اتصالات بین فولاد زنگ نزن سوپر دو فازی و فولاد HSLA

Effect of heat input on microstructure and mechanical properties of

dissimilar joints between super duplex stainless steel and high strength low alloy steel

اثر حرارت ورودی بر ریزساختار و خواص مکانیکی اتصالات غیر مشابه بین

فولاد زنگ نزن سوپر دو فازی و فولاد کم آلیاژ با استحکام بالا

ABSTRACT

In the present study, microstructure and mechanical properties of UNS S32750 super duplex stainless steel (SDSS)/API X-65 high strength low alloy steel (HSLA) dissimilar joint were investigated. For this purpose, gas tungsten arc welding (GTAW) was used in two different heat inputs: 0.506 and 0.86 kJ/mm. The microstructures investigation with optical microscope, scanning electron microscope and X-ray diffraction showed that an increase in heat input led to a decrease in ferrite percentage, and that detrimental phases were not present. It also indicated that in heat affected zone of HSLA base metal in low heat input, bainite and ferrite phases were created; but in high heat input, perlite and ferrite phases were created. The results of impact tests revealed that the specimen with low heat input exhibited brittle fracture and that with high heat input had a higher strength than the base metals.

 

مشخصه یابی فولاد یاتاقان Characteristics of 100Cr6 bearing steel

Characteristics of 100Cr6 bearing steel after thixoforming process performed 

with prototype device

مشخصه یابی فولاد یاتاقان 100Cr6 بعد از فرایند thixoforming انجام شده با ابزار مدل اولیه

ABSTRACT

A device based on a high pressure die-casting(HPDC) machine was constructed, with a capacity to produce thixo-casts from steel. After inductive heating to the required semi-solid temperature range, the samples were transported in a protective argon atmosphere to a cylinder of modified HPDC and injected into a pre-heated die. Bearing steel 100Cr6 (after forging) was used as the feedstock material. The metallographic analysis of the steel showed a homogenous structure within a whole volume characterized by a grain size between 2 μm and 8 μm. Differential scanning calorimetry (DSC) analysis allowed to estimate the process temperature for thixoforming at 1 390 °C which was attributed to about 45% of a liquid phase.