Why does a joint between two different steels get the lower steel's consumable?

CCS 5.1.4.2 says that when the steels differ in strength the consumable generally suits the lower strength steel, and that where the strength is the same but the toughness differs it generally suits the lower toughness steel. At structural discontinuities, in high stress areas, with complex loading or in harsh conditions a higher level may be chosen, which the tool shows when you tick the box.

When is a low hydrogen consumable needed?

CCS 5.1.4.3 asks for low hydrogen consumables generally when higher strength steel, or steel with a carbon equivalent above 0.41 %, is welded to steel of the same or lower strength, and for important structural members. Any joint with a higher strength steel falls in the first case.

Does the tool give preheat temperatures?

No. The rule lists when preheat and slow cooling should be considered and gives no temperatures. Above 0.45 % carbon equivalent it also asks you to consider post-weld heat treatment. The temperatures come from your approved welding procedure.

Engineering tool

Welding consumable selection

Choose the two hull steels in a joint. The tool lists the consumable grades that suit them from CCS Rules Table 5.1.4.1, applies the rules for joining steels of different strength or toughness, and flags when low hydrogen consumables, preheat or post-weld heat treatment should be considered.

The joint

Steel on one sideSteel on the other sideThickest plate in the joint (mm, optional)Carbon equivalent Ceq (%, optional)IIW formula: C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15.

Structural discontinuity, high stress area, complex loading or harsh conditionsImportant structural memberWelding site temperature below 0 °CVery rigid structure, thick plate or short weld lengths

Result

Consumable grades for the general case

The strengths differ, so the consumable generally suits the lower strength steel, A (5.1.4.2).

1
2
3
1Y
2Y
3Y
4Y
2Y40①
3Y40①
4Y40①
5Y40①

Lowest suitable grade: 1

Low hydrogen consumables

Generally required (CCS 5.1.4.3).

A higher strength steel is in the joint.

Preheat and heat input

None of the rule's preheat conditions was ticked.
Higher strength steel: consider preheat and control the heat input and the interpass temperature (5.2.3.1).

The rule gives no temperatures. Use your approved welding procedure.

Tack welds

Minimum tack weld length 50 mm (5.1.6.2).

Table 5.1.4.1 as published

Consumable grade	A	B	D	E	AH32 / AH36	DH32 / DH36	EH32 / EH36	FH32 / FH36	AH40	DH40	EH40	FH40
1	×
2	×	×	×
3	×	×	×	×
1Y	×				②
2Y	×	×	×		×	×
3Y	×	×	×	×	×	×	×
4Y	×	×	×	×	×	×	×	×
2Y40	①	①	①		×	×			×	×
3Y40	①	①	①	①	×	×	×		×	×	×
4Y40	①	①	①	①	×	×	×	×	×	×	×	×
5Y40	①	①	①	①	×	×	×	×	×	×	×	×

× means suitable. ① is not advised in normal strength steel. ② applies only to plate 25 mm thick or less.

What this tool covers

CCS Rules for Materials and Welding 2021, Part 3 Chapter 5: Table 5.1.4.1 for hull steels A, B, D, E, AH, DH, EH, FH at 32 and 36, and AH, DH, EH, FH at 40; clause 5.1.4.2 for joints between different steels; 5.1.4.3 for low hydrogen; 5.1.5.4 and 5.2.3.1 for preheat and heat input; 5.1.6.2 for tack welds.

What it does not cover

Preheat temperatures, heat input limits and welding procedure parameters: the rules give none, and they come from your approved welding procedure. It also does not name consumable brands, and it does not replace the approval of the consumables or of the procedure. Other societies' selection tables can differ.

Questions about the selection

Why does a joint between two different steels get the lower steel's consumable?: CCS 5.1.4.2 says that when the steels differ in strength the consumable generally suits the lower strength steel, and that where the strength is the same but the toughness differs it generally suits the lower toughness steel. At structural discontinuities, in high stress areas, with complex loading or in harsh conditions a higher level may be chosen, which the tool shows when you tick the box.
When is a low hydrogen consumable needed?: CCS 5.1.4.3 asks for low hydrogen consumables generally when higher strength steel, or steel with a carbon equivalent above 0.41 %, is welded to steel of the same or lower strength, and for important structural members. Any joint with a higher strength steel falls in the first case.
Does the tool give preheat temperatures?: No. The rule lists when preheat and slow cooling should be considered and gives no temperatures. Above 0.45 % carbon equivalent it also asks you to consider post-weld heat treatment. The temperatures come from your approved welding procedure.

Source

Every cell of Table 5.1.4.1 and the clauses above were read from the page images of the CCS Rules for Materials and Welding 2021. This is the CCS rule, not an IACS unified requirement, so check your society's own table.

This is a selection aid, not an approval. The welding procedure approved by your classification society governs. For plate ready to ship, contact us. Request a quote