Chromium-Free Hardfacing Welding Consumable for Hexavalent Chromium Reduction
Solution Overview
Problem
Chromium-based welding wires used in hardfacing applications emit Hexavalent Chromium, posing health risks to end users due to its harmful effects, necessitating the development of Chromium-free alternatives that maintain wear resistance and hardness.
Innovation Solution
A Chromium-free hardfacing welding consumable composition comprising specific percentages of elements like Carbon, Manganese, Silicon, Boron, Nickel, Titanium, Niobium, Tungsten, and Molybdenum, which form a martensitic weld deposit matrix with finely dispersed carbides and borides, reducing Hexavalent Chromium emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If Chromium is added to welding wire to improve wear resistance and hardness, then the wear resistance and hardness of the weld deposit are improved, but Hexavalent Chromium emissions occur which pose health risks to end users
Solution Approach 1:
The patent removes Chromium entirely from the welding wire composition to eliminate Hexavalent Chromium emissions. The Chromium-free formulation extracts the harmful element while maintaining wear resistance and hardness through alternative alloying elements such as Molybdenum, Tungsten, Nickel, and Titanium, which provide equivalent protective properties without the health hazards associated with Chromium emissions
Solution Approach 2:
The patent combines multiple alternative alloying elements (Molybdenum, Tungsten, Nickel, Titanium, Manganese, Silicon, and Boron) to collectively achieve the wear resistance and hardness previously provided by Chromium. This merging of multiple elements compensates for the removal of Chromium while eliminating harmful emissions
2Object-affected harmful factors
If Chromium-free composition is used to eliminate Hexavalent Chromium emissions, then health safety is improved, but wear resistance and hardness may be compromised
Solution Approach 1:
The patent changes the compositional parameters by eliminating Chromium and adjusting the percentages of alternative elements. Specifically, it incorporates 0.05-2.0% Molybdenum, 0.05-2.0% Tungsten, 2.0-10.0% Nickel, 0.5-5.0% Titanium, 0.5-3.0% Manganese, 0.1-1.0% Silicon, and 0.05-1.0% Boron to achieve the desired mechanical properties without Chromium, thereby maintaining wear resistance and hardness while eliminating harmful emissions
Solution Approach 2:
The patent creates a composite alloy composition without Chromium that combines multiple elements with complementary properties. Molybdenum and Tungsten provide high-temperature strength and wear resistance, Nickel enhances toughness and corrosion resistance, Titanium contributes to strength and wear properties, while Manganese, Silicon, and Boron provide additional hardening and protective effects. This composite formulation achieves equivalent or superior performance to Chromium-containing alloys without the health hazards
Data Source
AI summary
Compositions for Chromium-free hardfacing welding consumables are provided that include between approximately 0.3% and approximately 1.5% Carbon, between approximately 0.2% and approximately 2.5% Manganese, between approximately 0.3% and approximately 1.3% Silicon, between approximately 1.3% and approximately 5.5% Boron, between approximately 1.0% and approximately 4.0% Nickel, between approximately 1.0% and approximately 6.0% of at least one of Titanium and Niobium, and between approximately 0.1% and approximately 2.0% Tungsten and/or Molybdenum. Additional welding consumable compositions and weld deposit compositions are also provided to provide hardfacing materials with little or no Chromium content.