosion resistance for subterranean drilling application. The hardfacing materials consist of spherical cast WC/W2C and Ni-Si-B alloy powders. The hardfacing compositions are tailored for flame spray and laser cladding processes. Typically, the hardfacing comprises hard spherical cast WC/W2C particles uniformly distributed in a tough Ni-alloy matrix. The hardness of WC/W 2 C exceeds 2100 Hv .3 and Ni alloy matrix varies from about 400 to 700 Hv .3 . High stress and low stress abrasion resistances of these hardfacings were characterized and compared to the conventional cast WC/W 2 C and Ni-Cr-Si-B-Fe hard coating. The increase in thermal, wear, and erosion resistances of DSH hardfacing improve the durability of PDC steel body bits and drilling tools and their cost effective performance. Several case studies of DSH hardfacings on drill bits are described.

This paper discusses the development of Fe-Cr-C-B powder feedstocks for the production of wear-resistant coatings by HVOF spraying. Chromium content in the powder is in the range of 30 wt% and carbon content is about 5 wt%, yielding a unique powder structure that results in coatings with high and well distributed carbide content. Powder and coating microstructure are examined and the results of wear tests are presented. The extent to which the powders can substitute for conventional carbide coatings is discussed as well.

Current thermal spray chrome replacement and hardfacing materials primarily use WC or Cr 3 C 2 as hardphase materials and contain chrome. A series of cermet alternatives based on lower weight and cost ceramic particles including alumina, silicon carbide, boron carbide and titanium nitride were applied via HVOF and tested for wear and frictional properties under various loading conditions. Furthermore, based upon highly promising initial results, thermal spray particle designs were modified for lower cost and improved performance.

Typically, highly wear resistant PTA materials for mining and mineral processing applications are developed by adding ceramics like tungsten carbide to appropriate matrices. The problem is that failure during abrasion can often occur as a result of preferential wearing of the soft matrix material or crack formation through the highly loaded brittle ceramic phases. In this paper, the development of new highly wear resistant plasma transferred arc (PTAW) iron based alloys will be detailed. In this case, the matrix material itself was found to have excellent abrasion resistance with high hardness obtained in the weld deposits up to Rc 66 from the development of a fine structure consisting of a high volume fraction of complex M23(BC)6 and M7(CB)3 borocarbides phases. The matrix material is found to additionally exhibit high toughness up to 73.3 MPam1/2 due to an effective distribution of fine carbide and boride phases in a ductile dendrites / cells. When adding WC particles to the starting powder and welding, the matrix was found to effectively wet the WC particles forming a strong tough matrix which avoids the typical “pull-out” or cracking found in conventional PTAW hardfacing materials. Specific weight loss measurements were conducted using ASTM G-65 wear testing and will be correlated to the structure achieved during PTAW. Abstract only; no full-text paper available.

The unique wear protection properties of tungsten carbide metal matrix composite materials are resulting in their increasing use in the oilsand industry to combat severe low stress sliding abrasion and various types of slurry abrasion and erosion. Their successful application, mainly in bulk welding and spray coating forms, has extended component service lives, improved reliability and reduced maintenance costs. Increased use of tungsten carbide metal matrix composite hardfacing deposits in oil sands applications is the direct result of understanding carbide thermal degradation and the processes used to deposit these materials. Plasma transferred arc welding (PTAW) has proven to be an effective process for applying these materials. Current and future work on PTAW and other candidate processes to establish the optimum carbide hardfacing method will be reviewed.

This paper presents the bases of a methodology for purchase, installation and use of equipment for thermal spraying, hardfacing and sand blasting. This methodology takes all currently known personnel and environmental regulations into account. Businesses already using the above-mentioned techniques as well as future users will find it useful as it gives details about how to meet the current obligations and to correctly evaluate the resources needed to design not only efficient, but also safe and environment-friendly workshops. To be more user-friendly, the necessary information for setting up a complete installation can be structured and presented under the form of notices which could constitute the basis of a user’s guide.

This paper discusses some of the recent improvements in plasma powder surface build-up welding technology and provides examples of its use in different areas of industry. It describes the coating properties achievable with newly developed filler alloys and how they compare with conventional hardcoats. It also discusses the growing use of manual overlay PTA welding among small and midsize companies and the factors behind it. Paper text in German.

Hard surfacing layers of WC-Co/Ni-based self-fusing alloy (SFA), Ni-based SFA and Cr 3 C 2 -NiCr alloy were formed using powder and an electron beam. When the layers were examined using the Vickers hardness test, a sand erosion test and an immersion corrosion test, they were found to display high erosion and corrosion resistance. The WC-Co/Ni-based SFA, Ni-based SFA, and Cr 3 C 2 -NiCr alloy layers displayed high hardness of 1400HV, 780HV and 900HV, respectively.