A kind of high-strength austenitic stainless steel for automobile frame and its manufacturing method

Abstract

The invention relates to a high-strength austenitic stainless steel for automobile frames and a manufacturing method thereof. The austenitic stainless steel comprises the following chemical components in percentage by weight: 0.05-0.15% of C, 0.4-1% of Si, 7-10% of Mn, at most 0.03% of P, at most 0.01% of S, 13-15% of Cr, 1-2% of Ni, 0.1-0.2% of N, 0.05-0.2% of Nb, at most 0.1% of Ti, 0.05-0.1% of Ce, and the balance of Fe and inevitable impurities, wherein 0.1%<=Nb+Ti<=0.25%.In order to ensure the comprehensive mechanical properties to satisfy the requirements, the austenitic stainless steel manufacturing method adopts two different production techniques for producing high-strength stainless steel with different thicknesses. The yield strength of the finished austenitic stainless steel can reach 600 MPa above, the tensile strength is up to 1000 MPa above, and the elongation percentage is up to 28% above. The austenitic stainless steel is suitable for manufacturing automobile frames, anti-collision beams and other high-strength parts as well as other new-energy vehicle structural members.

Description

technical field [0001] The invention relates to stainless steel and a manufacturing method thereof, in particular to a high-strength austenitic stainless steel for automobile frames and a manufacturing method thereof. The obtained austenitic stainless steel has high strength, good welding performance and good low-temperature toughness, and is suitable for manufacturing Frames, high-strength components such as anti-collision beams and other structural parts of new energy vehicles. Background technique [0002] With the increasingly stringent requirements for environmental protection and resource conservation at home and abroad, the concept of "full life cycle cost" has gradually penetrated into the automotive industry. The lightweight and longer service life of automotive products have become the inevitable development of automotive steel materials in the future. trend. [0003] In order to reduce the weight of the car body as much as possible without affecting the safety of...

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Problems solved by technology

[0009] In Table 1, Japanese patents JP54,038,217, JP52,024,914, JP2001131713 and Chinese patent CN201110027216.3 disclose the chemical composition of metastable austenitic stainless steel. These chemical compositions all contain Cu element, and Cu is difficult to recover in stainless steel. Disadvantages of reuse

[0010] The metastable austenitic stainless steels disclosed in Chinese patents CN200810035045.7, CN200710039748.2 and CN200710038386.5 have a Cr content greater than 15%, resulting in higher alloy costs

Among them, the patent CN200710039748.2 does not contain Ni elements, and completely relies on Mn and N elements to adjust the structure, which is difficult to produce, and it can be seen from its examples that the deformation-induced martensitic transformation tendency of this designed stainless steel is very serious, and the work hardening The process has a large loss of elongation

[0011] The high-strength stainless steel patent disclosed in Chinese patent CN200810042817.X aims to provide a high-strength non-magnetic stainless steel. In order to achieve the non-magnetic effect, its Mn content, Cr content and N content are all high, especially the N content is very high. As a result, production is difficult, and Nb, Ti, V, and Mo are added at the same time. In addition to high cost, its yield strength is above 380Mpa, which cannot meet the performance requirements of frame and body structural parts.

[0012] AISI201 and AISI301 are currently more common high-strength stainless steel sheets, but their original design intention is not to apply to new energy bus frames, so their alloy costs are relatively high. For example, the Cr content of AISI201 is 16%-18%, and the precious metal Ni content is 3.5%. -5.5%, the Ni content of AISI301 alone reaches 6%-8%, so the material cost of using it to make the bus frame is quite high, and the increase of its material cost makes the replacement of stainless steel material less effective in reducing the cost of the whole life cycle obvious

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