1.0 INTRODUCTION

JFE has been manufacturing and marketing abrasion-resistant steel plates since 1955. Nowadays, JFE EVER-HARD steel plates have found a place in a broad range of fields, such as civil and architectural engineering, mining, agricultural machinery and other types of industrial machinery.

JFE has been investigating the effect of alloying elements and manufacturing conditions on abrasion-resistance, weldability and formability. This pursuit has led to the development of JFE EHSP super abrasion-resistant steel, a new type based on a technique that improves the abrasion resistance without increasing the hardness. This new approach to the alloy-design of JFE

EHSP has been achieved by a uniform dispersion of a lot of high hardness titanium precipitates in steel.

2.0 JFE EHSP SPECIFICATION

3.1 General Rules for good welds in JFE EHSP steel

• Use controlled hydrogen process.
• Select consumables per Table 6, 7 or 8.
• Consumables must be correctly stored in order to maintain their controlled hydrogen properties. See current editions of Lincoln Customer Application Bulletins 5, 55, 58 and 60 for information on storage and redrying of welding consumables.
• Clean joint area and up to approximately 12 mm on either side to remove oil, grease, paint, rust and scale before welding.
• Remove 1-2 mm from flame cut or gouged surfaces by grinding.
• Ensure that preheat and interpass temperatures, and heat input limitations specified in Tables 4 and 5 are followed closely.
• Position job for downhand welding where possible.
• Always use stringer beads, never wide weave beads.
• Deposit root runs with Jetweld LH-70, Jetweld LH-75 MR or Easyarc 18MR (E4818). These will have the least likelihood of hot tearing in joints in thicker and more highly restrained sections, due to the high ductility of the weld metal.
• Tempering beads with low hydrogen consumables such as Jetweld LH-70, LH-75 MR, or Easyarc 18MR may be deposited as extra weld reinforcement or to refine the final passes of full strength welds and heat affected zones at the top of the joint. These are normally deposited partially over the final full strength runs and partially on the plate surface adjacent to the weld.
• When required, back gouge using the air-arc process and remove scale by grinding. Do not use oxy-acetylene for back gouging.
• Arc strikes outside the weld zone can result in cracks, particularly in dynamically loaded structures. All arc strikes should therefore be made within the joint preparation.
• Grinding toes of fillet welds is particularly important in fatigue applications.
• When preheating, follow the guidelines illustrated in Figure 1.

Welding JFE EHSP to mild steel is straightforward. It is usual to employ similar consumables to those materials recommended for fillet welding (Tables 6 and 7). Higher strength consumables may be used but admixture from the mild steel will lower the deposit strength to something between that of the JFE EHSP being welded and the mild steel, and the mild steel fusion zone will still be the weakest part of the joint. It is most important to observe all the precautions regarding process, arc energy input and preheat of the JFE EHSP.

When welding JFE EHSP to austenitic stainless steel, the "25 Cr-12 Ni" E309 electrode type (and "25 Cr-20 Ni" E310 electrode type for joint configurations involving high levels of admixture of mild steel) are recommended to ensure an austenitic weld metal microstructure. Again any necessary preheat/arc energy input requirements for the JFE EHSP grade must be observed.

E309 and E310 electrodes are also suitable for welding JFE EHSP to austenitic manganese steels, with the correct preheat and arc energy input for both steel types. The manganese steel requires a maximum interpass temperature of 250°C (controlled as per Figure 1.) and fast cooling from welding temperature to avoid cracking of the manganese steel component.