Internal high-pressure deforming method for manufacturing steel pipe, involves deforming workpiece in traction by compressing gas, and hardening workpiece by temperature of gas from inner side and temperature of die from outer side, in die

摘要

The method involves pre-heating a tubular workpiece (2) formed from a steel material within or at outer side of a closed forming die (1), where ends (3) of the workpiece in a form hollow space (4) of the forming die are sealed. A gas e.g. nitrogen, under pressure is fed into an inner space (6) of the workpiece. The workpiece is inserted into the forming die, and the workpiece is deformed in a traction by compressing the gas. The workpiece is hardened by temperature of the gas from inner side and temperature of the die from outer side, in the die.