Cooling Water System: How WaterCircuit Conditions Influence Copper Mould Tube Service Life and Strand Quality

Many casting defects and premature mould tube failure stem not from the copper tube itself, but from unreasonable coolingwater conditions. This article discusses water velocity, water quality and scaling issues, and explains how proper cooling protects mould tubes and stabilizes continuouscasting output.

Copper mould tubes rely entirely on circulating cooling water to carry away massive heat released by molten steel solidification. While most metallurgical buyers focus heavily on alloy substrate, machining accuracy and surface treatment of mould tubes, the cooling water circuit is often underestimated. In actual production, improper cooling parameters, poor water quality and internal scaling frequently cause premature mould tube damage and recurring strand defects, even when highgrade copper mould tubes are installed.

Water flow velocity inside the cooling channel is one of the most critical parameters. If flow speed is too low, local hotspots will form on the copper wall. Persistent overheating leads to thermal softening, local deformation and thermal fatigue cracks on inner surface. On the contrary, excessively high water velocity may bring strong waterside erosion and cavitation damage on the outer surface of copper tube. Cavitation erosion generates small pits on watercontact surface, which gradually expand and weaken heat exchange efficiency. Balanced water velocity range must be matched according to mould dimension, casting speed and heat load.

Water quality control brings another set of practical challenges for steel plants. Hard water containing calcium and magnesium ions will form mineral scale on coolingchannel inner walls after longtime operation. Even thin scale layers greatly reduce heat transfer capacity. Heat cannot be removed in time, resulting in uneven temperature distribution across mould wall. Under such circumstance, the mould tube suffers intensified thermal stress, accelerating fatigue damage. Meanwhile, uneven cooling creates unstable airgap between copper wall and solidifying shell, triggering longitudinal cracks, depressions and other strand surface defects.

Apart from scaling, suspended particles and corrosive ions in circulating water will cause pitting corrosion on the outer copper surface. Tiny corrosion points develop into hidden danger areas, which may further expand under repeated thermal cycles. Many unexpected mould tube failures can be traced back to longterm untreated circulating water rather than material defects.

It is worth noting that cooling condition interacts closely with mould tube performance. A highquality copper mould tube cannot deliver its designed service life if operating under poor cooling conditions. Steel mills should monitor key indicators including water flow rate, water pressure difference, water hardness and pH value regularly, and implement periodic cleaning for cooling channels.

As a professional supplier of continuous casting copper mould tubes, JISteel provides technical reference for coolingwater parameters together with delivered products. Based on billet size, casting speed and heatload level, our team offers recommended range of water flow and pressure for reference. We remind customers that reasonable watercircuit maintenance helps give full play to mould tube performance and extend service cycle.

Against the background of pursuing highefficiency continuous casting, the cooling water system deserves equal attention as mould tube hardware itself. Optimized cooling parameters and qualified circulating water not only reduce unexpected mould replacement cost, but also improve strand surface quality and overall production stability for metallurgical enterprises worldwide.