Hardenability situation is the same high-pressure alloy pipe, hardness after quenching can reflect the yield strength and tensile strength, high alloy pipe, so high alloy pipe drawings and technical conditions generally only prescribed hardness values. Only very important parts before the provisions of other mechanical properties.

Quenched and tempered high alloy pipe hardness determination must take into account the requirements of the manufacturing process and the use of load conditions. From the manufacturing process to consider, hope quenched parts in the rough state, then carry out machining and assembly. Such distortion and decarbonization high alloy pipe heat produced when cutting be eliminated after processing. However, using this manufacturing process parts, the hardness is not too high, generally not more than 300HB, the individual does not exceed 350HB, otherwise unfavorable for cutting. Higher hardness required parts (if vehicle axle requires a hardness of 341 ~ 415HB), only the first cutting, then quenching and tempering treatment, then high-pressure alloy pipe should be heated to prevent the removal and deformation, and sometimes heat To add a step after straightening. Small quantities or single-piece production parts, cutting the allowable hardness can be raised.

Determine the hardness of quenched and tempered high alloy pipe must also take into account the characteristics of the production, small batch single products, high alloy pipe can select different different hardnesses, large quantities of water production plant hope hardness range of most high-pressure alloy pipe uniform or fixed within a few hardness range, which the organization has a great convenience heat production.

From the standpoint of the use of high-pressure alloy pipe, determine to be noted that the shape of the high-pressure alloy pipe working conditions and quality of parts when adjusting the hardness of the parts. Generally speaking, high hardness, tensile strength, yield strength and fatigue strength of smooth specimen are high, but lower plasticity index, increased sensitivity and tendency to brittle fracture stress concentration, therefore, from the stress concentration when the high-pressure alloy pipe notch effect (splines, grooves or variation in section), in order to make the stress distribution, reducing stress concentration, then lower hardness but higher fatigue performance can be obtained.