Regarding stainless steel weld seam treatment methods, Senyuan provides a variety of solutions. CA-Q04 produced by Senyuan can process stainless steel weld seams very well and is suitable for weld seam treatment of 200, 300, and 400 series stainless steel, including austenitic. Stainless steel, ferritic stainless steel, martensitic stainless steel, and duplex stainless steel can all effectively and quickly remove welds.

Weld treatment method of ferritic stainless steel

(1) Ferritic stainless steel does not undergo phase transformation during heating and cooling, and does not undergo quenching hardening.

(2) The parts heated to above 950°C (welds and heat-affected zones) have a serious tendency to grow grains, and post-weld heat treatment cannot be used to refine coarse grains, which reduces joint toughness and increases the tendency of cold cracking.

(3) If the weld and heat-affected zone stay in the temperature range of 400~600℃, “475℃ brittleness” will easily occur. Staying in the temperature range of 650~850℃ will easily cause 8-phase precipitation and embrittlement.

(4) When welding, attention should be paid to the heating and cooling rates in the above two temperature ranges. Short-term heating above 600℃ followed by air cooling can eliminate 475℃ embrittlement; heating to 930~980℃ and rapid cooling can eliminate phase precipitation embrittlement.

(5) Preheating before welding can prevent cracks.

Weld treatment method of martensitic stainless steel

(1) Martensitic stainless steel has a strong hardening tendency, and a coarse martensite structure is easily produced in the heat-affected zone during welding. The higher the carbon content of the base metal, the greater the hardening tendency.

(2) The residual stress after welding is large and cold cracks are easily generated. Increased hydrogen content in welded joints will increase the tendency of cold cracking.

(3) Martensitic stainless steel will have a greater tendency to overheat. In the areas of welded joints that are heated above 1150°C, the grains will grow significantly. Too fast or too slow cooling may cause joint embrittlement. In addition, martensitic stainless steel, like ferritic stainless steel, is also brittle at 475°C. Preheating before welding and heat treatment after welding must be paid attention to.

Weld treatment method of duplex stainless steel

Duplex stainless steel has good weldability. Although its solidification and crystallization is single-phase ferrite, under general restraint conditions, the hot crack sensitivity of the weld metal is very small. When the proportion of the duplex structure is appropriate, its cold Crack susceptibility is also lower. However, it should be noted that duplex stainless steel has higher ferrite after all. When the degree of restraint is large and the hydrogen content of the weld metal is high, there is still a risk of welding hydrogen-induced cracking. Therefore, the source of hydrogen should be controlled during welding material selection and welding process.

Weld treatment method of precipitation hardened stainless steel

Precipitation hardening martensitic stainless steel has good weldability. When welding the same material with equal strength, if the degree of restraint is not large, preheating or postheating before welding is generally not required. The postweld heat treatment adopts the same low temperature as the base metal. Tempering aging will produce welded joints of equal strength. When welding joints of equal strength are not required, austenitic welding materials are usually used for welding. There is no preheating or postheating before welding. There will be no cracks in the welding joint. In the heat affected zone, although a martensite structure is formed , but due to the low carbon content, there is no strong hardening tendency, and welding cold cracks will not occur when the degree of restraint is not large. It is worth noting that if the segregation of strengthening elements in the base metal is serious, such as the quality of the casting is poor, the weldability and plastic toughness of the welding heat-affected zone will be deteriorated.

Precipitation hardened semi-austenitic stainless steel has good weldability. When the weld and the base metal have the same composition, that is, when welding of the same material is required, the following problems may occur under the action of the welding heat cycle.

1. Excessive ferrite content in the weld and near-seam areas may cause embrittlement of the joint. 2. The strength of the welded joint is difficult to match that of the base material.

When welding of the same material with equal strength is not required, commonly used austenitic welding materials can be used. There is no obvious crack sensitivity in the weld seam and heat-affected zone.

Although precipitation hardened austenitic stainless steel A-286 steel has more age-strengthening alloy elements, its weldability is compared with the weldability of semi-austenitic precipitation-strengthened stainless steel. When using the usual fusion welding process, the crack sensitivity is small. , no preheating or postheating is required before welding. After welding, post-weld heat treatment is performed according to the aging treatment process of the base metal to obtain welded joints close to the same strength. For 17-10P steel, although the S content is strictly controlled, because the mass fraction of P is as high as 0.30%, the enrichment of phosphide in the grain boundaries at high temperatures is inevitable, resulting in a large susceptibility to hot cracking in the near-seam area. The properties and brittleness make it difficult to use the fusion welding process. Some special welding processes, such as flash welding and friction welding processes, are more suitable for the welding of this steel.

Cherry
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Email: Cherry@jinyoumetal.com
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