Who knows how wide the range of the welding heat-affected zone is

The heat-affected zone is the area of the base material where its properties change as a result of being exposed to high temperatures for a short period due to the welding heat flow, followed by rapid cooling. Depending on the maximum temperature reached and the cooling rate, the heat-affected zone can be divided into several zones. For the welded heat-affected zone that is difficult to harden into steel, it can be classified in order from farther away from the fusion zone as: the overheated zone (also known as the coarse-grain zone), the recrystallization zone (also known as the normalizing zone or fine-grain zone), the incompletely crystallized zone (also known as the partially normalized zone or zone of partial phase transformation), and the recrystallized zone. It does indeed have a certain relationship with the plate thickness; the specific details need to be determined through welding procedure qualification.

I’m truly grateful. For example, the pipe diameter is 830 mm, the wall thickness is 9 mm, the material is 16Mn, and it’s welded together. At what distance from the pipe end does the temperature drop to 100°C?

The width of the heat-affected zone is related to the welding method and welding parameters; controlling the size of the heat-affected zone can be achieved by regulating the amount of heat input during welding

The heat-affected zone is also related to the welding current; it is primarily due to the heat generated

The average total width of the heat-affected zone varies depending on the welding method; for manual arc welding, it is 6.0–8.0 mm； Submerged arc automatic welding 2.3-4.0mm ； Electroslag welding 25-35mm ； Oxygen, acetylene gas welding 27.0mm ； Vacuum electron beam welding: 0.05–0.75 mm.

It is generally taken as 1-3 times the wall thickness.

I found some new perspectives from other websites for your reference: Easily quenchable steels include medium-carbon steels (35, 40, 45, 50 steels), low-carbon tempered high-strength steels (WC ≤ 0.25%), medium-carbon tempered high-strength steels (WC 0.25%–0.45%), heat-resistant steels, and low-temperature steels. Their heat-affected zones can attain a martensitic structure even when cooled in air after welding, remaining in a quenched state. If the base metal is in an annealed state prior to welding, the microstructure of the heat-affected zone after welding can be divided into a fully quenched region and a partially quenched region ； If the base metal is in a quenched state before welding, a tempering zone will also be formed. 1. The full quenching zone refers to the area where the heating temperature is above Ac3; in this zone, all of the austenite transforms into martensite. It includes the superheated zone and the recrystallization zone found in the heat-affected zone of steels that are difficult to quench. Due to the presence of a quenched microstructure in this area, its strength and hardness increase while plasticity and impact toughness decrease, and it is prone to the formation of cold cracks. 2. The incomplete quenching zone refers to the range where the heating temperature is between Ac1 and Ac3; after welding, the austenite transforms into martensite, while the original ferrite remains unchanged, only growing to varying degrees, ultimately resulting in a martensite-ferrite microstructure. The microstructure and properties of this section are highly uneven, with a decrease in plasticity and impact toughness. 3. Tempering zone: If the base metal is in a quenched state before welding, a tempering process of varying degrees occurs in the temperature range below Ac1; this area is known as the tempering zone. The hardness in the tempering zone decreases while plasticity increases.

The width of the welding heat-affected zone is related to the welding method and welding parameters used; it can generally be found in relevant welding literature