ASTM A333 Low Temperature Seamless Steel Pipe

ASTM A333 Low Temperature Seamless Steel Pipe

 Low Temperature Seamless Steel Pipe in petrochemical industry is mainly used in the production of ethylene, polypropylene, synthetic ammonia, LPG, etc., as well as the manufacturing industry of deep-cooling equipments, ultra-low-temperature cold storage, and pipelines for transporting ultra-low-temperature liquefied gases.This paper mainly introduces ASTM A 333/A 333MThis paper mainly introduces A333GR.6 in ASTM A 333/A 333M.
A333GR.6 Chemical Composition
From the American Standard ASTM A 333/A 333M prior to 2013 only the chemical elements C, Mn, S, and P were required as listed below:

From 2016 onwards, the ASTM A 333/A 333M standard has made great adjustments to the chemical composition of GR.6 low-temperature steel, and on the basis of retaining the conventional five elements and their contents unchanged, elements such as Cr, Ni, Mo, Cu, V, and Nb have been added, and the new elements are given as the upper limit of the content, that is to say, we used to always think that the C-Mn low-temperature steel A333GR.6 ASTM A 333/A 333M-2016 version of A333GR.6 alloy elements are listed below:

A333GR.6 Chemical element analysis
(1) C element
C element can be solid solution in steel to form interstitial solid solution, the diffusion of carbon atoms in the heat treatment process or bias on the formation and distribution of carbide and steel properties have an important impact. Carbide is a hard phase, can improve the strength, hardness and wear resistance of steel, but not conducive to the improvement of steel toughness, need to minimize the carbon content;
(2) Si, Mn elements
Si is the steel smelting process in order to remove the oxygen in the steel, Si helps to enhance the high-temperature steel deoxidation and acid corrosion resistance; Mn is a reinforcing element that can improve the hardness of steel, wear-resistant properties and reversal of austenite stabilization, but Mn is easy to form a mixture of MnS with the S of the performance of the steel to bring about a bad influence;
(3) S, P elements
From the role of elements on the low-temperature toughness, generally believe that C, Si, P, S, N, etc. are harmful elements, and P is the most harmful, and Mn, Ni, etc. are beneficial elements. Therefore, ASTM A 333/A333M-2013 mainly relies on Mn to improve the low-temperature performance of Gr6, and strictly control the S, P content.
(4) Ni element
Ni is an alloying element that promotes the stable existence of austenite, which is conducive to the improvement of steel plasticity and strength, and at the same time reduces the brittle-hard transition temperature of steel, and the nickel-rich reversed austenite can be preserved and stabilized at very low temperatures, which has an important impact on the improvement of the low-temperature toughness of A333Gr6. 2016 version of the later version of the A333GR.6 further enhanced its low-temperature properties with the help of the new addition of Ni as well as the alloying effect of V, Nb and so on. low-temperature properties.