Selecting the Best Stainless Steel Welding Rods

The Selection Criteria for Welding Rods

1.Reference the material and model of the base metal and choose a welding rod with a similar or identical composition to the base metal. Pay special attention to the carbon content; for stainless steel, use a welding rod with a carbon content not higher than that of the base metal.

2. For corrosion-resistant stainless steel operating in various corrosive environments, select welding rods based on the medium and operating temperature. When the operating temperature exceeds 300°C and the medium is highly corrosive, choose stainless steel welding rods containing stabilizing elements such as Nb or Ti, or ultra-low carbon.

For working with dilute sulfuric acid or hydrochloric acid, stainless steel welding rods containing Mo or Mo and Cu are commonly chosen. For products operating at room temperature with a less corrosive medium, stainless steel welding rods without Nb or Ti can be used.

3. For heat-resistant stainless steel operating at high temperatures, the selected welding rods should primarily meet the high-temperature performance requirements of the joint and enhance the resistance to hot cracking of the weld metal. When welding austenitic heat-resistant steel with Cr/Ni≥1, stainless steel welding rods containing 2% to 5% ferrite are generally used.

When welding stable austenitic heat-resistant steel with Cr/Ni<1, ensure that the weld metal composition is approximately similar to the base metal while increasing the content of elements such as Mo, W, and Mn in the weld metal to provide high thermal strength and crack resistance.

4. For chromium stainless steel, to achieve the inherent corrosion resistance (oxidizing acids, organic acids, erosion), heat resistance, and wear resistance, select chromium stainless steel welding rods with a composition similar to the base metal. Additionally, employ appropriate preheating and post-weld heat treatment measures.

Sometimes, to improve the weld joint’s plasticity and simplify the welding process, chromium-nickel stainless steel welding rods (such as A107, A207, etc.) can be used without post-weld heat treatment.

5. Regarding the selection of flux types, stainless steel welding rods differ from structural steel welding rods. Superior ductility and resistance to cold cracking are no longer the main concerns in stainless steel welding. Thus, alkaline stainless steel welding rods are only used when welding martensitic stainless steel or large structures.

In recent years, the excellent welding process performance of titania-type flux (-17 type) has been widely adopted both domestically and internationally. The titania-calcium flux (-16 type) also exhibits excellent welding process performance and is more suitable for all-position welding, remaining one of the commonly used flux types.

Welding Rod Usage Precautions

Redrying of Welding Rods

Moisture-absorbing welding rods should undergo redrying, especially titania-type rods, which are highly sensitive to porosity and require strict redrying. Titania-calcium rods can be redried at 150°C for 1 hour, while titania-type rods should be redried at 250-350°C for 1 hour.

Welding Current

To prevent the flux coating from reddening and cracking, and to reduce the tendency for intergranular corrosion due to heating, the welding current for stainless steel should not be excessively high, typically reduced by about 20% compared to carbon steel rods.

Welding Operation Key Points

Use short arc welding as much as possible and avoid lateral swinging. When striking the arc, use an arc plate, and when extinguishing the arc, ensure the crater is filled to prevent crater cracking.

Preheating

To avoid cold cracking, preheat martensitic stainless steel to 200-400°C. The preheating temperature for ferritic stainless steel should not be too high, ideally 100-200°C. Preheating is not necessary for austenitic stainless steel, and the interpass temperature should be kept relatively low, generally below 250°C.

Post-Weld Heat Treatment

For martensitic stainless steel, post-weld heat treatment can restore the plasticity and toughness of the weld and the heat-affected zone. For ferritic stainless steel, it can also restore its plasticity, with little change in toughness. Strict adherence to specifications is necessary.

Welding rods compatible with stainless steel grades

The Welding Rods Compatible with Stainless Steel Grades are listed in Table 2-69.

Table 2-69: Stainless Steel Grades and Their Compatible Welding Rod Brands

categorygradewelding rod brand
austenitic stainless steel00Cr18Ni10   0Cr18Ni9TiA002    A002Mo 
00Cr17Ni15Si4NbA012Si 
00Cr18Ni12Mo2   00Cr17Ni14Mo2  00Cr17Ni14Mo3A022       A212
00Cr18Ni12Mo2CuA032
00Cr22Ni13Mo2A042
0Cr18Ni9    1Cr18Ni9A102     A102A      A107
0Cr18Ni9Ti      1Cr18Ni9TiA132     A132A      A137
0Cr18Ni12Mo2(Ti)          1Cr18Ni12Mo2(Ti)A201     A202        A207     A212
0Cr18Ni12Mo3Ti         1Cr18Ni12Mo3TiA242
1Cr25Ni13        0Cr23Ni13      1Cr25Ni18           0Cr25Ni20   3Cr18Mn11Si2N      2Cr20Mn9Ni2Si2NA302     A302A     A307     A402       A407
4Cr25Ni20(HK-40)A432
Cr16Ni25Mo6      Cr15Ni25WTi2B A502     A507
Cr20Ni32        Cr18Ni37A607
0Cr17Mn13Mo2N(A4)A707
0Cr18Ni18MoCu2TiA802
martensitic stainless steel1Cr13      2Cr13G202   G207   G217   A302   A307   A402   A407
1Cr17Ni2G302   G307    A102    A107    A302    A307    A402    A407
Cr11MoV R802  R807
Cr12WMoVR817
ferritic stainless steel0Cr13G202   G207   G217   A102A    102A   A102   A107   A302   A307   A402   A407
0Cr17    0Cr17Ti   1Cr17Ti G302   G307   A102   A102A    A107   A302   A307
Cr25Ti A302   A307
Cr28     Cr28TiA402   A407    A412

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