Heat treatment process for improving obdurability of near beta type or metastable beta type titanium alloy

Abstract

The invention relates to a heat treatment process for improving obdurability of a near beta type or metastable beta type titanium alloy. The process comprises the following steps of: firstly, preserving heat at the temperature of T which is more than or equal to T beta-50 DEG C and less than or equal to T beta-10 DEG C, wherein the heat preservation time T (min) is eta * delta max, the delta max is the maximum section thickness of a forge piece, the unit is mm, the eta is a heating coefficient, and the value of the heating coefficient eta is 0.5 to 1.5min / mm; secondly, discharging the forge piece out of a furnace and cooling the forge piece to room temperature by air or water; thirdly, preserving heat of the cooled forge piece at the temperature of T which is more than or equal to 520 DEGC and less than or equal to 560 DEG C, wherein the heat preservation time T is more than or equal to 20min and less than or equal to 1.5h; fourthly, discharging the forge piece out of the furnace andcooling the forge piece to room temperature by air; fifthly, slowly heating the cooled forge piece to the temperature of T which is more than or equal to 480 DEG C and less than or equal to 540 DEG Calong with the furnace, wherein the heating rate is controlled to be within 5 DEG C / min, and the heat preservation time T is more than or equal to 6h and less than or equal to 12h; and finally, cooling the forge piece along with the furnace or discharging the forge piece out of the furnace and cooling the forge piece to room temperature by air. The process is suitable for heat treatment of the near beta type or metastable beta type titanium alloy with ultrahigh obdurability so as to obtain a tissue with high comprehensive performance and multi-scale precipitated phases, which has the requiredultrahigh strength (Rm is more than or equal to 1,500 MPa), high plasticity (A is more than or equal to 5 percent) and high obdurability (KIC is more than or equal to 45 MPa.m < 1 / 2 >), and meet important bearing structural members with ultrahigh obdurability matching required by airplanes.

Description

technical field [0001] The invention relates to a heat treatment process for improving the strength and toughness of near-beta or metastable beta-type titanium alloys, and belongs to the technical field of material heat treatment. Background technique [0002] In the past, under the guidance of strength design and stiffness design ideas, titanium alloys have experienced the development process from low-strength, medium-strength to high-strength and ultra-high-strength. In this development process, although the strengthening and toughening heat treatment process of titanium alloy has been the direction of people's efforts, it is difficult for conventional heat treatment to solve the optimal matching problem between high strength-high plasticity-high fracture toughness and so on. The general situation is that when high strength is obtained (for example, using a low-temperature aging process below 500°C), it is difficult to obtain forgings with high plasticity and high fracture...

AI Technical Summary

Problems solved by technology

In this development process, although the strengthening and toughening heat treatment process of titanium alloy has been the direction of people's efforts, it is difficult to solve the optimal matching problem between high strength-high plasticity-high fracture toughness and so on by conventional heat treatment.

Generally speaking, when high strength is obtained (for example, using a low temperature aging process below 500°C), it is difficult to obtain forgings with high plasticity and high fracture toughness at the same time.

Under the conditions of traditional design ideas and conventional technology, the best match of high strength / ultra-high strength-high plasticity-high toughness of titanium alloy is difficult to break through in practical applications.

Images