According to GB/T9711.1 pipeline steel pipe performance requirements, according to the different tempering temperature, can be divided into the following kinds of tempering:
[1] Low temperature tempering (150-250 degrees)
The microstructure obtained by low temperature tempering is tempered martensite. Its purpose is to reduce the quenching stress and brittleness of hardened steel on the premise of maintaining its high hardness and high wear resistance, so as to avoid cracking or premature damage during use. It is mainly used for all kinds of high carbon cutting tools, measuring tools, GB/T9711.1 pipeline steel pipe, rolling bearings and carburizing parts, etc., the hardness after tempering is GENERALLY HRC58-64.
[2] Moderate temperature tempering (250-500 degrees)
The microstructure obtained by moderate tempering is tempered trostite. The purpose is to obtain high yield strength, elastic limit and high toughness. Therefore, it is mainly used for all kinds of GB/T9711.1 pipeline steel pipe and hot mold treatment, after tempering hardness is generally HRC35-50.
[3] High temperature tempering (500-650 degrees)
The microstructure obtained by high temperature tempering is tempered sortensite. Commonly, the heat treatment combined with quenching and tempering is called quenching and tempering. Its purpose is to obtain better comprehensive mechanical properties of strength, hardness, plasticity and toughness. Therefore, it is widely used in automobiles, GB/T9711.1 pipeline steel pipe, machine tools and other important structural parts, such as connecting rod, bolt, gear and shaft. The hardness after tempering is generally HB200-330.
Standard
API SPEC 5L -- American Petroleum Institute Standard
GB/T9711 -- National standard of China
Uses
Used for oxygen, water and oil conveying pipe in petroleum and natural gas industry
Main production of steel pipe grades:
B, X42, X52, X60, X65, X70 L245 L290 L320 L360 L390 L450 L485
Mechanical properties
| Standard | Product Level | Steel Grade | Yield Strength (min), Mpa | Tensile Strength（MPa） |
| API 5L GB/T9711.2 | PSL 1 | A or L210 | 210 | 335 |
| B or L245 | 245 | 415 | ||
| x42 or L290 | 290 | 415 | ||
| X46 or L320 | 320 | 435 | ||
| X52 or L360 | 360 | 460 | ||
| X56 or L390 | 390 | 490 | ||
| X60 or L415 | 415 | 520 | ||
| X70 | 483 | 565 | ||
| PSL 2 | BR or L245R | 245~450 | 415~760 | |
| X42R or L290R | 290~495 | 415~760 | ||
| BN or L245N | 245~450 | 415~760 | ||
| X42N or L290N | 290~495 | 415~760 | ||
| X46N or L320N | 320~525 | 435~760 | ||
| X52N or L360N | 360~530 | 460~760 | ||
| X56N or L390N | 390~545 | 490~760 | ||
| X60N or L415N | 415~565 | 520~760 | ||
| X65N or L450N | 425~566 | 525~760 | ||
| X70 or L480 | 484~565 | 565~768 | ||
| X80 | 552~690 | 621~827 |
Table of chemical Elements in pipeline
| Product Level | Steel Grade | Chemical Composition, % | ||||||||
| C | Mn | P | S | And | IN | Nb | Of | CEpcm | ||
| PSL 1 | B or L245 | ≤0.28 | ≤1.20 | ≤0.030 | ≤0.030 | - | - | - | - | - |
| x42 or L290 | ≤0.28 | ≤1.30 | ≤0.030 | ≤0.030 | - | - | - | - | - | |
| X46 or L320 | ≤0.28 | ≤1.40 | ≤0.030 | ≤0.030 | - | - | - | - | - | |
| X52 or L360 | ≤0.28 | ≤1.40 | ≤0.030 | ≤0.030 | - | - | - | - | - | |
| X56 or L390 | ≤0.28 | ≤1.40 | ≤0.030 | ≤0.030 | - | - | - | - | - | |
| X60 or L415 | ≤0.28 | ≤1.40 | ≤0.030 | ≤0.030 | - | - | - | - | - | |
| X70 | ≤0.28 | ≤1.40 | ≤0.030 | ≤0.030 | - | - | - | - | - | |
| PSL 2 | BR or L245R | ≤0.24 | ≤1.20 | ≤0.025 | ≤0.015 | ≤0.40 | c | c | ≤0.04 | ≤0.25 |
| X42R or L290R | ≤0.24 | ≤1.20 | ≤0.025 | ≤0.015 | ≤0.40 | ≤0.06 | ≤0.05 | ≤0.04 | ≤0.25 | |
| BN or L245N | ≤0.24 | ≤1.20 | ≤0.025 | ≤0.015 | ≤0.40 | c | c | ≤0.04 | ≤0.25 | |
| X42N or L290N | ≤0.24 | ≤1.30 | ≤0.025 | ≤0.015 | ≤0.40 | ≤0.06 | ≤0.05 | ≤0.04 | ≤0.25 | |
| X46N or L320N | ≤0.24 | ≤1.40 | ≤0.025 | ≤0.015 | ≤0.40 | ≤0.07 | ≤0.05 | ≤0.04 | ≤0.25 | |
| X52N or L360N | ≤0.24 | ≤1.40 | ≤0.025 | ≤0.015 | ≤0.45 | ≤0.10 | ≤0.05 | ≤0.04 | ≤0.25 | |
| X56N or L390N | ≤0.24 | ≤1.40 | ≤0.025 | ≤0.015 | ≤0.45 | ≤0.10 | ≤0.05 | ≤0.04 | ≤0.25 | |
| X60N or L415N | ≤0.24 | ≤1.40 | ≤0.025 | ≤0.015 | ≤0.45 | ≤0.10 | ≤0.05 | ≤0.04 | - | |
| X65N or L450N | ≤0.24 | ≤1.40 | ≤0.025 | ≤0.015 | ≤0.45 | ≤0.10 | ≤0.05 | ≤0.04 | - | |
| X70N | ≤0.24 | ≤1.40 | ≤0.025 | ≤0.015 | ≤0.45 | ≤0.10 | ≤0.05 | ≤0.04 | - | |
| X80 | ≤0.24 | ≤1.40 | ≤0.025 | ≤0.015 | ≤0.45 | ≤0.10 | ≤0.05 | ≤0.04 | ||
Post time: May-23-2022