Welding wire for gas shielded welding of aging martensitic stainless steel

Abstract

The present invention relates to a welding wire suitable for welding aging martensitic stainless steel. The welding wire comprises the following chemical components, by weight percent: 0.01-0.09% of C, 0.2-0.6% of Si, 0.2-1.0% of Mn, less than or equal to 0.025% of P, less than or equal to 0.025% of S, 14-17% of Cr, 4.2-5.8% of Ni, 3.0-4.0% of Cu, 0.1-0.5% of Nb, less than or equal to 0.75% of Mo and the balance of Fe. The welding wire used for welding 15-5PH aging martensitic stainless steel can avoid forming a ferrite net in the martensitic tissue of a welding seam, so that the plasticity and the toughness of a joint are ensured, and the welding wire also has superior welding properties and can effectively avoid welding thermal cracks. After being used for welding the 15-5PH stainless steel, the welding wire has favorable all-round properties by complete heat treatment and is suitable for the gas shielded welding of the aging martensitic stainless steel in the fields of the aviation industry and other industries.

Description

technical field [0001] The invention belongs to a welding wire used for gas shielded welding of 15-5PH and other aging martensitic stainless steels. Background technique [0002] 15-5PH and 17-4PH steels belong to martensitic precipitation hardening stainless steel. The Ms point of this kind of steel is higher, and the Mf point is above room temperature. Therefore, after solution treatment, almost all martensitic structures can be obtained. At the same time, because it contains strengthening elements such as Cu, Al, Mo, Ti, Nb, etc., which have a small solid solubility in martensite, it can achieve the effect of aging strengthening after low temperature tempering. 15-5PH and 17-4PH mainly rely on the copper-rich phase precipitated by aging to produce precipitation hardening effect. 15-5PH can be used to manufacture load-bearing parts that work under atmospheric conditions and parts that are in contact with fuel and work below 300°C, such as aircraft skins, frames, honing ba...

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Problems solved by technology

At present, welding 15-5PH is usually recommended to use 17-4PH material welding wire [American Welding Society edited. Welding Handbook, Volume Four, Seventh Edition, P188. Beijing: Machinery Industry Press, 1991], using this welding wire to weld 15-5PH Due to the presence of a certain amount of δ ferrite in the weld, it has high resistance to welding hot cracks, but the use of this welding wire has the disadvantages of reduced ductility and plasticity of the weld and mismatch of corrosion resistance between the weld and the base metal

A certain amount of δ ferrite with high Cr content will be formed in the weld martensite structure of 15-5PH steel welded with 17-4PH material welding wire, which will be further decomposed and separated into a very brittle Cr-rich phase during tempering , worsen the mechanical properties of the weld, especially the impact toughness of the weld; at the same time, due to the difference between the microstructure of the weld and the heat-affected zone and the base metal, the corrosion resistance is reduced, especially the stress corrosion resistance is significantly reduced

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