山特维克试井钢丝技术说明

Sanicro ™ 36Mo for slicklines

Phil Etheridge 19 Dec. 2011

Content

Introduction Chemical composition Mechanical properties Physical properties Corrosion properties Dimensional range Sheaves and pulleys Testing

Attachments

A .1. Corrosion testing procedures and results

Executive summary

Sanicro 36Mo is a unique alloy, invented by Sandvik specifically for slickline and logging cable armor wire use and is unmatched by any other existing steel alloy. With its extremely high tensile strength and excellent corrosion resistance, Sanicro 36Mo has been used to great advantage in some of the world’s most aggressive environments.

Sanicro 36Mo | UNS N08936

SLICKLINES IN SANICRO™ 36MO

Sanicro 36Mo is a nitrogen-enhanced, high-alloy austenitic stainless steel for service in extreme conditions in the oil and gas industry. The grade is characterized by: • Very high corrosion resistance in both H 2S and chloride environments.

• Extreme resistance in sour conditions, also in the super high strength condition.

• Super high tensile strength and breaking loads, with no additional processing necessary. • Excellent ductility.

•

Very good fatigue properties.

DESIGNATION BY STANDARD • UNS N08936 PRODUCT STANDARD • ASTM B649

The function of alloying elements

Sanicro 36Mo has been designed specifically for the oil and gas industry with the intention

of providing both very high strength and extremely good corrosion resistance in sour well conditions. The various alloying elements have the following functions:

Iron (~28%) Iron (Fe) is the basic building material for all steels. Chromium Chromium (Cr) and Iron (Fe) and together form the basis for stainless steel, (27%) though both the corrosion resistance and formability of simple chromium steels is low. In chromium concentrations above about 11 %, a chrome-oxide passive layer forms on the metal surface. Increasing the chromium content leads to a stronger passivity and thus a higher corrosion resistance. Nickel Nickel (Ni) is added as a powerful austenite stabilizer, to alter the (34%) microstructure from ferritic to austenitic. Austenitic stainless steels have good formability and greater toughness than chromium steels and in addition maintain a better weldability when the alloying content of chromium and molybdenum is high, than is the case with ferritic steels. High nickel content both improves the mechanical properties and stabilizes oxidation properties at high temperatures. Additionally, nickel has a positive effect on general corrosion resistance. Austenitic steels with lower Nickel content have a reduced tensile strength at high temperatures. Molybdenum Molybdenum (Mo) has an effect similar to chromium on the (5.4%) microstructure and significantly increases corrosion resistance. It also contributes to higher strength.Nitrogen Nitrogen (N) is used to increase strength, corrosion resistance and (0.4%) structural stability.(5%) increases the solubility of nitrogen, thus permitting higher nitrogen content and preventing the formation of nitrogen nitrides. In this respect Mn contributes greatly to the strength of the material and also has a positive effect on durability. The high nickel, molybdenum and nitrogen content of Sanicro 36Mo all contribute to the very high strength of the material even in the annealed condition. The strength of

stainless grades with lower nickel and nitrogen contents can be increased by cold-working, but the resulting greatly increased strength leads to reduced ductility and can also cause embrittlement when coupled with the ageing effect of higher temperatures. Cold working can also impair corrosion resistance, especially to stress corrosion cracking.

Sandvik is an integrated manufacturer, meaning we manufacture our steels in our own melting shop in Sandviken, Sweden. Our Argon/Oxygen Decarburization (AOD) process ensures a very low content of those elements which can have a negative effect on corrosion resistance, in particular carbon. Once the composition of any grade of steel has been established, it is repeated with accuracy over and over again, as a glance at the chemical composition of various melts in our mill certificates will confirm.

Chemical composition (nominal) weight % Grade C

Cr

N i

Mo

Mn

N

Fe

Sanicro ™ 36Mo

< 0.020 27 34 5.4 5.0 0.4 Balance